U.S. patent application number 15/002818 was filed with the patent office on 2016-08-11 for metal powder for powder metallurgy, compound, granulated powder, and sintered body.
The applicant listed for this patent is Seiko Epson Corporation. Invention is credited to Hidefumi NAKAMURA.
Application Number | 20160228948 15/002818 |
Document ID | / |
Family ID | 55353016 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160228948 |
Kind Code |
A1 |
NAKAMURA; Hidefumi |
August 11, 2016 |
METAL POWDER FOR POWDER METALLURGY, COMPOUND, GRANULATED POWDER,
AND SINTERED BODY
Abstract
A metal powder comprising particles, which contain Fe, Cr, Si
and C, and in which when one element selected from the group
consisting of Ti, V, Y, Zr, Nb, Hf, and Ta is defined as a first
element, and one element selected from the group consisting of Ti,
V, Y, Zr, Nb, Hf, and Ta, and having a higher group number in the
periodic table than that of the first element or having the same
group number in the periodic table as that of the first element and
a higher period number in the periodic table than that of the first
element is defined as a second element, the first element is
contained in a proportion of 0.01% by mass or more and 0.5% by mass
or less, and the second element is contained in a proportion of
0.01% by mass or more and 0.5% by mass or less.
Inventors: |
NAKAMURA; Hidefumi;
(Hachinohe, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seiko Epson Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
55353016 |
Appl. No.: |
15/002818 |
Filed: |
January 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2301/35 20130101;
C22C 38/48 20130101; B22F 2998/10 20130101; C22C 38/50 20130101;
B22F 5/00 20130101; C22C 38/46 20130101; B22F 1/0003 20130101; C22C
38/005 20130101; B22F 3/15 20130101; B22F 3/15 20130101; C22C 38/04
20130101; B22F 1/0059 20130101; B22F 3/10 20130101; B22F 3/1021
20130101; B22F 2302/45 20130101; C22C 33/0285 20130101; B22F 1/0059
20130101; C22C 38/44 20130101; C22C 38/002 20130101; B22F 2998/10
20130101; C22C 38/02 20130101; B22F 3/02 20130101 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B22F 5/00 20060101 B22F005/00; C22C 38/00 20060101
C22C038/00; C22C 38/48 20060101 C22C038/48; C22C 38/46 20060101
C22C038/46; C22C 38/44 20060101 C22C038/44; B22F 3/15 20060101
B22F003/15; C22C 38/50 20060101 C22C038/50 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 9, 2015 |
JP |
2015-023385 |
Claims
1. A metal powder for powder metallurgy, comprising particles,
which contain Fe as a principal component, Cr in a proportion of
0.2% by mass or more and 35% by mass or less, Si in a proportion of
0.2% by mass or more and 3% by mass or less, and C in a proportion
of 0.005% by mass or more and 2% by mass or less, and in which when
one element selected from the group consisting of Ti, V, Y, Zr, Nb,
Hf, and Ta is defined as a first element, and one element selected
from the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta, and
having a higher group number in the periodic table than that of the
first element or having the same group number in the periodic table
as that of the first element and a higher period number in the
periodic table than that of the first element is defined as a
second element, the first element is contained in a proportion of
0.01% by mass or more and 0.5% by mass or less, and the second
element is contained in a proportion of 0.01% by mass or more and
0.5% by mass or less, wherein the content of Cr on the surface of
each particle is 0.2% by atom or more and 15% by atom or less and
is 70% or more and 170% or less the content of Cr at a depth of 60
nm from the surface of the particle.
2. The metal powder for powder metallurgy according to claim 1,
wherein the content of Si on the surface of each particle is 155%
or more and 800% or less the content of Si at a depth of 60 nm from
the surface of the particle.
3. The metal powder for powder metallurgy according to claim 1,
wherein the ratio of the content of O to the content of Si on the
surface of each particle is 0.05 or more and 0.4 or less.
4. The metal powder for powder metallurgy according to claim 1,
wherein the content of Cr on the surface of each particle is lower
than the content of Cr in the whole particle.
5. The metal powder for powder metallurgy according to claim 1,
wherein the ratio (X1/X2) of a value (X1) obtained by dividing the
content (E1) of the first element by the mass number of the first
element to a value (X2) obtained by dividing the content (E2) of
the second element by the mass number of the second element is 0.3
or more and 3 or less.
6. The metal powder for powder metallurgy according to claim 1,
wherein the sum of the content of the first element and the content
of the second element is 0.05% by mass or more and 0.8% by mass or
less.
7. The metal powder for powder metallurgy according to claim 1,
wherein the metal powder has an average particle diameter of 0.5
.mu.m or more and 30 .mu.m or less.
8. A compound, comprising the metal powder for powder metallurgy
according to claim 1 and a binder which binds the particles of the
metal powder for powder metallurgy to one another.
9. A compound, comprising the metal powder for powder metallurgy
according to claim 2 and a binder which binds the particles of the
metal powder for powder metallurgy to one another.
10. A compound, comprising the metal powder for powder metallurgy
according to claim 3 and a binder which binds the particles of the
metal powder for powder metallurgy to one another.
11. A compound, comprising the metal powder for powder metallurgy
according to claim 4 and a binder which binds the particles of the
metal powder for powder metallurgy to one another.
12. A granulated powder, wherein the granulated powder is obtained
by granulating the metal powder for powder metallurgy according to
claim 1.
13. A granulated powder, wherein the granulated powder is obtained
by granulating the metal powder for powder metallurgy according to
claim 2.
14. A granulated powder, wherein the granulated powder is obtained
by granulating the metal powder for powder metallurgy according to
claim 3.
15. A granulated powder, wherein the granulated powder is obtained
by granulating the metal powder for powder metallurgy according to
claim 4.
16. A sintered body, wherein the sintered body is produced by
sintering the metal powder for powder metallurgy according to claim
1.
17. A sintered body, wherein the sintered body is produced by
sintering the metal powder for powder metallurgy according to claim
2.
18. A sintered body, wherein the sintered body is produced by
sintering the metal powder for powder metallurgy according to claim
3.
19. A sintered body, wherein the sintered body is produced by
sintering the metal powder for powder metallurgy according to claim
4.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Japanese Patent
Application No. 2015-023385 filed on Feb. 9, 2015. The entire
disclosures of Japanese Patent Application No. 2015-023385 is
hereby incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a metal powder for powder
metallurgy, a compound, a granulated powder, and a sintered
body.
[0004] 2. Related Art
[0005] In a powder metallurgy method, a composition containing a
metal powder and a binder is molded into a desired shape to obtain
a molded body, and the obtained molded body is degreased and
sintered, whereby a sintered body is produced. In such a process
for producing a sintered body, an atomic diffusion phenomenon
occurs among particles of the metal powder, whereby the molded body
is gradually densified, resulting in sintering.
[0006] For example, JP-A-2012-87416 proposes a metal powder for
powder metallurgy which contains Zr and Si, with the remainder
including at least one element selected from the group consisting
of Fe, Co, and Ni, and inevitable elements. According to such a
metal powder for powder metallurgy, the sinterability is enhanced
by the action of Zr, and a sintered body having a high density can
be easily produced.
[0007] The thus obtained sintered body has recently become widely
used for a variety of machine parts, structural parts, and the
like.
[0008] However, depending on the use of a sintered body, further
densification is needed in some cases. In such a case, a sintered
body is further subjected to an additional treatment such as a hot
isostatic pressing treatment (HIP treatment) to increase the
density, however, the workload is significantly increased, and also
an increase in the cost is inevitable.
[0009] Therefore, an expectation for realization of a metal powder
capable of producing a sintered body having a high density without
performing an additional treatment or the like has increased.
SUMMARY
[0010] An advantage of some aspects of the invention is to provide
a metal powder for powder metallurgy, a compound, and a granulated
powder, each of which is capable of producing a sintered body
having a high density, and a sintered body having a high
density.
[0011] The advantage can be achieved by aspects of the invention
described below.
[0012] A metal powder for powder metallurgy according to an aspect
of the invention includes particles, which contain Fe as a
principal component, Cr in a proportion of 0.2% by mass or more and
35% by mass or less, Si in a proportion of 0.2% by mass or more and
3% by mass or less, and C in a proportion of 0.005% by mass or more
and 2% by mass or less, and in which when one element selected from
the group consisting of Ti, V, Y, Zr, Nb, Hf, and Ta is defined as
a first element, and one element selected from the group consisting
of Ti, V, Y, Zr, Nb, Hf, and Ta, and having a higher group number
in the periodic table than that of the first element or having the
same group number in the periodic table as that of the first
element and a higher period number in the periodic table than that
of the first element is defined as a second element, the first
element is contained in a proportion of 0.01% by mass or more and
0.5% by mass or less and the second element is contained in a
proportion of 0.01% by mass or more and 0.5% by mass or less,
wherein the content of Cr on the surface of each particle is 0.2 at
% or more and 15 at % or less and is 70% or more and 170% or less
the content of Cr at a depth of 60 nm from the surface of the
particle.
[0013] According to this, the particles of the metal powder for
powder metallurgy each have a passivation film derived from a Cr
oxide whose thickness is small to some extent, and therefore, the
decrease in the sinterability of the particles due to the
passivation film can be suppressed. As a result, the densification
during sintering of the particles is achieved, and thus, a sintered
body having a high density can be produced without performing an
additional treatment.
[0014] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the content of Si on
the surface of each particle is 155% or more and 800% or less the
content of Si at a depth of 60 nm from the surface of the
particle.
[0015] According to this, Si is segregated on the surface of each
particle, and this Si functions as a deoxidizing element which
suppresses the oxidation of Fe or Cr, and therefore, when the
particles are sintered, the generation of a large amount of iron
oxide or chromium oxide can be suppressed. As a result, the
particles have more excellent sinterability and a sintered body
having a higher density can be produced.
[0016] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the ratio of the
content of 0 to the content of Si on the surface of each particle
is 0.05 or more and 0.4 or less.
[0017] According to this, even if Si is segregated on the surface
of each particle, the ratio of Si present in the form of silicon
oxide can be sufficiently decreased. As a result, the deoxidizing
effect of Si can be more reliably exhibited while suppressing the
decrease in sinterability due to the presence of a large amount of
silicon oxide.
[0018] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the content of Cr on
the surface of each particle is lower than the content of Cr in the
whole particle.
[0019] According to this, the excessive increase in the thickness
of the passivation film formed on the surface of each particle can
be suppressed, and therefore, the sinterability of the particle can
be particularly enhanced.
[0020] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the ratio (X1/X2) of
a value (X1) obtained by dividing the content (E1) of the first
element by the mass number of the first element to a value (X2)
obtained by dividing the content (E2) of the second element by the
mass number of the second element is 0.3 or more and 3 or less.
[0021] According to this, the balance between the deposition amount
of a carbide or the like of the first element and the deposition
amount of a carbide or the like of the second element can be
optimized. As a result, pores remaining in a molded body can be
eliminated as if they were swept out sequentially from the inside,
and therefore, pores generated in the sintered body can be
minimized. Accordingly, a metal powder for powder metallurgy
capable of producing a sintered body having a high density and
excellent sintered body properties is obtained.
[0022] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the sum of the
content of the first element and the content of the second element
is 0.05% by mass or more and 0.8% by mass or less.
[0023] According to this, the densification of a sintered body to
be produced becomes necessary and sufficient.
[0024] In the metal powder for powder metallurgy according to the
aspect of the invention, it is preferred that the metal powder has
an average particle diameter of 0.5 .mu.m or more and 30 .mu.m or
less.
[0025] According to this, pores remaining in a sintered body are
extremely decreased, and therefore, a sintered body having a
particularly high density and particularly excellent mechanical
properties can be produced.
[0026] A compound according to an aspect of the invention includes
the metal powder for powder metallurgy according to the aspect of
the invention and a binder which binds the particles of the metal
powder for powder metallurgy to one another.
[0027] According to this, a compound capable of producing a
sintered body having a high density is obtained.
[0028] A granulated powder according to an aspect of the invention
is obtained by granulating the metal powder for powder metallurgy
according to the aspect of the invention.
[0029] According to this, a granulated powder capable of producing
a sintered body having a high density is obtained.
[0030] A sintered body according to an aspect of the invention is
produced by sintering the metal powder for powder metallurgy
according to the aspect of the invention.
[0031] According to this, a sintered body having a high density is
obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0033] FIG. 1 is a view schematically showing the cross sections of
particles contained in an embodiment of a metal powder for powder
metallurgy according to the invention.
[0034] FIG. 2 is an enlarged view of an area A of the cross section
of the particle shown in FIG. 1 and is a view for illustrating a
manner of performing an analysis in the depth direction by Auger
electron spectroscopy in combination with sputtering of the surface
of the particle.
[0035] FIG. 3 shows the Auger electron spectra obtained from a
particle of a metal powder for powder metallurgy of sample No.
1.
[0036] FIG. 4 shows the Auger electron spectra obtained from a
particle of a metal powder for powder metallurgy of sample No.
23.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0037] Hereinafter, a metal powder for powder metallurgy, a
compound, a granulated powder, and a sintered body according to the
invention will be described in detail with reference to preferred
embodiments shown in the accompanying drawings.
Metal Powder for Powder Metallurgy
[0038] First, a metal powder for powder metallurgy according to the
invention will be described.
[0039] In powder metallurgy, a sintered body having a desired shape
can be obtained by molding a composition containing a metal powder
for powder metallurgy and a binder into a desired shape, followed
by degreasing and firing. According to such a powder metallurgy
technique, an advantage that a sintered body with a complicated and
fine shape can be produced in a near-net shape (a shape close to a
final shape) as compared with the other metallurgy techniques is
obtained.
[0040] With respect to the metal powder for powder metallurgy to be
used in the powder metallurgy, an attempt to increase the density
of a sintered body to be produced by appropriately changing the
composition thereof has been made. However, in the sintered body,
pores are liable to be generated, and therefore, in order to obtain
mechanical properties comparable to those of ingot materials, it
was necessary to further increase the density of the sintered
body.
[0041] For example, in the past, the obtained sintered body was
further subjected to an additional treatment such as a hot
isostatic pressing treatment (HIP treatment) to increase the
density. However, such an additional treatment requires much time,
labor, and cost, and therefore becomes an obstacle to the expansion
of the application of the sintered body.
[0042] In consideration of the above-mentioned problems, the
present inventors have made intensive studies to find conditions
for obtaining a sintered body having a high density without
performing an additional treatment. As a result, they found that
the density of a sintered body can be increased by optimizing the
structure of each particle contained in a metal powder, and thus
completed the invention.
[0043] Specifically, the metal powder for powder metallurgy
according to this embodiment is a metal powder including particles,
which contain Fe as a principal component, Cr in a proportion of
0.2% by mass or more and 35% by mass or less, Si in a proportion of
0.2% by mass or more and 3% by mass or less, C in a proportion of
0.005% by mass or more and 2% by mass or less, the below-mentioned
first element in a proportion of 0.01% by mass or more and 0.5% by
mass or less, and the below-mentioned second element in a
proportion of 0.01% by mass or more and 0.5% by mass or less,
wherein the content of Cr on the surface of each particle is 0.2%
by atom or more and 15% by atom or less and is 70% or more and 170%
or less the content of Cr at a depth of 60 nm from the surface of
the particle. According to such a metal powder, as a result of
optimizing the chemical composition and the particle structure, the
densification during sintering can be particularly enhanced. As a
result, a sintered body having a sufficiently high density can be
produced without performing an additional treatment.
[0044] Such a sintered body has excellent mechanical properties.
Due to this, the sintered body can be widely applied also to, for
example, machine parts, structural parts, and the like, to which an
external force is applied.
[0045] The first element is one element selected from the group
consisting of the following seven elements: Ti, V, Y, Zr, Nb, Hf,
and Ta, and the second element is one element selected from the
group consisting of the above-mentioned seven elements and having a
higher group number in the periodic table than that of the first
element or one element selected from the group consisting of the
above-mentioned seven elements and having the same group number in
the periodic table as that of the element selected as the first
element and a higher period number in the periodic table than that
of the first element.
[0046] Hereinafter, the configuration of the metal powder for
powder metallurgy according to this embodiment will be described in
further detail. In the following description, the "metal powder for
powder metallurgy" is sometimes simply referred to as "metal
powder", and each of the multiple particles constituting the metal
powder for powder metallurgy is sometimes simply referred to as
"particle".
Structure of Particle
[0047] First, the structure of the particle of the metal powder for
powder metallurgy according to this embodiment will be
described.
[0048] FIG. 1 is a view schematically showing the cross sections of
particles contained in the embodiment of a metal powder for powder
metallurgy according to the invention, and FIG. 2 is an enlarged
view of an area A of the cross section of the particle shown in
FIG. 1 and is a view for illustrating a manner of performing an
analysis in the depth direction by Auger electron spectroscopy in
combination with sputtering of the surface of the particle.
[0049] When the content of Cr on the surface of a particle 1 is
represented by Cr(0), and the content of Cr at a depth of 60 nm
from the surface of the particle 1 is represented by Cr(60), the
Cr(0) is 0.2% by atom or more and 15% by atom or less and is 70% or
more and 170% or less the Cr(60).
[0050] It can be said that the particle 1 satisfying such
conditions has a relatively fixed Cr content from the surface to
the depth of 60 nm. Such a particle 1 has a passivation film
derived from a Cr oxide whose thickness is small to some extent,
and therefore, the decrease in the sinterability of the particle 1
due to the passivation film can be suppressed. As a result, the
densification during sintering of the particles 1 is achieved, and
therefore, a sintered body having a high density can be produced
without performing an additional treatment.
[0051] When the Cr(0) is less than the above lower limit or the
ratio of the Cr(0) to the Cr(60) is less than the above lower
limit, the oxidation resistance on the surface of the particle 1 is
deteriorated. If the oxidation resistance is deteriorated, the
surface of the particle 1 is liable to be oxidized by the change in
environment. At this time, the oxidation of the surface of the
particle 1 is liable to occur unevenly among the particles 1, and
therefore, the sinterability varies among the particles 1 resulting
in deterioration of the densification of the sintered body. On the
other hand, if the Cr(0) exceeds the above upper limit or the ratio
of the Cr(0) to the Cr(60) exceeds the above upper limit, the
thickness of the passivation film becomes too large. Therefore, the
passivation film inhibits the sintering of the particles 1
resulting in deterioration of the densification of the sintered
body.
[0052] The possibility that a region at a depth of 60 nm from the
surface of the particle 1 contributes to sintering even when the
metal powder is fired is considered to be low. In other words, the
chemical composition at a depth of 60 nm is considered to be close
to the chemical composition in the inside of the particle 1. Due to
this, the fact that the Cr(0) is substantially the same as the
Cr(60) means that a significantly thick passivation film is not
formed on the surface of the particle 1, and this is considered to
be the reason why the sinterability of the particle 1 is
enhanced.
[0053] The Cr(0) and the Cr(60) can be obtained by an analysis in
the depth direction by Auger electron spectroscopy in combination
with sputtering. In this analysis, the particle 1 is irradiated
with an electron beam while allowing ions to collide with the
surface of the particle 1 to gradually strip an atomic layer, and
atoms are identified and quantitatively determined based on the
kinetic energy of Auger electrons emitted from the particle 1. Due
to this, by converting a time required for sputtering into the
thickness of the atomic layer stripped by the sputtering, the
relationship between the depth from the surface of the particle 1
and the compositional ratio of the particle 1 can be obtained.
[0054] The relationship between the depth and the compositional
ratio as described above can be obtained within the range of a
depth of several hundred nanometers from the surface. At this time,
it is only necessary that at least the Cr(0) and the Cr(60) satisfy
the relationship described above, and for example, the content of
Cr at a depth of 30 nm from the surface of the particle 1 may
deviate from the range that the content is 70% or more and 170% or
less the Cr(60).
[0055] The Cr(0) may be 0.2% by atom or more and 15% by atom or
less, but is preferably set to 0.5% by atom or more and 13% by atom
or less.
[0056] The Cr(0) may be 70% or more and 170% or less the Cr(60),
but is preferably set to 80% or more and 150% or less the
Cr(60).
[0057] Still further, when the content of Cr in the whole particle
1 is represented by Cr(w), the content of Cr on the surface of the
particle 1 (Cr(0)) preferably satisfies the following relationship:
Cr(0)<Cr(w), more preferably satisfies the following
relationship: Cr(0)<0.8.times.Cr(w). By satisfying the
relationship as described above, the content of Cr on the surface
of the particle 1 can be made lower than the content of Cr in the
whole particle 1. According to this, as compared with the thickness
of the passivation film converted from the chemical composition of
the whole particle 1, the thickness of the passivation film formed
on the surface of the particle 1 can be prevented from excessively
increasing, and therefore, the sinterability of the particle 1 can
be particularly enhanced.
[0058] The content of Cr in the whole particle 1 can be determined
by an analytical method described below.
[0059] Further, when the content of Si on the surface of the
particle 1 is represented by Si(0), and the content of Si at a
depth of 60 nm from the surface of the particle 1 is represented by
Si(60), the Si(0) is preferably 155% or more and 800% or less, more
preferably 200% or more and 500% or less the Si(60).
[0060] In the particle 1 satisfying such conditions, the content of
Si on the surface is 1.55 times or more higher than the content of
Si in the inside (at a depth of 60 nm). It can be said that in such
a particle 1, Si is segregated on the surface. Si is considered to
be present in the form of, for example, silicon oxide on the
surface of the particle 1. Further, Si functions as a deoxidizing
element which suppresses the oxidation of Fe or Cr, and therefore,
the generation of iron oxide or chromium oxide on the surface of
the particle 1 can be suppressed. Further, even in the case where
oxygen is newly supplied when the particle 1 is sintered, the
generation of a large amount of iron oxide or chromium oxide can be
suppressed. As a result, the particle 1 has more excellent
sinterability and a sintered body having a higher density can be
produced.
[0061] Si present on the surface of the particle 1 functions to
suppress the increase in the size of crystal grains when the metal
powder is fired. Due to this, finer crystals are formed, and thus,
a sintered body having excellent mechanical properties can be
produced.
[0062] The Si(0) is preferably 15% by atom or more and 50% by atom
or less, more preferably 25% by atom or more and 45% by atom or
less.
[0063] The particle 1 satisfying such conditions can suppress the
generation of a large amount of iron oxide or chromium oxide. Due
to this, the particle 1 has more excellent sinterability and a
sintered body having a higher density can be produced.
[0064] On the other hand, on the surface of the particle 1, Si is
segregated, however, if a large amount of Si in the form of silicon
oxide is present, in the same manner as iron oxide or chromium
oxide, firing of the metal powder may be inhibited.
[0065] In view of this, when the content of 0 on the surface of the
particle 1 is represented by O(0), the O(0) is preferably 0.05
times or more and 0.4 times or less, more preferably 0.1 times or
more and 0.35 times or less the Si(0).
[0066] In the case where the ratio of O(0) to Si(0) falls within
the above range, even if Si is segregated on the surface of the
particle 1, the ratio of Si present in the form of silicon oxide is
sufficiently decreased. Therefore, by making the ratio of O(0) to
Si(0) fall within the above range, the deoxidizing effect of Si can
be more reliably exhibited while suppressing the decrease in
sinterability due to the presence of a large amount of silicon
oxide. As a result, the particle 1 having particularly high
sinterability is obtained, and by using the metal powder containing
the particle 1, a sintered body having a high density can be
produced.
[0067] The above-mentioned Si(0), Si(60), and O(0) can be also
obtained by an analysis in the depth direction by Auger electron
spectroscopy in combination with sputtering in the same manner as
the Cr(0) and Cr(60).
[0068] By increasing the density of a sintered body in this manner,
a sintered body having excellent mechanical properties is obtained.
Such a sintered body can be widely applied also to, for example,
machine parts, structural parts, and the like, to which an external
force is applied.
Chemical Composition of Particle
[0069] Next, one example of the chemical composition of the whole
particle 1 will be described.
[0070] Fe is a component (principal component) whose content is the
highest in the chemical composition of the particle 1 and has a
great influence on the properties of the sintered body. The content
of Fe in the whole particle 1 is 50% by mass or more.
Cr
[0071] Cr (chromium) is an element which provides corrosion
resistance to a sintered body to be produced. By using the metal
powder containing Cr, a sintered body capable of maintaining high
mechanical properties over a long period of time is obtained.
[0072] The content of Cr in the particle 1 is set to 0.2% by mass
or more and 35% by mass or less, but is set to preferably 2% by
mass or more and 32% by mass or less, more preferably 6% by mass or
more and 30% by mass or less.
[0073] If the content of Cr is less than the above lower limit, the
corrosion resistance of a sintered body to be produced may be
insufficient depending on the overall composition. On the other
hand, if the content of Cr exceeds the above upper limit, the
sinterability is deteriorated depending on the overall composition
so that it may become difficult to increase the density of the
sintered body.
Ni
[0074] Ni (nickel) is an element which provides corrosion
resistance and heat resistance to a sintered body to be produced as
needed.
[0075] The content of Ni in the particle 1 is set to preferably 41%
by mass or less, more preferably 10% by mass or more and 39% by
mass or less, further more preferably 12% by mass or more and 27%
by mass or less. By setting the content of Ni within the above
range, a sintered body which maintains excellent mechanical
properties over a long period of time can be obtained.
[0076] If the content of Ni is less than the above lower limit, the
corrosion resistance and the heat resistance of a sintered body to
be produced may not be sufficiently enhanced depending on the
overall composition. On the other hand, if the content of Ni
exceeds the above upper limit, the corrosion resistance and the
heat resistance may be deteriorated instead.
[0077] In the case where Ni or Mo is contained in the particle 1,
the content of Cr may be appropriately changed according to the
content of Ni or Mo.
[0078] For example, in the case where the content of Ni is 7% by
mass or more and 22% by mass or less and the content of Mo is less
than 1.2% by mass, the content of Cr is more preferably 18% by mass
or more and 20% by mass or less. On the other hand, in the case
where the content of Ni is 10% by mass or more and 22% by mass or
less and the content of Mo is 1.2% by mass or more and 5% by mass
or less, the content of Cr is more preferably 16% by mass or more
and less than 18% by mass.
[0079] Further, in the case where the content of Ni is 0.05% by
mass or more and 0.6% by mass or less, the content of Cr is more
preferably 10% by mass or more and 18% by mass or less.
Si
[0080] Si (silicon) is an element which provides corrosion
resistance and high mechanical properties to a sintered body to be
produced, and by using the metal powder containing Si, a sintered
body capable of maintaining high mechanical properties over a long
period of time can be obtained.
[0081] The content of Si in the metal powder is set to 0.2% by mass
or more and 3% by mass or less, but is set to preferably 0.4% by
mass or more and 1.5% by mass or less, more preferably 0.5% by mass
or more and 1% by mass or less.
[0082] If the content of Si is less than the above lower limit, the
effect of the addition of Si is weakened depending on the overall
composition so that the corrosion resistance and the mechanical
properties of a sintered body to be produced may be deteriorated.
On the other hand, if the content of Si exceeds the above upper
limit, the amount of Si is too large depending on the overall
composition so that the corrosion resistance and the mechanical
properties may be deteriorated instead.
C
[0083] By using C (carbon) in combination with the first element
and the second element, a carbide or the like of the first element
and a carbide or the like of the second element are generated as
described above. According to this, a sintered body having a high
density can be obtained as described above.
[0084] The content of C in the particle 1 is set to 0.005% by mass
or more and 2% by mass or less, but is set to preferably 0.01% by
mass or more and 1.5% by mass or less, more preferably 0.02% by
mass or more and 1% by mass or less.
[0085] If the content of C is less than the above lower limit, it
is difficult to generate sufficient amounts of a carbide or the
like of the first element and a carbide or the like of the second
element depending on the overall composition, and therefore, the
densification of the sintered body may be insufficient. On the
other hand, if the content of C exceeds the above upper limit, the
amount of C with respect to the amounts of the first element and
the second element is too large depending on the overall
composition, and therefore, the sinterability of the particle 1 may
be deteriorated instead.
[0086] In the case where Ni is contained in the particle 1, the
content of C may be appropriately changed according to the content
of Ni.
[0087] For example, in the case where the content of Ni is 7% by
mass or more and 22% by mass or less, the content of C is more
preferably 0.005% by mass or more and 0.3% by mass or less.
[0088] Further, in the case where the content of Ni is 0.05% by
mass or more and 0.6% by mass or less, the content of C is more
preferably 0.15% by mass or more and 1.2% by mass or less.
[0089] In the case where Ni is contained in the particle 1, the
content of Ni is preferably set to 0.05% by mass or more and 22% by
mass or less. By adding Ni to the particle 1, the corrosion
resistance and the heat resistance of a sintered body to be
produced can be further enhanced.
[0090] If the content of Ni is less than the above lower limit, the
corrosion resistance and the heat resistance of a sintered body to
be produced may not be sufficiently enhanced depending on the
overall composition. On the other hand, if the content of Ni
exceeds the above upper limit, the corrosion resistance and the
heat resistance may be deteriorated instead.
First Element and Second Element
[0091] The first element and the second element each deposit a
carbide or an oxide (hereinafter also collectively referred to as
"carbide or the like"). It is considered that this deposited
carbide or the like inhibits the significant growth of crystal
grains when the metal powder is sintered. As a result, as described
above, it becomes difficult to generate pores in a sintered body,
and also the increase in the size of crystal grains is prevented,
and thus, a sintered body having a high density and excellent
mechanical properties is obtained.
[0092] In addition, although a detailed description will be given
later, the deposited carbide or the like promotes the accumulation
of silicon oxide at a crystal grain boundary, and as a result, the
sintering is promoted and the density is increased while preventing
the increase in the size of crystal grains.
[0093] The first element and the second element are two elements
selected from the group consisting of the following seven elements:
Ti, V, Y, Zr, Nb, Hf, and Ta, but preferably include an element
belonging to group IIIA or group IVA in the long periodic table
(Ti, Y, Zr, or Hf). By including an element belonging to group IIIA
or group IVA as at least one of the first element and the second
element, oxygen contained as an oxide in the metal powder is
removed and the sinterability of the metal powder can be
particularly enhanced.
[0094] The first element is only required to be one element
selected from the group consisting of the following seven elements:
Ti, V, Y, Zr, Nb, Hf, and Ta as described above, but is preferably
an element belonging to group IIIA or group IVA in the long
periodic table in the group consisting of the above-mentioned seven
elements. An element belonging to group IIIA or group IVA removes
oxygen contained as an oxide in the metal powder (functions as a
deoxidizing element) and therefore can particularly enhance the
sinterability of the metal powder. According to this, the
concentration of oxygen remaining in the crystal grains after
sintering can be decreased. As a result, the content of oxygen in
the sintered body can be decreased, and the density can be
increased. Further, these elements are elements having high
activity, and therefore are considered to cause rapid atomic
diffusion. Accordingly, this atomic diffusion acts as a driving
force, and thereby a distance between particles of the metal powder
is efficiently decreased and a neck is formed between the
particles, so that the densification of a molded body is promoted.
As a result, the density of the sintered body can be further
increased.
[0095] On the other hand, the second element is only required to be
one element selected from the group consisting of the following
seven elements: Ti, V, Y, Zr, Nb, Hf, and Ta and different from the
first element as described above, but is preferably an element
belonging to group VA in the long periodic table in the group
consisting of the above-mentioned seven elements. An element
belonging to group V A particularly efficiently deposits the
above-mentioned carbide or the like, and therefore, can efficiently
inhibit the significant growth of crystal grains during sintering.
As a result, the formation of fine crystal grains is promoted, and
thus, the density of the sintered body can be increased and also
the mechanical properties of the sintered body can be enhanced.
[0096] Incidentally, by the combination of the first element with
the second element composed of the elements as described above, the
effects of the respective elements are exhibited without inhibiting
each other. Due to this, the metal powder containing such a first
element and a second element enables the production of a sintered
body having a particularly high density.
[0097] More preferably, a combination of an element belonging to
group IVA as the first element with Nb as the second element is
adopted.
[0098] Further, more preferably, a combination of Zr or Hf as the
first element with Nb as the second element is adopted.
[0099] By adopting such a combination, the above-mentioned effect
becomes more prominent.
[0100] In the case where the first element is particularly Zr, Zr
is a ferrite forming element, and therefore deposits a
body-centered cubic lattice phase. This body-centered cubic lattice
phase has more excellent sinterability than the other crystal
lattice phases, and therefore contributes to the densification of a
sintered body.
[0101] The atomic radius of Zr is slightly larger than that of Fe.
Specifically, the atomic radius of Fe is about 0.117 nm, and the
atomic radius of Zr is about 0.145 nm. Therefore, Zr is
solid-dissolved in Fe, but is not completely solid-dissolved
therein, and part of Zr is deposited as a carbide or the like.
According to this, an appropriate amount of a carbide or the like
is deposited, and therefore, the increase in the size of crystal
grains can be effectively prevented while promoting the sintering
and increasing the density.
[0102] In the case where the second element is particularly Nb, the
atomic radius of Nb is slightly larger than that of Fe, but
slightly smaller than that of Zr. Specifically, the atomic radius
of Fe is about 0.117 nm, and the atomic radius of Nb is about 0.134
nm. Therefore, Nb is solid-dissolved in Fe, but is not completely
solid-dissolved therein, and part of Nb is deposited as a carbide
or the like. According to this, an appropriate amount of a carbide
or the like is deposited, and therefore, the increase in the size
of crystal grains can be effectively prevented while promoting the
sintering and increasing the density.
[0103] The content of the first element in the metal powder is set
to 0.01% by mass or more and 0.5% by mass or less, but is set to
preferably 0.03% by mass or more and 0.4% by mass or less, more
preferably 0.05% by mass or more and 0.3% by mass or less. If the
content of the first element is less than the above lower limit,
the effect of the addition of the first element is weakened
depending on the overall composition so that the density of a
sintered body to be produced is not sufficiently increased. On the
other hand, if the content of the first element exceeds the above
upper limit, the amount of the first element is too large depending
on the overall composition so that the ratio of the above-mentioned
carbide or the like is too high, and therefore, the densification
is deteriorated instead.
[0104] The content of the second element in the metal powder is set
to 0.01% by mass or more and 0.5% by mass or less, but is set to
preferably 0.03% by mass or more and 0.4% by mass or less, more
preferably 0.05% by mass or more and 0.3% by mass or less. If the
content of the second element is less than the above lower limit,
the effect of the addition of the second element is weakened
depending on the overall composition so that the density of a
sintered body to be produced is not sufficiently increased. On the
other hand, if the content of the second element exceeds the above
upper limit, the amount of the second element is too large
depending on the overall composition so that the ratio of the
above-mentioned carbide or the like is too high, and therefore, the
densification is deteriorated instead.
[0105] Further, as described above, each of the first element and
the second element deposits a carbide or the like, however, in the
case where an element belonging to group III A or group IVA is
selected as the first element as described above and an element
belonging to group VA is selected as the second element as
described above, it is presumed that when the metal powder is
sintered, the timing when a carbide or the like of the first
element is deposited and the timing when a carbide or the like of
the second element is deposited differ moderately from each other.
It is considered that due to the difference in timing when a
carbide or the like is deposited in this manner, sintering
gradually proceeds so that the generation of pores is prevented,
and thus, a dense sintered body is obtained. That is, it is
considered that by the presence of both of the carbide or the like
of the first element and the carbide or the like of the second
element, the increase in the size of crystal grains can be
suppressed while increasing the density of the sintered body.
[0106] Due to such a difference in timing, the carbide or the like
of the first element and the carbide or the like of the second
element deposited in the particle 1 are mutually exclusively
present. That is, the carbide or the like of the first element and
the carbide or the like of the second element are less likely to be
deposited at the same site, and most of them are deposited apart
from each other. Then, by the presence of both of the carbide or
the like of the first element and the carbide or the like of the
second element in this manner, when the particles 1 are sintered,
the increase in the size of crystal grains is more reliably
prevented, and thus, the density of the sintered body can be
increased.
[0107] Further, since the carbide or the like of the first element
and the carbide or the like of the second element are deposited
apart from each other, an effect of preventing the increase in the
size of crystal grains is uniformly exhibited in the particle 1. In
view of this, the densification of the sintered body is
particularly promoted.
[0108] In addition, it is considered that in the particle 1, the
carbide or the like of the first element and the carbide or the
like of the second element act as "nuclei", and the accumulation of
silicon oxide occurs. By the accumulation of silicon oxide at a
crystal grain boundary, the concentration of oxides inside the
crystal is decreased, and therefore, sintering is promoted. As a
result, it is considered that the densification of the sintered
body is further promoted when the particles 1 are sintered.
[0109] When such particles 1 are subjected to powder metallurgy, a
sintered body can be densified, and therefore, a sintered body
having a high density can be produced without performing an
additional treatment. It is considered that when the particles 1
are subjected to powder metallurgy, the carbide or the like moves
to a metal crystal grain boundary in a sintered body. Then, the
carbide or the like having moved to the triple point of a crystal
grain boundary suppresses the crystal growth at this point (a flux
pinning effect). As a result, the significant growth of crystal
grains is suppressed, and thus, a sintered body having finer
crystals is obtained. Such a sintered body has particularly high
mechanical properties.
[0110] Further, it is preferred to set the ratio of the content of
the first element to the content of the second element in
consideration of the mass number of the first element and the mass
number of the second element.
[0111] Specifically, when a value obtained by dividing the content
E1 (mass %) of the first element by the mass number of the first
element is represented by X1 and a value obtained by dividing the
content E2 (mass %) of the second element by the mass number of the
second element is represented by X2, X1/X2 is preferably 0.3 or
more and 3 or less, more preferably 0.5 or more and 2 or less,
further more preferably 0.75 or more and 1.3 or less. By setting
the ratio X1/X2 within the above range, the balance between the
deposition amount of the carbide or the like of the first element
and the deposition amount of the carbide or the like of the second
element can be optimized. According to this, pores remaining in a
molded body can be eliminated as if they were swept out
sequentially from the inside, and therefore, pores generated in a
sintered body can be minimized. Accordingly, a metal powder capable
of producing a sintered body having a high density and excellent
mechanical properties can be obtained by setting the ratio X1/X2
within the above range.
[0112] Here, with respect to a specific example of the combination
of the first element with the second element, based on the
above-mentioned range of the ratio X1/X2, the ratio (E1/E2) of the
content E1 of the first element to the content E2 of the second
element is calculated.
[0113] For example, in the case where the first element is Zr and
the second element is Nb, since the mass number of Zr is 91.2 and
the mass number of Nb is 92.9, E1/E2 is preferably 0.29 or more and
2.95 or less, more preferably 0.49 or more and 1.96 or less.
[0114] In the case where the first element is Hf and the second
element is Nb, since the mass number of Hf is 178.5 and the mass
number of Nb is 92.9, E1/E2 is preferably 0.58 or more and 5.76 or
less, more preferably 0.96 or more and 3.84 or less.
[0115] In the case where the first element is Ti and the second
element is Nb, since the mass number of Ti is 47.9 and the mass
number of Nb is 92.9, E1/E2 is preferably 0.15 or more and 1.55 or
less, more preferably 0.26 or more and 1.03 or less.
[0116] In the case where the first element is Nb and the second
element is Ta, since the mass number of Nb is 92.9 and the mass
number of Ta is 180.9, E1/E2 is preferably 0.15 or more and 1.54 or
less, more preferably 0.26 or more and 1.03 or less.
[0117] In the case where the first element is Y and the second
element is Nb, since the mass number of Y is 88.9 and the mass
number of Nb is 92.9, E1/E2 is preferably 0.29 or more and 2.87 or
less, more preferably 0.48 or more and 1.91 or less.
[0118] In the case where the first element is V and the second
element is Nb, since the mass number of V is 50.9 and the mass
number of Nb is 92.9, E1/E2 is preferably 0.16 or more and 1.64 or
less, more preferably 0.27 or more and 1.10 or less.
[0119] In the case where the first element is Ti and the second
element is Zr, since the mass number of Ti is 47.9 and the mass
number of Zr is 91.2, E1/E2 is preferably 0.16 or more and 1.58 or
less, more preferably 0.26 or more and 1.05 or less.
[0120] In the case where the first element is Zr and the second
element is Ta, since the mass number of Zr is 91.2 and the mass
number of Ta is 180.9, E1/E2 is preferably 0.15 or more and 1.51 or
less, more preferably 0.25 or more and 1.01 or less.
[0121] In the case where the first element is Zr and the second
element is V, since the mass number of Zr is 91.2 and the mass
number of V is 50.9, E1/E2 is preferably 0.54 or more and 5.38 or
less, more preferably 0.90 or more and 3.58 or less.
[0122] Also in the case of a combination other than the
above-mentioned combinations, E1/E2 can be calculated in the same
manner as described above.
[0123] The sum of the content E1 of the first element and the
content E2 of the second element is preferably 0.05% by mass or
more and 0.8% by mass or less, more preferably 0.10% by mass or
more and 0.6% by mass or less, further more preferably 0.12% by
mass or more and 0.24% by mass or less. By setting the sum of the
content of the first element and the content of the second element
within the above range, the densification of a sintered body to be
produced becomes necessary and sufficient.
[0124] When the ratio of the sum of the content of the first
element and the content of the second element to the content of Si
is represented by (E1+E2)/Si, (E1+E2)/Si is preferably 0.1 or more
and 0.7 or less, more preferably 0.15 or more and 0.6 or less,
further more preferably 0.2 or more and 0.5 or less in terms of
mass ratio. By setting the ratio (E1+E2)/Si within the above range,
a decrease in the toughness or the like when Si is added is
sufficiently compensated by the addition of the first element and
the second element. As a result, a metal powder capable of
producing a sintered body which has excellent mechanical properties
such as toughness in spite of having a high density and also has
excellent corrosion resistance attributed to Si is obtained. In
addition, in the particle 1, necessary and sufficient accumulation
of silicon oxide occurs by using the carbide or the like of the
first element and the carbide or the like of the second element as
nuclei, and in the case where an element such as Ni is contained in
the particle 1 other than Fe and Cr, an oxidation reaction of such
an element is easily suppressed. Therefore, also from this
viewpoint, the sinterability of the particle 1 is enhanced, and
thus, a sintered body having a higher density, excellent mechanical
properties, and excellent corrosion resistance can be obtained.
[0125] Further, when the ratio of the sum of the content of the
first element and the content of the second element to the content
of C is represented by (E1+E2)/C, (E1+E2)/C is preferably 1 or more
and 16 or less, more preferably 2 or more and 13 or less, further
more preferably 3 or more and 10 or less. By setting the ratio
(E1+E2)/C within the above range, an increase in the hardness and
the suppression of a decrease in the toughness when C is added, and
an increase in the density brought about by the addition of the
first element and the second element can be achieved. As a result,
the particle 1 capable of producing a sintered body which has
excellent mechanical properties such as tensile strength and
toughness is obtained.
[0126] The metal powder is only required to contain two elements
selected from the group consisting of the above-mentioned seven
elements, but may further contain an element which is selected from
this group and is different from these two elements. That is, the
metal powder may contain three or more elements selected from the
group consisting of the above-mentioned seven elements. According
to this, the above-mentioned effect can be further enhanced, which
slightly varies depending on the combination of the elements to be
contained.
Another Element
[0127] The particle 1 may contain, other than the above-mentioned
elements, at least one element of W, Co, Mn, Mo, Cu, N, and S as
needed. These elements may be inevitably contained in some
cases.
[0128] W is an element which enhances the heat resistance of a
sintered body to be produced.
[0129] The content of W in the particle 1 is set to 0.5% by mass or
more and 20% by mass or less, but is set to preferably 1% by mass
or more and 10% by mass or less, more preferably 5% by mass or more
and 7% by mass or less. If the content of W is less than the above
lower limit, the heat resistance and the sintered body cannot be
sufficiently enhanced depending on the overall composition, and for
example, when a tool is produced by using the obtained sintered
body, the hardness, softening resistance, and abrasion resistance
of the tool at a high temperature may be deteriorated. On the other
hand, if the content of W exceeds the above upper limit, the
mechanical properties such as toughness of the sintered body may be
deteriorated depending on the overall composition, and for example,
a problem such as a chipping may occur in the tool.
[0130] Co is an element which enhances the heat resistance of a
sintered body to be produced.
[0131] The content of Co in the particle 1 is not particularly
limited, but is preferably 3% by mass or more and 12% by mass or
less, more preferably 4.5% by mass or more and 10.5% by mass or
less. By setting the content of Co within the above range, the heat
resistance of a sintered body to be produced can be further
enhanced without causing a large decrease in the density of the
sintered body. In particular, the decrease in the hardness or the
softness resistance at a high temperature can be suppressed, and
therefore, for example, when a tool is produced by using the
obtained sintered body, a high-speed tool which can be cut at a
higher speed can be easily produced.
[0132] Mn is an element which provides corrosion resistance and
high mechanical properties to a sintered body to be produced.
[0133] The content of Mn in the particle 1 is not particularly
limited, but is preferably 0.01% by mass or more and 3% by mass or
less, more preferably 0.05% by mass or more and 1% by mass or less.
By setting the content of Mn within the above range, a sintered
body having a higher density and excellent mechanical properties is
obtained.
[0134] If the content of Mn is less than the above lower limit, the
corrosion resistance and the mechanical properties of a sintered
body to be produced may not be sufficiently enhanced depending on
the overall composition. On the other hand, if the content of Mn
exceeds the above upper limit, the corrosion resistance and the
mechanical properties may be deteriorated instead depending on the
overall composition.
[0135] Mo is an element which enhances the corrosion resistance of
a sintered body to be produced.
[0136] The content of Mo in the particle 1 is not particularly
limited, but is preferably 1% by mass or more and 5% by mass or
less, more preferably 1.2% by mass or more and 4% by mass or less,
further more preferably 2% by mass or more and 3% by mass or less.
By setting the content of Mo within the above range, the corrosion
resistance of a sintered body to be produced can be further
enhanced without causing a large decrease in the density of the
sintered body.
[0137] Cu is an element which enhances the corrosion resistance of
a sintered body to be produced.
[0138] The content of Cu in the particle 1 is not particularly
limited, but is preferably 5% by mass or less, more preferably 1%
by mass or more and 4% by mass or less. By setting the content of
Cu within the above range, the corrosion resistance of a sintered
body to be produced can be further enhanced without causing a large
decrease in the density of the sintered body.
[0139] In the case where the content of Ni is 0.05% by mass or more
and 0.6% by mass or less, the content of Cu is preferably less than
1% by mass or less, more preferably less than 0.1% by mass or less.
Further, in this case, it is more preferred that the particle 1
substantially contains no Cu (the content of Cu is set to less than
0.01% by mass) excluding the amount of Cu which is inevitably
contained. The detailed reasons therefor have not been known,
however, this is due to the fear that by the incorporation of Cu,
the effect brought about by the first element and the second
element as described above may be weakened.
[0140] N is an element which enhances the mechanical properties
such as proof stress of a sintered body to be produced.
[0141] The content of N in the particle 1 is not particularly
limited, but is preferably 0.03% by mass or more and 1% by mass or
less, more preferably 0.08% by mass or more and 0.3% by mass or
less, further more preferably 0.1% by mass or more and 0.25% by
mass or less. By setting the content of N within the above range,
the mechanical properties such as proof stress of a sintered body
to be produced can be further enhanced without causing a large
decrease in the density of the sintered body.
[0142] In order to produce the particles 1 to which N is added, for
example, a method using a nitrided starting material, a method of
introducing nitrogen gas into a molten metal, a method of
performing a nitriding treatment of a produced metal powder, or the
like is used.
[0143] S is an element which enhances the machinability of a
sintered body to be produced.
[0144] The content of S in the particle 1 is not particularly
limited, but is preferably 0.5% by mass or less, more preferably
0.01% by mass or more and 0.3% by mass or less. By setting the
content of S within the above range, the machinability of a
sintered body to be produced can be further enhanced without
causing a large decrease in the density of the sintered body.
Accordingly, the obtained sintered body can be cut out into a
desired shape by performing a machining process.
[0145] To the particle 1, B, Se, Te, Pd, Al, or the like may be
added other than the above-mentioned elements. At this time, the
contents of these elements are not particularly limited, but the
content of each element is preferably less than 0.1% by mass, and
also the total content of these elements is preferably less than
0.2% by mass. These elements may be inevitably contained in some
cases.
[0146] The particle 1 may contain impurities. Examples of the
impurities include all elements other than the above-mentioned
elements, and examples thereof include Li, Be, Na, Mg, P, K, Ca,
Sc, Zn, Ga, Ge, Ag, In, Sn, Sb, Os, Ir, Pt, Au, and Bi. The
incorporation amounts of these impurity elements are preferably
such that the content of each of the impurity elements is less than
the content of each of the above-mentioned constituent elements of
the particle 1. Further, the incorporation amount of these impurity
elements is preferably set such that the content of each of the
impurity elements is less than 0.03% by mass, more preferably less
than 0.02% by mass. Further, the total content of these impurity
elements is set to preferably less than 0.3% by mass, more
preferably less than 0.2% by mass. These elements do not inhibit
the effect as described above as long as the contents thereof are
within the above range, and therefore may be intentionally added to
the particle 1.
[0147] Meanwhile, O (oxygen) may also be intentionally added to or
inevitably mixed in the metal powder, however, the amount thereof
is preferably about 0.8% by mass or less, more preferably about
0.5% by mass or less. By controlling the amount of oxygen in the
metal powder within the above range, the sinterability is enhanced,
and thus, a sintered body having a high density and excellent
mechanical properties is obtained. Incidentally, the lower limit
thereof is not particularly set, but is preferably 0.03% by mass or
more from the viewpoint of ease of mass production or the like.
[0148] The chemical composition of the particle 1 can be determined
by, for example, Iron and steel--Atomic absorption spectrometric
method specified in JIS G 1257 (2000), Iron and steel--ICP atomic
emission spectrometric method specified in JIS G 1258 (2007), Iron
and steel--Method for spark discharge atomic emission spectrometric
analysis specified in JIS G 1253 (2002), Iron and steel--Method for
X-ray fluorescence spectrometric analysis specified in JIS G 1256
(1997), gravimetric, titrimetric, and absorption spectrometric
methods specified in JIS G 1211 to G 1237, or the like.
Specifically, for example, an optical emission spectrometer for
solids (spark optical emission spectrometer, model: SPECTROLAB,
type: LAVMB08A) manufactured by SPECTRO Analytical Instruments GmbH
or an ICP device (model: CIROS-120) manufactured by Rigaku
Corporation can be used.
[0149] Incidentally, the methods specified in JIS G 1211 to G 1237
are as follows.
[0150] JIS G 1211 (2011): Iron and steel--Methods for determination
of carbon content
[0151] JIS G 1212 (1997): Iron and steel--Methods for determination
of silicon content
[0152] JIS G 1213 (2001): Iron and steel--Methods for determination
of manganese content
[0153] JIS G 1214 (1998): Iron and steel--Methods for determination
of phosphorus content
[0154] JIS G 1215 (2010): Iron and steel--Methods for determination
of sulfur content
[0155] JIS G 1216 (1997): Iron and steel--Methods for determination
of nickel content
[0156] JIS G 1217 (2005): Iron and steel--Methods for determination
of chromium content
[0157] JIS G 1218 (1999): Iron and steel--Methods for determination
of molybdenum content
[0158] JIS G 1219 (1997): Iron and steel--Methods for determination
of copper content
[0159] JIS G 1220 (1994): Iron and steel--Methods for determination
of tungsten content
[0160] JIS G 1221 (1998): Iron and steel--Methods for determination
of vanadium content
[0161] JIS G 1222 (1999): Iron and steel--Methods for determination
of cobalt content
[0162] JIS G 1223 (1997): Iron and steel--Methods for determination
of titanium content
[0163] JIS G 1224 (2001): Iron and steel--Methods for determination
of aluminum content
[0164] JIS G 1225 (2006): Iron and steel--Methods for determination
of arsenic content
[0165] JIS G 1226 (1994): Iron and steel--Methods for determination
of tin content
[0166] JIS G 1227 (1999): Iron and steel--Methods for determination
of boron content
[0167] JIS G 1228 (2006): Iron and steel--Methods for determination
of nitrogen content
[0168] JIS G 1229 (1994): Steel--Methods for determination of lead
content
[0169] JIS G 1232 (1980): Methods for determination of zirconium in
steel
[0170] JIS G 1233 (1994): Steel--Method for determination of
selenium content
[0171] JIS G 1234 (1981): Methods for determination of tellurium in
steel
[0172] JIS G 1235 (1981): Methods for determination of antimony in
iron and steel
[0173] JIS G 1236 (1992): Method for determination of tantalum in
steel
[0174] JIS G 1237 (1997): Iron and steel--Methods for determination
of niobium content
[0175] Further, when C (carbon) and S (sulfur) are determined,
particularly, an infrared absorption method after combustion in a
current of oxygen (after combustion in a high-frequency induction
heating furnace) specified in JIS G 1211 (2011) is also used.
Specifically, a carbon-sulfur analyzer, CS-200 manufactured by LECO
Corporation can be used.
[0176] Further, when N (nitrogen) and O (oxygen) are determined,
particularly, a method for determination of nitrogen content in
iron and steel specified in JIS G 1228 (2006) and a method for
determination of oxygen content in metallic materials specified in
JIS Z 2613 (2006) are also used. Specifically, an oxygen-nitrogen
analyzer, TC-300/EF-300 manufactured by LECO Corporation can be
used.
[0177] Further, the particle 1 as described above is preferably
contained in the metal powder for powder metallurgy as much as
possible, and specifically, the particle 1 is contained therein in
an amount of preferably 50% by number or more, more preferably 60%
by number or more. According to such a metal powder for powder
metallurgy, the effect as described above brought about by the
particle 1 is more reliably exhibited.
[0178] The above-mentioned ratio can be obtained by arbitrarily
extracting 20 or more particles in the metal powder for powder
metallurgy and counting the particles 1 as described above.
[0179] The average particle diameter of the metal powder for powder
metallurgy of the invention is preferably 0.5 .mu.m or more and 30
.mu.m or less, more preferably 1 .mu.m or more and 20 .mu.n or
less, further more preferably 2 .mu.n or more and 10 .mu.n or less.
By using the metal powder for powder metallurgy having such a
particle diameter, pores remaining in a sintered body are extremely
reduced, and therefore, a sintered body having a particularly high
density and particularly excellent mechanical properties can be
produced.
[0180] The average particle diameter can be obtained as a particle
diameter when the cumulative amount obtained by cumulating the
percentages of the particles from the smaller diameter side reaches
50% in a cumulative particle size distribution on amass basis
obtained by laser diffractometry.
[0181] If the average particle diameter of the metal powder for
powder metallurgy is less than the above lower limit, the
moldability is deteriorated in the case where the shape is
difficult to mold, and therefore, the sintered density may be
decreased. On the other hand, if the average particle diameter of
the metal powder exceeds the above upper limit, spaces between the
particles become larger during molding, and therefore, the sintered
density may be decreased also in this case.
[0182] The particle size distribution of the metal powder for
powder metallurgy is preferably as narrow as possible.
Specifically, when the average particle diameter of the metal
powder for powder metallurgy is within the above range, the maximum
particle diameter of the metal powder is preferably 200 .mu.m or
less, more preferably 150 .mu.m or less. By controlling the maximum
particle diameter of the metal powder for powder metallurgy within
the above range, the particle size distribution of the metal powder
for powder metallurgy can be made narrower, and thus, the density
of the sintered body can be further increased.
[0183] Here, the "maximum particle diameter" refers to a particle
diameter when the cumulative amount obtained by cumulating the
percentages of the particles from the smaller diameter side reaches
99.9% in a cumulative particle size distribution on amass basis
obtained by laser diffractometry.
[0184] When the minor axis of each particle of the metal powder for
powder metallurgy is represented by S (.mu.m) and the major axis
thereof is represented by L (.mu.m), the average of the aspect
ratio defined by S/L is preferably about 0.4 or more and 1 or less,
more preferably about 0.7 or more and 1 or less. The metal powder
for powder metallurgy having an aspect ratio within this range has
a shape relatively close to a spherical shape, and therefore, the
packing factor when the metal powder is molded is increased. As a
result, the density of the sintered body can be further
increased.
[0185] Here, the "major axis" is the maximum length in the
projected image of the particle, and the "minor axis" is the
maximum length in the direction perpendicular to the major axis.
Incidentally, the average of the aspect ratio can be obtained as
the average of the measured aspect ratios of 100 or more
particles.
[0186] The tap density of the metal powder for powder metallurgy of
the invention is preferably 3.5 g/cm.sup.3 or more, more preferably
4 g/cm.sup.3 or more. According to the metal powder for powder
metallurgy having such a high tap density, when a molded body is
obtained, the interparticle packing efficiency is particularly
increased. Therefore, a particularly dense sintered body can be
obtained in the end.
[0187] The specific surface area of the metal powder for powder
metallurgy of the invention is not particularly limited, but is
preferably 0.1 m.sup.2/g or more, more preferably 0.2 m.sup.2/g or
more. According to the metal powder for powder metallurgy having
such a large specific surface area, a surface activity (surface
energy) is increased so that it is possible to easily sinter the
metal powder even if less energy is applied. Therefore, when a
molded body is sintered, a difference in sintering rate hardly
occurs between the inner side and the outer side of the molded
body, and thus, the decrease in the sintered density due to the
pores remaining inside the molded body can be suppressed.
Method for Producing Sintered Body
[0188] Next, a method for producing a sintered body using such a
metal powder for powder metallurgy according to the invention will
be described.
[0189] The method for producing a sintered body includes (A) a
composition preparation step in which a composition for producing a
sintered body is prepared, (B) a molding step in which a molded
body is produced, (C) a degreasing step in which a degreasing
treatment is performed, and (D) a firing step in which firing is
performed. Hereinafter, the respective steps will be described
sequentially.
(A) Composition Preparation Step
[0190] First, the metal powder for powder metallurgy according to
the invention and a binder are prepared, and these materials are
kneaded using a kneader, whereby a kneaded material (composition)
is obtained.
[0191] In this kneaded material (an embodiment of the compound
according to the invention), the metal powder for powder metallurgy
is uniformly dispersed.
[0192] The metal powder for powder metallurgy according to the
invention is produced by, for example, any of a variety of
powdering methods such as an atomization method (such as a water
atomization method, a gas atomization method, or a spinning water
atomization method), a reducing method, a carbonyl method, and a
pulverization method.
[0193] Among these, the metal powder for powder metallurgy
according to the invention is preferably a metal powder produced by
an atomization method, more preferably a metal powder produced by a
water atomization method or a spinning water atomization method.
The atomization method is a method in which a molten metal (metal
melt) is caused to collide with a fluid (liquid or gas) sprayed at
a high speed to atomize the metal melt into a fine powder and also
to cool the fine powder, whereby a metal powder is produced. By
producing the metal powder for powder metallurgy through such an
atomization method, an extremely fine powder can be efficiently
produced. Further, the shape of the particle of the obtained powder
is closer to a spherical shape by the action of surface tension.
Due to this, when the metal powder is molded, a molded body having
a high packing factor is obtained. That is, a powder capable of
producing a sintered body having a high density can be obtained. In
addition, the cooling rate of the metal melt is very high, and
therefore, the particle 1 in which the second region P2 and the
third region P3 are more uniformly distributed can be obtained.
[0194] In the case where a water atomization method is used as the
atomization method, the pressure of water (hereinafter referred to
as "atomization water") to be sprayed to the molten metal is not
particularly limited, but is set to preferably about 75 MPa or more
and 120 MPa or less (750 kgf/cm.sup.2 or more and 1200 kgf/cm.sup.2
or less), more preferably about 90 MPa or more and 120 MPa or less
(900 kgf/cm.sup.2 or more and 1200 kgf/cm.sup.2 or less).
[0195] The temperature of the atomization water is also not
particularly limited, but is preferably set to about 1.degree. C.
or higher and 20.degree. C. or lower.
[0196] The atomization water is often sprayed in a cone shape such
that it has a vertex on the falling path of the metal melt and the
outer diameter gradually decreases downward. In this case, the
vertex angle .theta. of the cone formed by the atomization water is
preferably about 10.degree. or more and 40.degree. or less, more
preferably about 15.degree. or more and 35.degree. or less.
According to this, a metal powder for powder metallurgy having a
composition as described above can be reliably produced.
[0197] Further, by using a water atomization method (particularly,
a spinning water atomization method), the metal melt can be cooled
particularly quickly. Due to this, a powder having high quality can
be obtained in a wide alloy composition range.
[0198] The cooling rate when cooling the metal melt in the
atomization method is preferably 1.times.10.sup.4.degree. C./s or
more, more preferably 1.times.10.sup.5.degree. C./s or more. By the
quick cooling in this manner, a homogeneous metal powder for powder
metallurgy can be obtained. As a result, a sintered body having
high quality can be obtained. Incidentally, the volume occupancy of
the crystalline material as described above in the particle 1
varies depending on the conditions (for example, the alloy
composition, the production conditions, etc.) when the metal powder
for powder metallurgy is produced. For example, in the case where
the cooling rate is increased (for example, in the case of
1.times.10.sup.5.degree. C./s or more), the volume of an amorphous
material or a metal glass tends to slightly increase, and in the
case where the cooling rate is decreased (for example, in the case
of 1.times.10.sup.4.degree. C./s or more and less than
1.times.10.sup.5.degree. C./s), the volume of a crystalline
material tends to slightly increase.
[0199] The thus obtained metal powder for powder metallurgy may be
classified as needed. Examples of the classification method include
dry classification such as sieving classification, inertial
classification, and centrifugal classification, and wet
classification such as sedimentation classification.
[0200] Examples of the binder include polyolefins such as
polyethylene, polypropylene, and ethylene-vinyl acetate copolymers,
acrylic resins such as polymethyl methacrylate and polybutyl
methacrylate, styrenic resins such as polystyrene, polyesters such
as polyvinyl chloride, polyvinylidene chloride, polyamide,
polyethylene terephthalate, and polybutylene terephthalate, various
resins such as polyether, polyvinyl alcohol, polyvinylpyrrolidone,
and copolymers thereof, and various organic binders such as various
waxes, paraffins, higher fatty acids (such as stearic acid), higher
alcohols, higher fatty acid esters, and higher fatty acid amides.
These can be used alone or by mixing two or more types thereof.
[0201] The content of the binder is preferably about 2% by mass or
more and 20% by mass or less, more preferably about 5% by mass or
more and 10% by mass or less with respect to the total amount of
the kneaded material. By setting the content of the binder within
the above range, a molded body can be formed with good moldability,
and also the density is increased, whereby the stability of the
shape of the molded body and the like can be particularly enhanced.
Further, according to this, a difference in size between the molded
body and the degreased body, that is, so-called a shrinkage ratio
is optimized, whereby a decrease in the dimensional accuracy of the
finally obtained sintered body can be prevented. That is, a
sintered body having a high density and high dimensional accuracy
can be obtained.
[0202] In the kneaded material, a plasticizer may be added as
needed. Examples of the plasticizer include phthalate esters (such
as DOP, DEP, and DBP), adipate esters, trimellitate esters, and
sebacate esters. These can be used alone or by mixing two or more
types thereof.
[0203] Further, in the kneaded material, other than the metal
powder for powder metallurgy, the binder, and the plasticizer, for
example, any of a variety of additives such as a lubricant, an
antioxidant, a degreasing accelerator, and a surfactant can be
added as needed.
[0204] The kneading conditions vary depending on the respective
conditions such as the metal composition or the particle diameter
of the metal powder for powder metallurgy to be used, the
composition of the binder, and the blending amount thereof.
However, for example, the kneading temperature can be set to about
50.degree. C. or higher and 200.degree. C. or lower, and the
kneading time can be set to about 15 minutes or more and 210
minutes or less.
[0205] Further, the kneaded material is formed into a pellet (small
particle) as needed. The particle diameter of the pellet is set to,
for example, about 1 mm or more and 15 mm or less.
[0206] Incidentally, depending on the molding method described
below, in place of the kneaded material, a granulated powder may be
produced. The kneaded material, the granulated powder, and the like
are examples of the composition to be subjected to the molding step
described below.
[0207] The embodiment of the granulated powder according to the
invention is directed to a granulated powder obtained by binding a
plurality of metal particles to one another with a binder by
subjecting the metal powder for powder metallurgy according to the
invention to a granulation treatment.
[0208] Examples of the binder to be used for producing the
granulated powder include polyolefins such as polyethylene,
polypropylene, and ethylene-vinyl acetate copolymers, acrylic
resins such as polymethyl methacrylate and polybutyl methacrylate,
styrenic resins such as polystyrene, polyesters such as polyvinyl
chloride, polyvinylidene chloride, polyamide, polyethylene
terephthalate, and polybutylene terephthalate, various resins such
as polyether, polyvinyl alcohol, polyvinylpyrrolidone, and
copolymers thereof, and various organic binders such as various
waxes, paraffins, higher fatty acids (such as stearic acid), higher
alcohols, higher fatty acid esters, and higher fatty acid amides.
These can be used alone or by mixing two or more types thereof.
[0209] Among these, as the binder, a binder containing a polyvinyl
alcohol or polyvinylpyrrolidone is preferred. These binder
components have a high binding ability, and therefore can
efficiently form the granulated powder even in a relatively small
amount. Further, the thermal decomposability thereof is also high,
and therefore, the binder can be reliably decomposed and removed in
a short time during degreasing and firing.
[0210] The content of the binder is preferably about 0.2% by mass
or more and 10% by mass or less, more preferably about 0.3% by mass
or more and 5% by mass or less, further more preferably about 0.3%
by mass or more and 2% by mass or less with respect to the total
amount of the granulated powder. By setting the content of the
binder within the above range, the granulated powder can be
efficiently formed while preventing significantly large particles
from being formed or the metal particles which are not granulated
from remaining in a large amount. Further, since the moldability is
improved, the stability of the shape of the molded body and the
like can be particularly enhanced. Further, by setting the content
of the binder within the above range, a difference in size between
the molded body and the degreased body, that is, so-called a
shrinkage ratio is optimized, whereby a decrease in the dimensional
accuracy of the finally obtained sintered body can be
prevented.
[0211] Further, in the granulated powder, any of a variety of
additives such as a plasticizer, a lubricant, an antioxidant, a
degreasing accelerator, and a surfactant may be added as
needed.
[0212] Examples of the granulation treatment include a spray drying
method, a tumbling granulation method, a fluidized bed granulation
method, and a tumbling fluidized bed granulation method.
[0213] In the granulation treatment, a solvent which dissolves the
binder is used as needed. Examples of the solvent include inorganic
solvents such as water and carbon tetrachloride, and organic
solvents such as ketone-based solvents, alcohol-based solvents,
ether-based solvents, cellosolve-based solvents, aliphatic
hydrocarbon-based solvents, aromatic hydrocarbon-based solvents,
aromatic heterocyclic compound-based solvents, amide-based
solvents, halogen compound-based solvents, ester-based solvents,
amine-based solvents, nitrile-based solvents, nitro-based solvents,
and aldehyde-based solvents, and one type or a mixture of two or
more types selected from these solvents is used.
[0214] The average particle diameter of the granulated powder is
not particularly limited, but is preferably about 10 .mu.m or more
and 200 .mu.m or less, more preferably about 20 .mu.m or more and
100 .mu.m or less, further more preferably about 25 .mu.m or more
and 60 .mu.m or less. The granulated powder having such a particle
diameter has favorable fluidity, and can more faithfully reflect
the shape of a molding die.
[0215] The average particle diameter can be obtained as a particle
diameter when the cumulative amount obtained by cumulating the
percentages of the particles from the smaller diameter side reaches
50% in a cumulative particle size distribution on amass basis
obtained by laser diffractometry.
(B) Molding Step
[0216] Subsequently, the kneaded material or the granulated powder
is molded, whereby a molded body having the same shape as that of a
target sintered body is produced.
[0217] The method for producing a molded body (molding method) is
not particularly limited, and for example, any of a variety of
molding methods such as a powder compacting (compression molding)
method, a metal injection molding (MIM) method, and an extrusion
molding method can be used.
[0218] The molding conditions in the case of a powder compacting
method among these methods are preferably such that the molding
pressure is about 200 MPa or more and 1000 MPa or less (2
t/cm.sup.2 or more and 10 t/cm.sup.2 or less), which vary depending
on the respective conditions such as the composition and the
particle diameter of the metal powder for powder metallurgy to be
used, the composition of the binder, and the blending amount
thereof.
[0219] The molding conditions in the case of a metal injection
molding method are preferably such that the material temperature is
about 80.degree. C. or higher and 210.degree. C. or lower, and the
injection pressure is about 50 MPa or more and 500 MPa or less (0.5
t/cm.sup.2 or more and 5 t/cm.sup.2 or less), which vary depending
on the respective conditions.
[0220] The molding conditions in the case of an extrusion molding
method are preferably such that the material temperature is about
80.degree. C. or higher and 210.degree. C. or lower, and the
extrusion pressure is about 50 MPa or more and 500 MPa or less (0.5
t/cm.sup.2 or more and 5 t/cm.sup.2 or less), which vary depending
on the respective conditions.
[0221] The thus obtained molded body is in a state where the binder
is uniformly distributed in spaces between the particles of the
metal powder.
[0222] The shape and size of the molded body to be produced are
determined in anticipation of shrinkage of the molded body in the
subsequent degreasing step and firing step.
(C) Degreasing Step
[0223] Subsequently, the thus obtained molded body is subjected to
a degreasing treatment (binder removal treatment), whereby a
degreased body is obtained.
[0224] Specifically, the binder is decomposed by heating the molded
body, whereby the binder is removed from the molded body. In this
manner, the degreasing treatment is performed.
[0225] Examples of the degreasing treatment include a method of
heating the molded body and a method of exposing the molded body to
a gas capable of decomposing the binder.
[0226] In the case of using a method of heating the molded body,
the conditions for heating the molded body are preferably such that
the temperature is about 100.degree. C. or higher and 750.degree.
C. or lower and the time is about 0.1 hours or more and 20 hours or
less, and more preferably such that the temperature is about
150.degree. C. or higher and 600.degree. C. or lower and the time
is about 0.5 hours or more and 15 hours or less, which slightly
vary depending on the composition and the blending amount of the
binder. According to this, the degreasing of the molded body can be
necessarily and sufficiently performed without sintering the molded
body. As a result, it is possible to reliably prevent the binder
component from remaining inside the degreased body in a large
amount.
[0227] The atmosphere when the molded body is heated is not
particularly limited, and an atmosphere of a reducing gas such as
hydrogen, an atmosphere of an inert gas such as nitrogen or argon,
an atmosphere of an oxidative gas such as air, a reduced pressure
atmosphere obtained by reducing the pressure of such an atmosphere,
or the like can be used.
[0228] Examples of the gas capable of decomposing the binder
include ozone gas.
[0229] Incidentally, by dividing this degreasing step into a
plurality of steps in which the degreasing conditions are
different, and performing the plurality of steps, the binder in the
molded body can be more rapidly decomposed and removed so that the
binder does not remain in the molded body.
[0230] Further, according to need, the degreased body may be
subjected to a machining process such as grinding, polishing, or
cutting. The degreased body has a relatively low hardness and
relatively high plasticity, and therefore, the machining process
can be easily performed while preventing the degreased body from
losing its shape. According to such a machining process, a sintered
body having high dimensional accuracy can be easily obtained in the
end.
(D) Firing Step
[0231] The degreased body obtained in the above step (C) is fired
in a firing furnace, whereby a sintered body is obtained.
[0232] By this firing, in the metal powder for powder metallurgy,
diffusion occurs at the boundary surface between the particles,
resulting in sintering. At this time, by the mechanism as described
above, the degreased body is rapidly sintered. As a result, a
sintered body which is dense and has a high density on the whole is
obtained.
[0233] The firing temperature varies depending on the composition,
the particle diameter, and the like of the metal powder for powder
metallurgy used in the production of the molded body and the
degreased body, but is set to, for example, about 980.degree. C. or
higher and 1330.degree. C. or lower, and preferably set to about
1050.degree. C. or higher and 1260.degree. C. or lower.
[0234] Further, the firing time is set to 0.2 hours or more and 7
hours or less, but is preferably set to about 1 hour or more and 6
hours or less.
[0235] In the firing step, the firing temperature or the
below-described firing atmosphere may be changed in the middle of
the step.
[0236] By setting the firing conditions within such a range, it is
possible to sufficiently sinter the entire degreased body while
preventing the sintering from proceeding excessively to cause
oversintering and increase the size of the crystal structure. As a
result, a sintered body having a high density and particularly
excellent mechanical properties can be obtained.
[0237] Further, since the firing temperature is a relatively low
temperature, it is easy to control the heating temperature in the
firing furnace to be a fixed temperature, and therefore, it is also
easy to maintain the temperature of the degreased body at a fixed
temperature. As a result, a more homogeneous sintered body can be
produced.
[0238] Further, since the firing temperature as described above is
a temperature which can be sufficiently realized using a common
firing furnace, and therefore, an inexpensive firing furnace can be
used, and also the running cost can be kept low. In other words, in
the case where the temperature exceeds the above-mentioned firing
temperature, it is necessary to employ an expensive firing furnace
using a special heat resistant material, and also the running cost
may be increased.
[0239] The atmosphere when performing firing is not particularly
limited, however, in consideration of prevention of significant
oxidation of the metal powder, an atmosphere of a reducing gas such
as hydrogen, an atmosphere of an inert gas such as argon, a reduced
pressure atmosphere obtained by reducing the pressure of such an
atmosphere, or the like is preferably used.
[0240] The thus obtained sintered body has a high density and
excellent mechanical properties. That is, a sintered body produced
by molding a composition containing the metal powder for powder
metallurgy according to the invention and a binder, followed by
degreasing and sintering has a higher relative density than a
sintered body obtained by sintering a metal powder in the related
art. Therefore, according to the invention, a sintered body having
a high density which could not be obtained unless an additional
treatment such as an HIP treatment is performed can be realized
without performing an additional treatment.
[0241] Specifically, according to the invention, for example, the
relative density can be expected to be increased by 2% or more as
compared with the related art, which slightly varies depending on
the composition of the metal powder for powder metallurgy.
[0242] As a result, the relative density of the obtained sintered
body can be expected to be, for example, 97% or more (preferably
98% or more, more preferably 98.5% or more). The sintered body
having a relative density within such a range has excellent
mechanical properties comparable to those of ingot materials
although it has a shape as close as possible to a desired shape by
using a powder metallurgy technique, and therefore, the sintered
body can be applied to a variety of machine parts, structural
parts, and the like with virtually no post-processing.
[0243] Further, the tensile strength and the 0.2% proof stress of a
sintered body produced by molding a composition containing the
metal powder for powder metallurgy according to the invention and a
binder, followed by degreasing and sintering are higher than those
of a sintered body obtained by performing sintering in the same
manner using a metal powder in the related art. This is considered
to be because by optimizing the alloy composition and the particle
structure, the sinterability of the metal powder is enhanced, and
thus, the mechanical properties of a sintered body to be produced
using the metal powder are enhanced.
[0244] Further, the sintered body produced as described above has a
high surface hardness. Specifically, in the case of, for example, a
composition according to austenite stainless steel, the Vickers
hardness of the surface of the sintered body is expected to be 140
or more and 500 or less, also preferably expected to be 150 or more
and 400 or less, which slightly varies depending on the composition
of the metal powder for powder metallurgy. In the case of, for
example, a composition according to martensite stainless steel, the
Vickers hardness of the surface of the sintered body is expected to
be 570 or more and 1200 or less, also preferably expected to be 600
or more and 1000 or less. The sintered body having such a hardness
has particularly high durability.
[0245] The sintered body has a sufficiently high density and
excellent mechanical properties even without performing an
additional treatment, however, in order to further increase the
density and enhance the mechanical properties, a variety of
additional treatments may be performed.
[0246] As the additional treatment, for example, an additional
treatment of increasing the density such as the HIP treatment
described above may be performed, and also a variety of quenching
treatments, a variety of sub-zero treatments, a variety of
tempering treatments, and the like may be performed. These
additional treatments may be performed alone or two or more
treatments thereof may be performed in combination.
[0247] In the firing step and a variety of additional treatments
described above, a light element in the metal powder (in the
sintered body) is volatilized, and the composition of the finally
obtained sintered body slightly changes from the composition of the
metal powder in some cases.
[0248] For example, the content of C in the final sintered body may
change within the range of 5% or more and 100% or less (preferably
within the range of 30% or more and 100% or less) of the content of
C in the metal powder for powder metallurgy, which varies depending
on the conditions for the step or the conditions for the
treatment.
[0249] Also the content of 0 in the final sintered body may change
within the range of 1% or more and 50% or less (preferably within
the range of 3% or more and 50% or less) of the content of 0 in the
metal powder for powder metallurgy, which varies depending on the
conditions for the step or the conditions for the treatment.
[0250] On the other hand, as described above, the produced sintered
body may be subjected to an HIP treatment as part of the additional
treatments to be performed as needed, however, even if the HIP
treatment is performed, a sufficient effect is not exhibited in
many cases. In the HIP treatment, the density of the sintered body
can be further increased, however, in the first place, the density
of the sintered body obtained according to the invention has
already been sufficiently increased at the end of the firing step.
Therefore, even if the HIP treatment is further performed,
densification hardly proceeds any further.
[0251] In addition, in the HIP treatment, it is necessary to apply
pressure to a material to be treated through a pressure medium, and
therefore, the material to be treated may be contaminated, the
composition or the physical properties of the material to be
treated may unintentionally change accompanying the contamination,
or the color of the material to be treated may change accompanying
the contamination. Further, by the application of pressure,
residual stress is generated or increased in the material to be
treated, and a problem such as a change in the shape or a decrease
in the dimensional accuracy may occur as the residual stress is
released over time.
[0252] On the other hand, according to the invention, a sintered
body having a sufficiently high density can be produced without
performing such an HIP treatment, and therefore, a sintered body
having an increased density and also an increased strength can be
obtained in the same manner as in the case of performing an HIP
treatment. Such a sintered body is less contaminated and
discolored, and also an unintended change in the composition or
physical properties, or the like occurs less, and also a problem
such as a change in the shape or a decrease in the dimensional
accuracy occurs less. Therefore, according to the invention, a
sintered body having high mechanical strength and dimensional
accuracy, and excellent durability can be efficiently produced.
[0253] Further, the sintered body produced according to the
invention requires almost no additional treatments for enhancing
the mechanical properties, and therefore, the composition and the
crystal structure tend to become uniform in the entire sintered
body. Due to this, the sintered body has high structural anisotropy
and therefore has excellent durability against a load from every
direction regardless of its shape.
[0254] Incidentally, it is confirmed that in the thus produced
sintered body, the porosity near the surface thereof is often
relatively lower than inside the sintered body. The reason therefor
is not clear, however, one of the reasons is that by the addition
of the first element and the second element, the sintering reaction
more easily proceeds near the surface of the molded body than
inside the molded body.
[0255] Specifically, when the porosity near the surface of the
sintered body is represented by A1 and the porosity inside the
sintered body is represented by A2, A2-A1 is preferably 0.1% or
more and 3% or less, more preferably 0.2% or more and 2% or less.
The sintered body showing the value of A2-A1 within the above range
not only has necessary and sufficient mechanical strength, but also
can easily flatten the surface. That is, by polishing the surface
of such a sintered body, a surface having high specularity can be
obtained.
[0256] Such a sintered body having high specularity not only has
high mechanical strength, but also has excellent aesthetic
properties. Therefore, such a sintered body is favorably used also
for application requiring excellent aesthetic appearance.
[0257] Incidentally, the porosity A1 near the surface of the
sintered body refers to a porosity in a 25-.mu.m radius region
centered on the position at a depth of 50 .mu.m from the surface of
the cross section of the sintered body. Further, the porosity A2
inside the sintered body refers to a porosity in a 25-.mu.m radius
region centered on the position at a depth of 300 .mu.m from the
surface of the cross section of the sintered body. These porosities
are values obtained by observing the cross section of the sintered
body with a scanning electron microscope and dividing the area of
pores present in the region by the area of the region.
[0258] Hereinabove, the metal powder for powder metallurgy, the
compound, the granulated powder, and the sintered body according to
the invention have been described with reference to preferred
embodiments, however, the invention is not limited thereto.
[0259] Further, the sintered body according to the invention is
used for, for example, parts for transport machinery such as parts
for automobiles, parts for bicycles, parts for railroad cars, parts
for ships, parts for airplanes, and parts for space transport
machinery (such as rockets); parts for electronic devices such as
parts for personal computers and parts for mobile phone terminals;
parts for electrical devices such as refrigerators, washing
machines, and cooling and heating machines; parts for machines such
as machine tools and semiconductor production devices; parts for
plants such as atomic power plants, thermal power plants,
hydroelectric power plants, oil refinery plants, and chemical
complexes; parts for timepieces, metallic tableware, jewels,
ornaments such as frames for glasses, and all other sorts of
structural parts.
EXAMPLES
[0260] Next, Examples of the invention will be described.
1. Production of Sintered Body (Zr--Nb Based)
Sample No. 1
[0261] (1) First, a metal powder having a composition shown in
Table 1 produced by a water atomization method was prepared. This
metal powder had an average particle diameter of 4.05 .mu.m, a tap
density of 4.15 g/cm.sup.3, and a specific surface area of 0.21
m.sup.2/g.
[0262] The composition of the powder shown in Table 1 was
identified and quantitatively determined by an inductively coupled
high-frequency plasma optical emission spectrometry (ICP analysis
method). In the ICP analysis, an ICP device (model: CIROS-120)
manufactured by Rigaku Corporation was used. Further, in the
identification and determination of C, a carbon-sulfur analyzer
(CS-200) manufactured by LECO Corporation was used. Further, in the
identification and determination of 0, an oxygen-nitrogen analyzer
(TC-300/EF-300) manufactured by LECO Corporation was used.
[0263] (2) Subsequently, the metal powder and a mixture (organic
binder) of polypropylene and a wax were weighed at a mass ratio of
9:1 and mixed with each other, whereby a mixed starting material
was obtained.
[0264] (3) Subsequently, this mixed starting material was kneaded
using a kneader, whereby a compound was obtained.
[0265] (4) Subsequently, this compound was molded using an
injection molding device under the following molding conditions,
whereby a molded body was produced.
[0266] Molding Conditions [0267] Material temperature: 150.degree.
C. [0268] Injection pressure: 11 MPa (110 kgf/cm.sup.2)
[0269] (5) Subsequently, the obtained molded body was subjected to
a heat treatment (degreasing treatment) under the following
degreasing conditions, whereby a degreased body was obtained.
[0270] Degreasing Conditions [0271] Degreasing temperature:
500.degree. C. [0272] Degreasing time: 1 hour (retention time at
the degreasing temperature) [0273] Degreasing atmosphere: nitrogen
atmosphere
[0274] (6) Subsequently, the obtained degreased body was fired
under the following firing conditions, whereby a sintered body was
obtained. The shape of the sintered body was determined to be a
cylinder with a diameter of 10 mm and a thickness of 5 mm.
[0275] Firing Conditions [0276] Firing temperature: 1200.degree. C.
[0277] Firing time: 3 hours (retention time at the firing
temperature) [0278] Firing atmosphere: argon atmosphere
Sample Nos. 2 to 30
[0279] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 1, respectively. The
sintered body of sample No. 30 was obtained by performing an HIP
treatment under the following conditions after firing. Further, the
sintered bodies of sample Nos. 18 to 20 were obtained by using the
metal powder produced by a gas atomization method, respectively,
and indicated by "gas" in the column of Remarks in Table 1.
[0280] HIP Treatment Conditions [0281] Heating temperature:
1100.degree. C. [0282] Heating time: 2 hours [0283] Applied
pressure: 100 MPa
TABLE-US-00001 [0283] TABLE 1 Metal powder for powder metallurgy
Alloy composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample
Cr Ni Si C (Zr) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % --
mass % -- -- -- No. 1 Example 16.43 12.48 0.73 0.018 0.09 0.07 2.11
0.06 0.28 remainder 1.29 0.16 0.22 8.89 No. 2 Example 17.12 12.63
0.58 0.023 0.07 0.05 2.43 0.12 0.31 remainder 1.40 0.12 0.21 5.22
No. 3 Example 17.87 13.24 0.65 0.029 0.05 0.09 2.04 0.07 0.42
remainder 0.56 0.14 0.22 4.83 No. 4 Example 16.19 14.71 0.84 0.011
0.05 0.05 2.89 0.08 0.25 remainder 1.00 0.10 0.12 9.09 No. 5
Example 17.55 13.88 0.75 0.026 0.09 0.10 2.61 0.11 0.36 remainder
0.90 0.19 0.25 7.31 No. 6 Example 16.79 11.58 0.52 0.068 0.12 0.03
2.74 0.12 0.22 remainder 4.00 0.15 0.29 2.21 No. 7 Example 17.49
13.21 0.69 0.054 0.03 0.12 2.15 0.79 0.41 remainder 0.25 0.15 0.22
2.78 No. 8 Example 16.88 14.15 0.77 0.024 0.24 0.09 2.23 0.28 0.48
remainder 2.67 0.33 0.43 13.75 No. 9 Example 17.32 12.65 0.48 0.021
0.08 0.26 2.81 0.17 0.29 remainder 0.31 0.34 0.71 16.19 No. 10
Example 17.25 12.87 0.35 0.065 0.09 0.05 2.15 0.35 0.62 remainder
1.80 0.14 0.40 2.15 No. 11 Example 17.66 12.55 0.96 0.017 0.07 0.07
2.24 0.05 0.25 remainder 1.00 0.14 0.15 8.24 No. 12 Example 16.87
12.91 1.12 0.025 0.15 0.19 2.13 0.05 0.25 remainder 0.79 0.34 0.30
13.60 No. 13 Example 16.78 12.19 0.54 0.019 0.36 0.42 2.25 0.07
0.58 remainder 0.86 0.78 1.44 41.05 No. 14 Example 16.77 12.89 0.91
0.024 0.14 0.17 2.13 0.05 0.25 remainder 0.82 0.31 0.34 12.92 No.
15 Example 16.47 12.57 0.87 0.023 0.13 0.15 2.04 0.05 0.25
remainder 0.87 0.28 0.32 12.17 No. 16 Example 16.75 12.58 0.68
0.007 0.05 0.09 2.84 0.12 0.28 remainder 0.56 0.14 0.21 20.00 No.
17 Example 17.22 13.54 0.84 0.152 0.08 0.05 2.84 0.12 0.28
remainder 1.60 0.13 0.15 0.86 No. 18 Example 16.45 12.55 0.72 0.023
0.08 0.08 1.95 0.08 0.07 remainder 1.00 0.16 0.22 6.96 gas No. 19
Example 17.26 12.57 0.59 0.032 0.07 0.06 2.64 0.02 0.08 remainder
1.17 0.13 0.22 4.06 gas No. 20 Example 17.64 13.41 0.63 0.015 0.04
0.07 2.04 0.06 0.10 remainder 0.57 0.11 0.17 7.33 gas No. 21
Compar- 16.34 12.84 0.75 0.025 0.00 0.07 2.36 0.11 0.29 remainder
0.00 0.07 0.09 2.80 ative Example No. 22 Compar- 17.22 13.32 0.79
0.032 0.05 0.00 2.28 0.09 0.31 remainder -- 0.05 0.06 1.56 ative
Example No. 23 Compar- 16.75 14.23 0.75 0.015 0.00 0.00 2.33 0.12
0.33 remainder -- 0.00 0.00 0.00 ative Example No. 24 Compar- 16.43
12.45 0.88 0.021 0.68 0.07 2.58 0.11 0.38 remainder 9.71 0.75 0.85
35.71 ative Example No. 25 Compar- 16.35 13.04 0.66 0.035 0.06 0.71
2.36 0.05 0.41 remainder 0.08 0.77 1.17 22.00 ative Example No. 26
Compar- 17.56 13.25 0.15 0.011 0.06 0.07 2.77 0.11 0.27 remainder
0.86 0.13 0.87 11.82 ative Example No. 27 Compar- 17.63 13.54 0.95
0.061 0.04 0.08 2.89 0.32 0.45 remainder 0.50 0.12 0.06 1.97 ative
Example No. 28 Compar- 17.56 13.25 0.66 0.002 0.01 0.01 2.77 0.11
0.27 remainder 1.00 0.02 0.03 10.00 ative Example No. 29 Compar-
17.56 13.25 0.35 0.380 0.22 0.07 2.68 0.24 0.45 remainder 3.14 0.29
0.83 0.76 ative Example No. 30 Compar- 17.34 12.84 0.75 0.025 0.00
0.07 2.36 0.11 0.29 remainder -- 0.07 0.09 2.80 HIP ative treatment
Example
[0284] In Table 1, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0285] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 1 is omitted.
Sample Nos. 31 to 48
[0286] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 2, respectively. The
sintered body of sample No. 48 was obtained by performing an HIP
treatment under the following conditions after firing. Further, the
sintered bodies of sample Nos. 41 to 43 were obtained by using the
metal powder produced by a gas atomization method, respectively,
and indicated by "gas" in the column of Remarks in Table 2.
[0287] HIP Treatment Conditions [0288] Heating temperature:
1100.degree. C. [0289] Heating time: 2 hours [0290] Applied
pressure: 100 MPa
TABLE-US-00002 [0290] TABLE 2 Metal powder for powder metallurgy
Alloy composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample
Cr Ni Si C (Zr) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % --
mass % -- -- -- No. 31 Example 18.94 13.59 0.77 0.048 0.11 0.09
3.48 0.08 0.48 remainder 1.22 0.20 0.26 4.17 No. 32 Example 18.15
14.75 0.51 0.021 0.08 0.08 3.08 0.95 0.42 remainder 1.00 0.16 0.31
7.62 No. 33 Example 19.63 11.39 0.32 0.074 0.09 0.05 3.92 0.35 0.62
remainder 1.80 0.14 0.44 1.89 No. 34 Example 18.67 13.44 0.98 0.065
0.18 0.04 3.32 0.07 0.28 remainder 4.50 0.22 0.22 3.38 No. 35
Example 18.03 14.87 0.51 0.005 0.04 0.08 3.15 0.02 0.35 remainder
0.50 0.12 0.24 24.00 No. 36 Example 19.78 12.35 0.42 0.178 0.09
0.08 3.87 0.35 0.62 remainder 1.13 0.17 0.40 0.96 No. 37 Example
18.65 13.42 0.87 0.061 0.17 0.04 3.29 0.07 0.28 remainder 4.25 0.21
0.24 3.44 No. 38 Example 18.63 13.46 0.94 0.063 0.16 0.05 3.27 0.07
0.28 remainder 3.20 0.21 0.22 3.33 No. 39 Example 22.54 13.59 0.86
0.066 0.08 0.08 0.00 0.09 0.26 remainder 1.00 0.16 0.19 2.42 No. 40
Example 25.41 21.36 1.16 0.053 0.06 0.08 0.00 0.07 0.27 remainder
0.75 0.14 0.12 2.64 No. 41 Example 18.88 13.54 0.87 0.056 0.12 0.11
3.52 0.11 0.12 remainder 1.09 0.23 0.26 4.11 gas No. 42 Example
18.21 14.81 0.48 0.025 0.07 0.09 3.11 0.98 0.11 remainder 0.78 0.16
0.33 6.40 gas No. 43 Example 19.57 11.44 0.31 0.068 0.08 0.06 4.02
0.51 0.16 remainder 1.33 0.14 0.45 2.06 gas No. 44 Compar- 18.87
11.24 0.57 0.056 0.00 0.07 3.47 0.22 0.29 remainder 0.00 0.07 0.12
1.25 ative Example No. 45 Compar- 19.56 14.15 0.79 0.032 0.15 0.00
3.75 0.09 0.31 remainder -- 0.15 0.19 4.69 ative Example No. 46
Compar- 18.78 11.42 0.88 0.012 0.58 0.07 2.58 0.11 0.38 remainder
8.29 0.65 0.74 54.17 ative Example No. 47 Compar- 19.65 14.51 0.66
0.053 0.06 0.89 2.36 0.05 0.41 remainder 0.07 0.95 1.44 17.92 ative
Example No. 48 Compar- 18.87 11.24 0.57 0.056 0.00 0.07 3.47 0.22
0.29 remainder 0.00 0.07 0.12 1.25 HIP ative treatment Example
[0291] In Table 2, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0292] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 2 is omitted.
Sample Nos. 49 to 66
[0293] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 3, respectively. The
sintered body of sample No. 66 was obtained by performing an HIP
treatment under the following conditions after firing. Further, the
sintered bodies of sample Nos. 59 to 61 were obtained by using the
metal powder produced by a gas atomization method, respectively,
and indicated by "gas" in the column of Remarks in Table 3.
[0294] HIP Treatment Conditions [0295] Heating temperature:
1100.degree. C. [0296] Heating time: 2 hours [0297] Applied
pressure: 100 MPa
TABLE-US-00003 [0297] TABLE 3 Metal powder for powder metallurgy
Alloy composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample
Cr Ni Si C (Zr) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % --
mass % -- -- -- No. 49 Example 19.21 8.34 0.62 0.038 0.08 0.06 0.00
0.21 0.48 remainder 1.33 0.14 0.23 3.68 No. 50 Example 19.74 9.56
0.88 0.041 0.05 0.10 0.08 0.04 0.55 remainder 0.50 0.15 0.17 3.66
No. 51 Example 18.30 10.12 0.44 0.019 0.15 0.09 0.05 0.07 0.68
remainder 1.67 0.24 0.55 12.63 No. 52 Example 19.35 8.19 1.05 0.069
0.08 0.06 0.00 0.05 0.18 remainder 1.33 0.14 0.13 2.03 No. 53
Example 19.45 9.65 0.88 0.007 0.05 0.10 0.08 0.00 0.55 remainder
0.50 0.15 0.17 21.43 No. 54 Example 18.25 10.25 0.44 0.256 0.15
0.09 0.05 0.07 0.68 remainder 1.67 0.24 0.55 0.94 No. 55 Example
20.58 21.54 1.15 0.074 0.05 0.09 0.00 1.23 0.75 remainder 0.56 0.14
0.12 1.89 No. 56 Example 20.34 19.25 1.02 0.068 0.05 0.09 0.00 1.23
0.75 remainder 0.56 0.14 0.14 2.06 No. 57 Example 16.58 7.45 0.56
0.128 0.06 0.08 0.05 0.48 0.25 remainder 0.75 0.14 0.25 1.09 No. 58
Example 15.72 10.25 0.36 0.058 0.04 0.09 2.54 0.07 0.21 remainder
0.44 0.13 0.36 2.24 No. 59 Example 19.11 8.43 0.64 0.045 0.07 0.07
0.00 0.23 0.12 remainder 1.00 0.14 0.22 3.11 gas No. 60 Example
19.72 9.65 0.85 0.048 0.06 0.11 0.09 0.05 0.14 remainder 0.55 0.17
0.20 3.54 gas No. 61 Example 18.25 10.21 0.46 0.015 0.12 0.12 0.06
0.09 0.18 remainder 1.00 0.24 0.52 16.00 gas No. 62 Compar- 19.11
8.48 0.74 0.064 0.00 0.05 0.00 0.18 0.28 remainder 0.00 0.05 0.07
0.78 ative Example No. 63 Compar- 18.78 9.77 0.79 0.023 0.08 0.00
0.02 0.09 0.31 remainder -- 0.08 0.10 3.48 ative Example No. 64
Compar- 18.42 8.21 0.39 0.012 0.69 0.07 0.03 0.11 0.38 remainder
9.86 0.76 1.95 62.33 ative Example No. 65 Compar- 19.21 8.55 0.42
0.021 0.06 0.61 0.02 0.15 0.32 remainder 0.10 0.67 1.60 31.90 ative
Example No. 66 Compar- 19.11 8.48 0.74 0.064 0.00 0.05 0.00 0.18
0.28 remainder 0.00 0.05 0.07 0.78 HIP ative treatment Example
[0298] In Table 3, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0299] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 3 is omitted.
Sample No. 67
[0300] (1) First, a metal powder having a composition shown in
Table 4 was produced by a water atomization method in the same
manner as in the case of sample No. 1.
[0301] (2) Subsequently, the metal powder was granulated by a spray
drying method. The binder used at this time was polyvinyl alcohol,
which was used in an amount of 1 part by mass with respect to 100
parts by mass of the metal powder. Further, a solvent (ion
exchanged water) was used in an amount of 50 parts by mass with
respect to 1 part by mass of polyvinyl alcohol. In this manner, a
granulated powder having an average particle diameter of 50 .mu.m
was obtained.
[0302] (3) Subsequently, this granulated powder was subjected to
powder compacting under the following molding conditions. In this
molding, a press molding machine was used. The shape of the molded
body to be produced was determined to be a cube with a side length
of 20 mm.
[0303] Molding Conditions [0304] Material temperature: 90.degree.
C. [0305] Molding pressure: 600 MPa (6 t/cm.sup.2)
[0306] (4) Subsequently, the obtained molded body was subjected to
a heat treatment (degreasing treatment) under the following
degreasing conditions, whereby a degreased body was obtained.
[0307] Degreasing Conditions [0308] Degreasing temperature:
450.degree. C. [0309] Degreasing time: 2 hours (retention time at
the degreasing temperature) [0310] Degreasing atmosphere: nitrogen
atmosphere
[0311] (5) Subsequently, the obtained degreased body was fired
under the following firing conditions, whereby a sintered body was
obtained.
[0312] Firing Conditions [0313] Firing temperature: 1200.degree. C.
[0314] Firing time: 3 hours (retention time at the firing
temperature) [0315] Firing atmosphere: argon atmosphere
Sample Nos. 68 to 85
[0316] Sintered bodies were obtained in the same manner as in the
case of sample No. 67 except that the composition and the like of
the metal powder for powder metallurgy were changed as shown in
Table 4, respectively. The sintered body of sample No. 85 was
obtained by performing an HIP treatment under the following
conditions after firing.
[0317] HIP Treatment Conditions [0318] Heating temperature:
1100.degree. C. [0319] Heating time: 2 hours [0320] Applied
pressure: 100 MPa
TABLE-US-00004 [0320] TABLE 4 Metal powder for powder metallurgy
Alloy composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample
Cr Ni Si C (Zr) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % --
mass % -- -- -- No. 67 Example 16.43 12.48 0.73 0.018 0.09 0.07
2.11 0.06 0.28 remainder 1.29 0.16 0.22 8.89 Powder compacting No.
68 Example 17.12 12.63 0.58 0.023 0.07 0.05 2.43 0.12 0.31
remainder 1.40 0.12 0.21 5.22 Powder compacting No. 69 Example
17.87 13.24 0.65 0.029 0.05 0.09 2.04 0.07 0.42 remainder 0.56 0.14
0.22 4.83 Powder compacting No. 70 Example 16.19 14.71 0.84 0.011
0.05 0.05 2.89 0.08 0.25 remainder 1.00 0.10 0.12 9.09 Powder
compacting No. 71 Example 17.55 13.88 0.75 0.026 0.09 0.10 2.61
0.11 0.36 remainder 0.90 0.19 0.25 7.31 Powder compacting No. 72
Example 16.79 11.58 0.52 0.068 0.12 0.03 2.74 0.12 0.22 remainder
4.00 0.15 0.29 2.21 Powder compacting No. 73 Example 17.49 13.21
0.69 0.054 0.03 0.12 2.15 0.79 0.41 remainder 0.25 0.15 0.22 2.78
Powder compacting No. 74 Example 16.88 14.15 0.77 0.024 0.24 0.09
2.23 0.28 0.48 remainder 2.67 0.33 0.43 13.75 Powder compacting No.
75 Example 17.32 12.65 0.48 0.021 0.08 0.26 2.81 0.17 0.29
remainder 0.31 0.34 0.71 16.19 Powder compacting No. 76 Example
17.25 12.87 0.35 0.065 0.09 0.05 2.15 0.35 0.62 remainder 1.80 0.14
0.40 2.15 Powder compacting No. 77 Example 17.66 12.55 0.96 0.017
0.07 0.07 2.24 0.05 0.25 remainder 1.00 0.14 0.15 8.24 Powder
compacting No. 78 Example 16.87 12.91 1.12 0.025 0.15 0.19 2.13
0.05 0.25 remainder 0.79 0.34 0.30 13.60 Powder compacting No. 79
Example 16.78 12.19 0.54 0.019 0.36 0.42 2.25 0.07 0.58 remainder
0.86 0.78 1.44 41.05 Powder compacting No. 80 Compar- 16.34 12.84
0.75 0.025 0.00 0.07 2.36 0.11 0.29 remainder 0.00 0.07 0.09 2.80
Powder ative compacting Example No. 81 Compar- 17.22 13.32 0.79
0.032 0.05 0.00 2.28 0.09 0.31 remainder -- 0.05 0.06 1.56 Powder
ative compacting Example No. 82 Compar- 16.75 14.23 0.75 0.015 0.00
0.00 2.33 0.12 0.33 remainder -- 0.00 0.00 0.00 Powder ative
compacting Example No. 83 Compar- 16.43 12.45 0.88 0.021 0.68 0.07
2.58 0.11 0.38 remainder 9.71 0.75 0.85 35.71 Powder ative
compacting Example No. 84 Compar- 16.35 13.04 0.66 0.035 0.06 0.71
2.36 0.05 0.41 remainder 0.08 0.77 1.17 22.00 Powder ative
compacting Example No. 85 Compar- 16.34 12.84 0.75 0.025 0.00 0.07
2.36 0.11 0.29 remainder -- 0.07 0.09 2.80 HIP ative treatment
Example
[0321] In Table 4, among the metal powders for powder metallurgy
and the sintered bodies of the respective sample Nos., those
corresponding to the invention are indicated by "Example", and
those not corresponding to the invention are indicated by
"Comparative Example".
[0322] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 4 is omitted.
Sample Nos. 86 to 101
[0323] Sintered bodies were obtained in the same manner as in the
case of sample No. 1 except that the composition and the like of
the metal powder for powder metallurgy were changed as shown in
Table 5, respectively.
TABLE-US-00005 TABLE 5 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Zr) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 86 Example 3.98 0.08 0.69 1.437 0.07 0.07 4.97 0.00
0.19 remainder 1.00 0.14 0.20 0.10 W; 6.10 Co: 8.46 No. 87 Example
4.11 0.11 0.74 1.423 0.11 0.04 4.88 0.00 0.28 remainder 2.75 0.15
0.20 0.11 W: 5.86 Co: 8.31 No. 88 Example 4.03 0.05 0.63 1.479 0.05
0.12 5.09 0.00 0.25 remainder 0.42 0.17 0.27 0.11 W: 6.31 Co: 8.07
No. 89 Compar- 4.11 0.06 0.79 1.426 0.05 0.00 5.11 0.00 0.23
remainder -- 0.05 0.06 0.04 W: 6.08 ative Co: 8.58 Example No. 90
Example 1.06 0.02 0.73 0.724 0.08 0.08 0.19 0.78 0.25 remainder
1.00 0.16 0.22 0.22 No. 91 Example 0.98 0.02 0.74 0.698 0.11 0.04
0.16 0.81 0.26 remainder 2.75 0.15 0.20 0.21 No. 92 Example 1.04
0.03 0.82 0.711 0.05 0.12 0.21 0.63 0.24 remainder 0.42 0.17 0.21
0.24 Al: 0.02 No. 93 Compar- 0.99 0.19 0.79 0.711 0.16 0.00 0.27
0.88 0.35 remainder -- 0.16 0.20 0.23 Al: 0.06 ative Example No. 94
Example 12.88 0.07 0.73 0.900 0.07 0.07 0.00 0.10 0.27 remainder
1.00 0.14 0.19 0.16 No. 95 Example 13.37 0.10 0.64 0.850 0.10 0.05
0.00 0.08 0.25 remainder 2.00 0.51 0.23 0.18 No. 96 Example 12.54
0.06 0.75 0.980 0.05 0.10 0.00 0.11 0.29 remainder 0.50 0.15 0.20
0.15 No. 97 Compar- 12.95 0.10 0.78 0.760 0.04 0.00 0.00 0.08 0.31
remainder -- 0.04 0.05 0.05 ative Example No. 98 Example 16.43 4.12
0.73 0.018 0.09 0.32 0.00 0.00 0.28 remainder 0.28 0.41 0.56 22.78
Cu: 3.98 No. 99 Example 16.19 3.89 0.36 0.052 0.05 0.29 0.00 0.00
0.25 remainder 0.17 0.34 0.94 6.54 Cu: 4.56 No. 100 Example 16.88
4.05 1.63 0.069 0.12 0.18 0.00 0.00 0.36 remainder 0.67 0.30 0.18
4.35 Cu: 4.78 No. 101 Compar- 17.18 3.54 0.62 0.024 0.05 0.00 0.00
0.00 0.32 remainder -- 0.05 0.28 2.08 Cu: 4.31 ative Example
[0324] In Table 5, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0325] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 5 is omitted.
2. Evaluation of Metal Powder (Zr--Nb Based)
[0326] With respect to the particle of the metal powder for powder
metallurgy of sample No. 1 corresponding to Example, an analysis in
the depth direction by Auger electron spectroscopy in combination
with sputtering was performed.
[0327] Then, the time of execution of sputtering was converted into
a depth from the surface of the particle (sputter depth) and shown
on the horizontal axis, and also the content of an atom (atomic
concentration) determined by the Auger electron spectroscopy was
shown on the vertical axis, and the analytical results were
plotted, whereby Auger electron spectra were obtained.
[0328] The Auger electron spectra obtained from the particle of the
metal powder for powder metallurgy of sample No. 1 are shown in
FIG. 3. The four horizontal straight lines drawn overlapping the
spectra indicate the contents of Fe, Cr, Si, and O in the whole
particle of sample No. 1, respectively.
[0329] As apparent from FIG. 3, in the particle of sample No. 1,
the content of Cr little fluctuates in a region from the surface
(at a depth of 0 nm) to a depth of 60 nm. Accordingly, it is
confirmed that the content of Cr on the surface of the particle
(Cr(0)) falls within the range of 70% or more and 170% or less the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0330] Further, it is also confirmed that the content of Cr on the
surface of the particle (Cr(0)) falls within the range of 0.2% by
atom or more and 15% by atom or less.
[0331] On the other hand, also with respect to the particle of the
metal powder for powder metallurgy of sample No. 23 corresponding
to Comparative Example, an analysis in the depth direction by Auger
electron spectroscopy in combination with sputtering was performed
in the same manner.
[0332] The Auger electron spectra obtained from the particle of the
metal powder for powder metallurgy of sample No. 23 are shown in
FIG. 4. The four horizontal straight lines drawn overlapping the
spectra indicate the contents of Fe, Cr, Si, and O in the whole
particle of sample No. 23, respectively.
[0333] As apparent from FIG. 4, it is confirmed that in the
particle of sample No. 23, the content of Cr relatively largely
fluctuates in a region from the surface to a depth of 60 nm.
[0334] Further, it is confirmed that the content of Cr on the
surface of the particle (Cr(0)) exceeds 15% by atom.
[0335] Incidentally, also with respect to the particles of sample
Nos. other than sample No. 1 and sample No. 23, the content of Cr
was determined in the same manner.
[0336] The determined contents are shown in Tables 6 and 10.
[0337] Further, with respect to the particles of the respective
sample Nos., the content of Si on the surface of the particle
(Si(0)), the content of Si at a depth of 60 nm from the surface of
the particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0338] The determined contents are shown in Tables 6 and 10.
3. Evaluation of Sintered Body (Zr--Nb Based)
3.1 Evaluation of Relative Density
[0339] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 1 to 5, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0340] The calculation results are shown in Tables 6 to 10.
3.2 Evaluation of Vickers Hardness
[0341] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 1 to 4, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0342] The measurement results are shown in Tables 6 to 9.
3.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0343] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 1 to 4, the tensile strength, 0.2% proof
stress, and elongation were measured in accordance with the metal
material tensile test method specified in JIS Z 2241 (2011).
[0344] Then, the measured values of these physical properties were
evaluated according to the following evaluation criteria.
Evaluation Criteria for Tensile Strength (Tables 6 and 9)
[0345] A: The tensile strength of the sintered body is 520 MPa or
more.
[0346] B: The tensile strength of the sintered body is 510 MPa or
more and less than 520 MPa.
[0347] C: The tensile strength of the sintered body is 500 MPa or
more and less than 510 MPa.
[0348] D: The tensile strength of the sintered body is 490 MPa or
more and less than 500 MPa.
[0349] E: The tensile strength of the sintered body is 480 MPa or
more and less than 490 MPa.
[0350] F: The tensile strength of the sintered body is less than
480 MPa.
Evaluation Criteria for Tensile Strength (Tables 7 and 8)
[0351] A: The tensile strength of the sintered body is 560 MPa or
more.
[0352] B: The tensile strength of the sintered body is 550 MPa or
more and less than 560 MPa.
[0353] C: The tensile strength of the sintered body is 540 MPa or
more and less than 550 MPa.
[0354] D: The tensile strength of the sintered body is 530 MPa or
more and less than 540 MPa.
[0355] E: The tensile strength of the sintered body is 520 MPa or
more and less than 530 MPa.
[0356] F: The tensile strength of the sintered body is less than
520 MPa.
Evaluation Criteria for 0.2% Proof Stress (Tables 6 and 9)
[0357] A: The 0.2% proof stress of the sintered body is 195 MPa or
more.
[0358] B: The 0.2% proof stress of the sintered body is 190 MPa or
more and less than 195 MPa.
[0359] C: The 0.2% proof stress of the sintered body is 185 MPa or
more and less than 190 MPa.
[0360] D: The 0.2% proof stress of the sintered body is 180 MPa or
more and less than 185 MPa.
[0361] E: The 0.2% proof stress of the sintered body is 175 MPa or
more and less than 180 MPa.
[0362] F: The 0.2% proof stress of the sintered body is less than
175 MPa.
Evaluation Criteria for 0.2% Proof Stress (Tables 7 and 8)
[0363] A: The 0.2% proof stress of the sintered body is 225 MPa or
more.
[0364] B: The 0.2% proof stress of the sintered body is 220 MPa or
more and less than 225 MPa.
[0365] C: The 0.2% proof stress of the sintered body is 215 MPa or
more and less than 220 MPa.
[0366] D: The 0.2% proof stress of the sintered body is 210 MPa or
more and less than 215 MPa.
[0367] E: The 0.2% proof stress of the sintered body is 205 MPa or
more and less than 210 MPa.
[0368] F: The 0.2% proof stress of the sintered body is less than
205 MPa.
Evaluation Criteria for Elongation
[0369] A: The elongation of the sintered body is 48% or more.
[0370] B: The elongation of the sintered body is 46% or more and
less than 48%.
[0371] C: The elongation of the sintered body is 44% or more and
less than 46%.
[0372] D: The elongation of the sintered body is 42% or more and
less than 44%.
[0373] E: The elongation of the sintered body is 40% or more and
less than 42%.
[0374] F: The elongation of the sintered body is less than 40%.
[0375] The above evaluation results are shown in Tables 6 to 9. As
described above, the evaluation criteria are different between
Tables 6 and 9 and Tables 7 and 8 depending on the values of the
physical properties.
3.4 Evaluation of Fatigue Strength
[0376] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 1 to 4, the fatigue strength was measured.
[0377] The fatigue strength was measured in accordance with the
test method specified in JIS Z 2273 (1978). The waveform of an
applied load corresponding to a repeated stress was set to an
alternating sine wave, and the minimum/maximum stress ratio
(minimum stress/maximum stress) was set to 0.1. Further, the
repeated frequency was set to 30 Hz, and the repeat count was set
to 1.times.10.sup.7.
[0378] Then, the measured fatigue strength was evaluated according
to the following evaluation criteria.
Evaluation Criteria for Fatigue Strength
[0379] A: The fatigue strength of the sintered body is 260 MPa or
more.
[0380] B: The fatigue strength of the sintered body is 240 MPa or
more and less than 260 MPa.
[0381] C: The fatigue strength of the sintered body is 220 MPa or
more and less than 240 MPa.
[0382] D: The fatigue strength of the sintered body is 200 MPa or
more and less than 220 MPa.
[0383] E: The fatigue strength of the sintered body is 180 MPa or
more and less than 200 MPa.
[0384] F: The fatigue strength of the sintered body is less than
180 MPa.
[0385] The above evaluation results are shown in Tables 6 to 9.
TABLE-US-00006 TABLE 6 Metal powder Average particle Cr(0)/ Si(0)/
O(0)/ Sample diameter Cr(0) Cr(60) Cr(60) Si(0) Si(60) Si(60) O(0)
Si(0) No. -- .mu.m at % at % % at % at % % at % -- No. 1 Example
4.05 9.9 7.2 137.5 36.5 18.3 199.5 8.2 0.22 No. 2 Example 3.79 6.7
8.5 78.8 41.3 16.8 245.8 9.8 0.24 No. 3 Example 3.84 12.4 7.7 161.0
28.6 6.7 426.9 7.2 0.25 No. 4 Example 3.92 -- -- -- -- -- -- -- --
No. 5 Example 4.56 -- -- -- -- -- -- -- -- No. 6 Example 3.68 -- --
-- -- -- -- -- -- No. 7 Example 3.77 -- -- -- -- -- -- -- -- No. 8
Example 3.81 -- -- -- -- -- -- -- -- No. 9 Example 3.85 -- -- -- --
-- -- -- -- No. 10 Example 4.23 -- -- -- -- -- -- -- -- No. 11
Example 3.21 -- -- -- -- -- -- -- -- No. 12 Example 3.36 -- -- --
-- -- -- -- -- No. 13 Example 6.18 -- -- -- -- -- -- -- -- No. 14
Example 10.8 -- -- -- -- -- -- -- -- No. 15 Example 15.4 -- -- --
-- -- -- -- -- No. 16 Example 5.23 -- -- -- -- -- -- -- -- No. 17
Example 4.42 -- -- -- -- -- -- -- -- No. 18 Example 8.11 -- -- --
-- -- -- -- -- No. 19 Example 7.65 -- -- -- -- -- -- -- -- No. 20
Example 7.25 -- -- -- -- -- -- -- -- No. 21 Compar- 3.77 20.4 9.5
214.7 22.6 15.2 148.7 10.1 0.45 ative Example No. 22 Compar- 3.94
19.3 10.1 191.1 19.8 12.4 159.7 12.8 0.65 ative Example No. 23
Compar- 3.65 18.5 10.8 171.3 24.8 16.5 150.3 11.0 0.44 ative
Example No. 24 Compar- 4.87 -- -- -- -- -- -- -- -- ative Example
No. 25 Compar- 4.25 -- -- -- -- -- -- -- -- ative Example No. 26
Compar- 3.64 -- -- -- -- -- -- -- -- ative Example No. 27 Compar-
3.55 -- -- -- -- -- -- -- -- ative Example No. 28 Compar- 4.87 --
-- -- -- -- -- -- -- ative Example No. 29 Compar- 4.66 -- -- -- --
-- -- -- -- ative Example No. 30 Compar- 3.77 -- -- -- -- -- -- --
-- ative Example Evaluation results of sintered body 0.2% Relative
Vickers Tensile proof Elonga- Fatigue Sample density hardness
strength stress tion strength No. -- % -- -- -- -- -- No. 1 Example
99.5 165 A A A A No. 2 Example 99.6 175 A A A A No. 3 Example 99.3
171 A A A A No. 4 Example 98.8 153 B A A A No. 5 Example 99.7 182 A
A A A No. 6 Example 98.7 154 B B A B No. 7 Example 98.8 156 B B A B
No. 8 Example 98.3 149 B B A B No. 9 Example 98.1 148 B B B B No.
10 Example 98.5 152 B B A B No. 11 Example 98.1 146 B B B B No. 12
Example 97.8 144 B B C B No. 13 Example 97.6 142 C C C C No. 14
Example 97.5 144 B C C C No. 15 Example 97.2 141 C C C C No. 16
Example 97.8 141 B B B B No. 17 Example 97.3 163 B B C B No. 18
Example 99.3 161 A A A A No. 19 Example 99.4 171 A A A A No. 20
Example 99.1 164 A A A A No. 21 Compar- 96.4 128 D D B D ative
Example No. 22 Compar- 96.8 134 D D B D ative Example No. 23
Compar- 96.2 123 E E C E ative Example No. 24 Compar- 94.7 115 D D
D D ative Example No. 25 Compar- 94.6 118 D D E D ative Example No.
26 Compar- 94.5 102 E E C E ative Example No. 27 Compar- 92.6 135 F
F E F ative Example No. 28 Compar- 95.3 118 D D B D ative Example
No. 29 Compar- 93.2 138 E E F E ative Example No. 30 Compar- 99.2
175 A A B A ative Example
TABLE-US-00007 TABLE 7 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Fatigue Sample diameter density hardness strength stress tion
strength No. -- .mu.m % -- -- -- -- -- No. 31 Example 5.68 99.3 178
A A A A No. 32 Example 4.79 99.5 185 A A A A No. 33 Example 4.05
98.6 167 B B A B No. 34 Example 3.81 98.8 158 B B A B No. 35
Example 3.05 98.2 162 B B B B No. 36 Example 4.25 97.6 154 B B C B
No. 37 Example 9.86 97.8 158 B B B B No. 38 Example 14.2 97.5 154 B
C C C No. 39 Example 2.56 98.6 171 B B A A No. 40 Example 14.2 98.3
173 B B A A No. 41 Example 11.53 99.1 174 A A A A No. 42 Example
9.64 99.2 180 A A A A No. 43 Example 8.25 98.3 163 B B A B No. 44
Compar- 5.32 96.4 127 D D B D ative Example No. 45 Compar- 5.48
96.7 136 D D B D ative Example No. 46 Compar- 4.23 95.2 121 D D D D
ative Example No. 47 Compar- 4.51 94.8 105 E E F E ative Example
No. 48 Compar- 5.32 99.2 174 A A B A ative Example
TABLE-US-00008 TABLE 8 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Fatigue Sample diameter density hardness strength stress tion
strength No. -- .mu.m % -- -- -- -- -- No. 49 Example 3.97 99.6 172
A A A A No. 50 Example 3.25 99.3 167 A A B A No. 51 Example 6.54
98.4 142 A A B A No. 52 Example 5.48 98.2 157 B B B B No. 53
Example 3.92 98.4 161 B B B B No. 54 Example 3.74 97.3 148 B B C B
No. 55 Example 16.45 97.1 137 C C C C No. 56 Example 22.1 97.0 135
c C C C No. 57 Example 10.05 97.5 138 B B B B No. 58 Example 7.23
98.8 165 B B A B No. 59 Example 8.12 99.3 165 A A A A No. 60
Example 7.22 99.0 160 A A B A No. 61 Example 13.65 98.2 134 A A B A
No. 62 Compar- 3.89 96.3 127 D D B D ative Example No. 63 Compar-
3.47 96.7 136 D D B D ative Example No. 64 Compar- 4.25 94.7 116 D
D D D ative Example No. 65 Compar- 3.64 95.2 119 D D E D ative
Example No. 66 Compar- 3.89 99.4 170 A A B A ative Example
TABLE-US-00009 TABLE 9 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Fatigue Sample diameter density hardness strength stress tion
strength No. -- .mu.m % -- -- -- -- -- No. 67 Example 4.05 99.6 168
A A A A No. 68 Example 3.79 99.6 177 A A A A No. 69 Example 3.84
99.4 172 A A A A No. 70 Example 3.92 98.9 155 B A A A No. 71
Example 4.56 99.7 183 A A A A No. 72 Example 3.68 98.9 158 B B A B
No. 73 Example 3.77 99.0 162 B B A B No. 74 Example 3.81 98.5 155 B
B A B No. 75 Example 3.85 98.4 156 B B B B No. 76 Example 4.23 98.7
157 B B A B No. 77 Example 3.21 98.4 159 B B B B No. 78 Example
3.36 98.1 150 B B C B No. 79 Example 6.18 97.9 146 C C C C No. 80
Compar- 3.77 96.6 129 D D B D ative Example No. 81 Compar- 3.94
96.9 136 D D B D ative Example No. 82 Compar- 3.65 96.4 128 E E C E
ative Example No. 83 Compar- 4.87 94.9 119 D D D D ative Example
No. 84 Compar- 4.25 94.8 125 D D E D ative Example No. 85 Compar-
3.77 99.3 180 A A B A ative Example
TABLE-US-00010 TABLE 10 Metal powder Average particle Cr(0)/ Si(0)/
O(0)/ Sample diameter Cr(0) Cr(60) Cr(60) Si(0) Si(60) Si(60) O(0)
Si(0) No. -- .mu.m at % at % % at % at % % at % -- No. 86 Example
4.32 2.4 2.1 114.3 42.3 15.4 274.7 7.8 0.18 No. 87 Example 4.31 3.2
2.4 133.3 39.8 16.3 244.2 8.2 0.21 No. 88 Example 7.32 2.8 2.3
121.7 36.8 13.1 280.9 9.2 0.25 No. 89 Compar- 4.12 4.5 2.1 214.3
18.4 9.8 187.8 14.5 0.79 ative Example No. 90 Example 6.19 1.2 0.8
15.0 44.5 19.5 228.2 6.8 0.15 No. 91 Example 4.45 0.9 1.0 90.0 48.2
22.1 218.1 9.4 0.20 No. 92 Example 7.29 1.0 0.9 111.1 45.3 18.7
242.2 8.5 0.19 No. 93 Compar- 4.18 0.7 1.1 63.6 21.5 17.2 125.0
12.6 0.59 ative Example No. 94 Example 3.86 5.6 4.5 124.4 38.5 18.2
211.5 7.8 0.20 No. 95 Example 3.92 7.2 6.5 110.8 39.7 19.4 204.6
6.8 0.17 No. 96 Example 4.02 6.8 6.9 98.6 40.2 15.9 252.8 5.9 0.15
No. 97 Compar- 3.48 9.5 5.4 175.9 25.6 16.9 151.5 13.1 0.51 ative
Example No. 98 Example 4.05 9.1 7.3 124.7 36.7 18.3 200.5 8.1 0.22
No. 99 Example 9.85 9.3 7.5 124.0 37.1 16.4 226.2 7.9 0.21 No. 100
Example 8.42 8.7 8.9 97.8 35.4 15.9 222.6 7.5 0.21 No. 101 Compar-
4.02 12.5 7.1 176.1 28.1 18.5 151.9 13.6 0.48 ative Example
Evaluation results of sintered body 0.2% Relative Vickers Tensile
proof Elonga- Relative Sample density hardness strength stress tion
density No. -- % -- -- -- -- -- No. 86 Example 99.7 -- -- -- -- --
No. 87 Example 98.6 -- -- -- -- -- No. 88 Example 98.7 -- -- -- --
-- No. 89 Compar- 97.6 -- -- -- -- -- ative Example No. 90 Example
98.7 -- -- -- -- -- No. 91 Example 98.3 -- -- -- -- -- No. 92
Example 98.1 -- -- -- -- -- No. 93 Compar- 96.9 -- -- -- -- --
ative Example No. 94 Example 99.5 -- -- -- -- -- No. 95 Example
99.3 -- -- -- -- -- No. 96 Example 99.4 -- -- -- -- -- No. 97
Compar- 94.5 -- -- -- -- -- ative Example No. 98 Example 99.5 -- --
-- -- -- No. 99 Example 98.7 -- -- -- -- -- No. 100 Example 98.6 --
-- -- -- -- No. 101 Compar- 96.6 -- -- -- -- -- ative Example
[0386] As apparent from Tables 6 to 10, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example (excluding the sintered bodies having undergone
the HIP treatment). Further, it was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, elongation, and fatigue strength between the sintered
bodies corresponding to Example and the sintered bodies
corresponding to Comparative Example (excluding the sintered bodies
having undergone the HIP treatment).
[0387] On the other hand, by comparison of the values of the
respective physical properties between the sintered bodies
corresponding to Example and the sintered bodies having undergone
the HIP treatment, it was confirmed that the values of the physical
properties are all comparable to each other.
4. Production of Sintered Body (Hf--Nb Based)
Sample Nos. 102 to 145
[0388] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Tables 11 to 14,
respectively.
TABLE-US-00011 TABLE 11 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Hf) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 102 Example 16.25 12.56 0.71 0.02 0.09 0.05 2.09 0.05
0.25 remainder 1.80 0.14 0.20 8.24 No. 103 Example 17.14 12.54 0.57
0.02 0.07 0.05 2.45 0.09 0.32 remainder 1.40 0.12 0.21 5.45 No. 104
Example 17.78 13.25 0.53 0.03 0.07 0.08 2.06 0.08 0.41 remainder
0.88 0.15 0.28 5.56 No. 105 Example 16.25 14.68 0.82 0.01 0.06 0.03
2.89 0.08 0.25 remainder 2.00 0.09 0.11 7.50 No. 106 Example 17.52
13.87 0.74 0.03 0.09 0.10 2.63 0.11 0.34 remainder 0.90 0.19 1.26
7.31 No. 107 Example 16.82 12.03 0.53 0.07 0.11 0.04 2.76 0.11 0.23
remainder 2.75 0.15 0.28 2.17 No. 108 Example 17.52 13.25 0.68 0.06
0.07 0.12 2.21 0.78 0.41 remainder 0.58 0.19 0.28 3.45 No. 109
Example 16.34 12.84 0.75 0.03 0.00 0.07 2.36 0.11 0.29 remainder
0.00 0.07 0.09 2.80 No. 110 Compar- 17.25 13.35 0.82 0.03 0.08 0.00
2.23 0.09 0.32 remainder -- 0.08 0.10 2.86 ative Example No. 111
Compar- 16.75 14.23 0.75 0.02 0.00 0.00 2.33 0.12 0.33 remainder --
0.00 0.00 0.00 ative Example No. 112 Compar- 16.34 12.54 0.87 0.02
0.71 0.05 2.56 0.11 0.36 remainder 14.20 0.76 0.87 36.19 ative
Example No. 113 Compar- 16.44 13.12 0.65 0.03 0.04 0.68 2.41 0.06
0.42 remainder 0.06 0.72 1.11 21.18 ative Example No. 114 Compar-
17.63 13.21 0.14 0.01 0.06 0.07 2.77 0.11 0.27 remainder 0.86 0.13
0.93 10.83 ative Example No. 115 Compar- 17.54 13.33 1.91 0.05 0.07
0.05 2.68 0.34 0.48 remainder 1.40 0.12 0.06 2.22 ative Example
TABLE-US-00012 TABLE 12 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Hf) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 116 Example 18.96 13.54 0.82 0.041 0.09 0.05 3.55 0.35
0.41 remainder 1.80 0.14 0.17 3.41 No. 117 Example 18.25 14.86 0.54
0.021 0.06 0.09 3.12 0.87 0.39 remainder 0.67 0.15 0.28 7.14 No.
118 Example 19.74 11.32 0.34 0.067 0.09 0.09 3.88 0.45 0.55
remainder 1.00 0.18 0.53 2.69 No. 119 Compar- 18.67 11.36 0.78
0.053 0.00 0.07 3.47 0.22 0.29 remainder 0.00 0.07 0.09 1.32 ative
Example No. 120 Compar- 19.54 14.35 0.89 0.022 0.11 0.00 3.75 0.09
0.31 remainder -- 0.11 0.12 5.00 ative Example No. 121 Compar-
18.69 11.87 0.71 0.027 0.54 0.07 3.76 0.12 0.38 remainder 7.71 0.61
0.86 22.59 ative Example No. 122 Compar- 19.42 14.58 0.62 0.024
0.06 0.66 3.54 0.07 0.41 remainder 0.09 0.72 1.16 30.00 ative
Example
TABLE-US-00013 TABLE 13 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Hf) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 123 Example 19.21 8.25 0.67 0.035 0.08 0.05 0.00 0.18
0.25 remainder 1.60 0.13 0.19 3.71 No. 124 Example 19.74 8.62 0.89
0.039 0.06 0.09 0.05 0.08 0.29 remainder 0.67 0.15 0.17 3.85 No.
125 Example 18.30 10.31 0.43 0.017 0.14 0.09 0.03 0.23 0.41
remainder 1.56 0.23 0.53 13.53 No. 126 Compar- 19.11 8.23 0.77
0.055 0.00 0.06 0.00 0.14 0.25 remainder 0.00 0.06 0.08 1.09 ative
Example No. 127 Compar- 18.78 9.45 0.76 0.024 0.07 0.00 0.02 0.11
0.29 remainder -- 0.07 0.09 2.92 ative Example No. 128 Compar-
18.42 8.36 0.38 0.011 0.54 0.08 0.03 0.25 0.28 remainder 6.75 0.62
1.63 56.36 ative Example No. 129 Compar- 19.21 8.45 0.45 0.018 0.06
0.58 0.04 0.16 0.32 remainder 0.10 0.64 1.42 35.56 ative
Example
TABLE-US-00014 TABLE 14 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Hf) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 130 Example 3.92 0.07 0.71 1.425 0.10 0.05 5.06 0.00
0.18 remainder 2.00 0.15 0.21 0.11 W: 6.07 Co: 8.47 No. 131 Example
4.32 0.21 0.83 1.395 0.05 0.06 4.75 0.00 0.27 remainder 0.83 0.11
0.13 0.08 W: 6.56 Co: 8.14 No. 132 Example 4.12 0.13 0.76 1.425
0.15 0.05 4.87 0.00 0.27 remainder 3.00 0.20 0.26 0.14 W: 5.87 Co:
8.26 No. 133 Compar- 4.11 0.06 0.79 1.426 0.06 0.00 5.11 0.00 0.23
remainder -- 0.06 1.08 0.04 W: 6.08 ative Co: 8.58 Example No. 134
Example 1.08 0.03 0.75 0.712 0.14 0.08 0.23 0.72 0.24 remainder
1.75 0.22 1.29 0.31 No. 135 Example 0.92 0.00 0.86 0.707 0.21 0.06
0.23 0.77 0.23 remainder 3.50 0.27 0.31 0.38 No. 136 Example 1.06
0.08 0.80 0.725 0.04 0.05 0.28 0.68 0.21 remainder 0.80 0.09 0.11
0.12 Al: 0.03 No. 137 Compar- 0.97 0.15 0.77 0.704 0.18 0.00 0.28
0.85 0.34 remainder -- 0.18 0.23 0.26 Al: 0.06 ative Example No.
138 Example 12.85 0.08 0.72 0.910 0.09 0.05 0.00 0.11 0.29
remainder 1.80 0.14 0.19 0.15 No. 139 Example 13.42 0.11 0.65 0.840
0.11 0.06 0.00 0.08 0.24 remainder 1.83 0.17 0.26 0.20 No. 140
Example 12.55 0.07 0.75 0.960 0.06 0.08 0.00 0.11 0.31 remainder
0.75 0.14 0.19 0.15 No. 141 Compar- 12.97 0.11 0.76 0.750 0.06 0.00
0.00 0.09 0.32 remainder -- 0.06 0.08 0.08 ative Example No. 142
Example 16.45 4.18 0.75 0.019 0.13 0.32 0.00 0.00 0.29 remainder
0.41 0.45 0.60 23.68 Cu: 3.89 No. 143 Example 16.17 3.87 0.39 0.045
0.07 0.28 0.00 0.00 0.24 remainder 0.25 0.35 0.90 7.78 Cu: 4.54 No.
144 Example 16.87 4.03 1.58 0.067 0.16 0.18 0.00 0.00 0.35
remainder 0.89 0.34 0.22 5.07 Cu: 4.75 No. 145 Compar- 17.22 3.56
0.64 0.025 0.09 0.00 0.00 0.00 0.33 remainder -- 0.09 1.14 3.60 Cu:
4.33 ative Example
[0389] In Tables 11 to 14, among the sintered bodies of the
respective sample Nos., those corresponding to the invention are
indicated by "Example", and those not corresponding to the
invention are indicated by "Comparative Example".
[0390] Each sintered body contained very small amounts of
impurities, but the description thereof in Tables 11 to 14 is
omitted.
5. Evaluation of Metal Powder (Hf--Nb Based)
[0391] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0392] The determined contents are shown in Tables 15 and 18.
[0393] As apparent from Tables 15 and 18, it is confirmed that in
the particles of the metal powders corresponding to Example, the
content of Cr on the surface (Cr(0)) falls within the range of 70%
or more and 170% or less the content of Cr at a depth of 60 nm from
the surface of the particle (Cr(60)).
[0394] Further, it is also confirmed that the content of Cr on the
surface of the particle 1 (Cr(0)) falls within the range of 0.2% by
atom or more and 15% by atom or less.
6. Evaluation of Sintered Body (Hf--Nb Based)
6.1 Evaluation of Relative Density
[0395] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 11 to 14, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0396] The calculation results are shown in Tables 15 to 18.
6.2 Evaluation of Vickers Hardness
[0397] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 11 to 14, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0398] The measurement results are shown in Tables 15 to 18.
6.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0399] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 11 to 13, the tensile strength, 0.2% proof
stress, and elongation were measured in accordance with the metal
material tensile test method specified in JIS Z 2241 (2011).
[0400] Then, the values of the physical properties of the sintered
bodies of the respective sample Nos. shown in Table 11 were
evaluated according to the above-mentioned evaluation criteria
applied to the Tables 6 and 9, and the values of the physical
properties of the sintered bodies of the respective sample Nos.
shown in Tables 12 and 13 were evaluated according to the
above-mentioned evaluation criteria applied to the Tables 7 and
8.
[0401] The above evaluation results are shown in Tables 15 to
17.
TABLE-US-00015 TABLE 15 Metal powder Evaluation results of sintered
body Average 0.2% particle Cr(0)/ Si(0)/ O(0)/ Relative Vickers
Tensile proof Elonga- Sample diameter Cr(0) Cr(60) Cr(60) Si(0)
Si(60) Si(60) O(0) Si(0) density hardness strength stress tion No.
-- .mu.m at % at % % at % at % % at % -- % -- -- -- -- No. 102
Example 4.12 9.7 7.5 129.3 35.8 18.1 197.8 8.5 0.24 99.5 162 A A A
No. 103 Example 4.25 6.9 8.7 79.3 40.8 17.2 237.2 9.7 0.24 99.3 173
A A A No. 104 Example 4.02 12.1 7.9 153.2 27.8 7.5 370.7 7.8 0.28
98.7 160 A A A No. 105 Example 3.88 -- -- -- -- -- -- -- -- 98.5
153 B A A No. 106 Example 4.56 -- -- -- -- -- -- -- -- 98.9 175 A A
A No. 107 Example 3.98 -- -- -- -- -- -- -- -- 99.2 170 A A A No.
108 Example 3.77 -- -- -- -- -- -- -- -- 98.2 185 B B B No. 109
Compar- 3.86 21.2 10.1 209.9 21.8 15.4 141.6 10.3 0.47 96.4 185 D D
B ative Example No. 110 Compar- 3.95 19.7 10.5 187.6 20.1 13.4
150.0 13.2 0.66 96.8 180 D D B ative Example No. 111 Compar- 4.05
18.7 9.4 198.9 24.6 17.8 138.2 11.4 0.46 96.2 192 E E C ative
Example No. 112 Compar- 4.57 -- -- -- -- -- -- -- -- 94.7 202 D D D
ative Example No. 113 Compar- 4.52 -- -- -- -- -- -- -- -- 94.6 211
D D E ative Example No. 114 Compar- 3.65 -- -- -- -- -- -- -- --
94.6 195 E E D ative Example No. 115 Compar- 3.28 -- -- -- -- -- --
-- -- 93.4 214 F F E ative Example
TABLE-US-00016 TABLE 16 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 116 Example 5.86 99.1 167 A A A No. 117 Example
4.97 98.9 170 A A A No. 118 Example 4.25 98.6 184 B B B No. 119
Compar- 5.31 96.3 195 D D B ative Example No. 120 Compar- 5.83 96.6
189 D D B ative Example No. 121 Compar- 4.52 95.1 201 D D D ative
Example No. 122 Compar- 4.12 94.9 205 E E F ative Example
TABLE-US-00017 TABLE 17 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 123 Example 4.08 99.3 164 A A A No. 124 Example
3.58 99.0 175 A A A No. 125 Example 6.41 98.5 182 A A B No. 126
Compar- 3.98 96.3 195 D D B ative Example No. 127 Compar- 3.58 96.7
192 D D B ative Example No. 128 Compar- 4.35 94.7 205 D D E ative
Example No. 129 Compar- 4.56 95.2 201 D D E ative Example
TABLE-US-00018 TABLE 18 Metal powder Evaluation results of sintered
body Average 0.2% particle Cr(0)/ Si(0)/ O(0)/ Relative Vickers
Tensile proof Elonga- Sample diameter Cr(0) Cr(60) Cr(6) Si(0)
Si(60) Si(60) O(0) Si(0) density hardness strength stress tion No.
-- .mu.m at % at % % at % at % % at % -- % -- -- -- -- No. 130
Example 4.25 2.3 2.1 109.5 40.5 16.8 241.1 7.9 0.20 99.5 -- -- --
-- No. 131 Example 5.34 3.1 2.5 124.0 38.7 16.4 236.0 8.3 0.21 99.0
-- -- -- -- No. 132 Example 4.28 2.9 2.4 120.8 36.9 13.4 275.4 9.2
0.25 98.5 -- -- -- -- No. 133 Compar- 3.97 4.3 2.2 195.5 18.2 8.7
209.2 13.6 0.75 97.5 -- -- -- -- ative Example No. 134 Example 6.25
1.1 0.8 137.5 43.2 19.2 225.0 6.7 0.16 98.9 -- -- -- -- No. 135
Example 6.87 1 1 100.0 44.6 20.4 218.6 9.2 0.21 98.8 -- -- -- --
No. 136 Example 14.36 1.2 0.9 133.3 43.8 17.3 253.2 8.4 0.19 98.4
-- -- -- -- No. 137 Compar- 4.35 0.8 1.2 66.7 22.1 16.5 133.9 12.5
0.57 96.8 -- -- -- -- ative Example No. 138 Example 4.12 5.8 4.6
126.1 38.4 18.5 207.6 7.5 0.20 99.4 -- -- -- -- No. 139 Example
5.92 7.4 6.3 117.5 39.3 20.1 195.5 6.5 0.17 99.4 -- -- -- -- No.
140 Example 7.02 6.9 7.2 95.8 39.7 16.2 245.1 5.7 0.14 99.2 -- --
-- -- No. 141 Compar- 4.56 10.1 5.7 177.2 26.1 20.1 129.9 13.3 0.51
94.8 -- -- -- -- ative Example No. 142 Example 4.12 9.5 7.4 128.4
36.5 18.3 199.5 8.5 0.23 99.5 -- -- -- -- No. 143 Example 10.03 9.1
7.6 119.7 36.1 16.8 214.9 9.8 0.27 98.8 -- -- -- -- No. 144 Example
8.57 8.8 8.5 103.5 33.5 15.8 212.0 9.1 0.27 98.7 -- -- -- -- No.
145 Compar- 3.96 12.9 6.5 198.5 27.4 19.2 142.7 13.8 0.50 96.7 --
-- -- -- ative Example
[0402] As apparent from Tables 15 to 18, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
7. Production of Sintered Body (Ti--Nb Based)
Sample Nos. 146 to 155
[0403] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 19, respectively.
Sample No. 156
[0404] A metal powder having an average particle diameter of 4.62
.mu.m, a Ti powder having an average particle diameter of 40 .mu.m,
and a Nb powder having an average particle diameter of 25 .mu.m
were mixed, whereby a mixed powder was prepared. In the preparation
of the mixed powder, each of the mixing amounts of the metal
powder, the Ti powder, and the Nb powder was adjusted so that the
composition of the mixed powder was as shown in Table 19.
[0405] Then, a sintered body was obtained in the same manner as the
method for producing the sintered body of sample No. 1 using this
mixed powder.
TABLE-US-00019 TABLE 19 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Ti) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 146 Example 16.52 12.54 0.77 0.015 0.08 0.07 2.13 0.06
0.25 remainder 1.14 0.15 0.19 10.00 No. 147 Example 16.86 13.15
0.51 0.021 0.08 0.08 2.21 0.51 0.42 remainder 1.00 0.16 0.31 7.62
No. 148 Example 16.63 11.87 0.81 0.025 0.06 0.10 2.07 0.35 0.24
remainder 0.60 0.16 0.20 6.40 No. 149 Example 17.12 12.61 0.98
0.065 0.04 0.18 2.23 0.07 0.54 remainder 0.22 0.22 0.22 3.38 No.
150 Example 16.23 13.54 0.51 0.009 0.04 0.08 2.26 0.02 0.35
remainder 0.50 0.12 0.24 13.33 No. 151 Example 17.85 12.35 0.42
0.125 0.09 0.08 2.57 0.35 0.25 remainder 1.13 0.17 0.40 1.36 No.
152 Compar- 16.87 11.42 0.56 0.056 0.00 0.08 2.47 0.12 0.25
remainder 0.00 0.08 0.14 1.43 ative Example No. 153 Compar- 17.56
14.51 0.78 0.032 0.12 0.00 2.68 0.11 0.33 remainder -- 0.12 0.15
3.75 ative Example No. 154 Compar- 16.78 11.24 0.87 0.012 0.54 0.06
2.55 0.15 0.32 remainder 9.00 0.60 0.69 50.00 ative Example No. 155
Compar- 17.65 14.15 0.68 0.053 0.08 0.89 2.63 0.06 0.25 remainder
0.09 0.97 1.43 18.30 ative Example No. 156 Compar- 16.88 14.10 0.87
0.056 0.45 0.20 2.25 0.08 0.26 remainder 2.25 0.65 0.75 11.61 Mixed
ative powder Example
[0406] In Table 19, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0407] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 19 is omitted.
8. Evaluation of Metal Powder (Ti--Nb Based)
[0408] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0409] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0410] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0411] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
9. Evaluation of Sintered Body (Ti--Nb Based)
9.1 Evaluation of Relative Density
[0412] With respect to the sintered bodies of the respective sample
Nos. shown in Table 19, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0413] The calculation results are shown in Table 20.
9.2 Evaluation of Vickers Hardness
[0414] With respect to the sintered bodies of the respective sample
Nos. shown in Table 19, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0415] The measurement results are shown in Table 20.
9.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0416] With respect to the sintered bodies of the respective sample
Nos. shown in Table 19, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0417] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to the Tables 6 and 9.
[0418] The above evaluation results are shown in Table 20.
TABLE-US-00020 TABLE 20 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 146 Example 4.34 97.9 179 A A A No. 147 Example
4.79 99.3 178 A A A No. 148 Example 4.05 99.4 175 A A A No. 149
Example 3.89 98.7 180 B B A No. 150 Example 4.12 98.5 185 B B B No.
151 Example 4.26 98.2 189 B B C No. 152 Compar- 4.31 96.5 191 D D B
ative Example No. 153 Compar- 4.48 96.6 189 D D B ative Example No.
154 Compar- 4.25 95.3 205 D D D ative Example No. 155 Compar- 4.36
94.7 215 E E F ative Example No. 156 Compar- 4.62 95.9 214 E E F
ative Example
[0419] As apparent from Table 20, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
10. Production of Sintered Body (Nb--Ta Based)
Sample Nos. 157 to 166
[0420] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 21, respectively.
TABLE-US-00021 TABLE 21 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Nb) (Ta) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 157 Example 16.21 12.15 0.63 0.035 0.07 0.12 2.21 0.06
0.38 remainder 0.58 0.19 0.30 5.43 No. 158 Example 16.74 11.36 0.87
0.042 0.05 0.10 2.26 0.05 0.45 remainder 0.50 0.15 0.17 3.57 No.
159 Example 16.30 10.25 0.45 0.018 0.12 0.09 2.68 0.08 0.58
remainder 1.33 0.21 0.47 11.67 No. 160 Example 16.35 13.68 1.03
0.067 0.05 0.08 2.77 0.06 0.22 remainder 0.63 0.13 0.13 1.94 No.
161 Example 16.45 14.18 0.86 0.009 0.03 0.04 2.45 0.00 0.45
remainder 0.75 0.07 0.08 7.78 No. 162 Example 16.25 12.35 0.47
0.123 0.15 0.09 2.12 0.08 0.48 remainder 1.67 0.24 0.51 1.95 No.
163 Compar- 17.11 12.29 0.74 0.064 0.00 0.05 2.18 0.15 0.29
remainder 0.00 0.05 0.07 0.78 ative Example No. 164 Compar- 16.78
12.48 0.79 0.023 0.08 0.00 2.06 0.12 0.33 remainder -- 0.08 0.10
3.48 ative Example No. 165 Compar- 16.42 13.65 0.39 0.012 0.69 0.07
2.89 0.08 0.37 remainder 9.86 0.76 1.95 63.33 ative Example No. 166
Compar- 17.21 10.88 0.42 0.021 0.06 0.61 2.98 0.13 0.35 remainder
0.10 0.67 1.60 31.90 ative Example
[0421] In Table 21, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0422] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 21 is omitted.
11. Evaluation of Metal Powder (Nb--Ta Based)
[0423] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0424] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0425] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0426] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
12. Evaluation of Sintered Body (Nb--Ta Based)
12.1 Evaluation of Relative Density
[0427] With respect to the sintered bodies of the respective sample
Nos. shown in Table 21, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0428] The calculation results are shown in Table 22.
12.2 Evaluation of Vickers Hardness
[0429] With respect to the sintered bodies of the respective sample
Nos. shown in Table 21, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0430] The measurement results are shown in Table 22.
12.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0431] With respect to the sintered bodies of the respective sample
Nos. shown in Table 21, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0432] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0433] The above evaluation results are shown in Table 22.
TABLE-US-00022 TABLE 22 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 157 Example 3.87 99.0 166 A A A No. 158 Example
4.12 99.1 167 A A B No. 159 Example 6.45 98.5 173 A A B No. 160
Example 5.82 98.3 178 B B B No. 161 Example 3.45 98.2 175 B B B No.
162 Example 3.25 97.4 181 B B C No. 163 Compar- 3.98 96.3 181 D D B
ative Example No. 164 Compar- 3.74 96.0 187 D D B ative Example No.
165 Compar- 4.21 93.8 236 D D D ative Example No. 166 Compar- 3.87
94.2 225 D D E ative Example
[0434] As apparent from Table 22, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
13. Production of Sintered Body (Y--Nb Based)
Sample Nos. 167 to 177
[0435] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 23, respectively.
TABLE-US-00023 TABLE 23 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Y) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 167 Example 16.55 12.58 0.85 0.025 0.08 0.09 2.13 0.07
0.26 remainder 0.89 0.17 0.20 6.80 No. 168 Example 17.32 12.87 0.68
0.023 0.05 0.08 2.21 0.11 0.33 remainder 0.63 0.13 0.19 5.65 No.
169 Example 16.35 12.32 0.74 0.029 0.09 0.05 2.04 0.08 0.41
remainder 1.80 0.14 0.19 4.83 No. 170 Example 16.31 14.52 0.53
0.011 0.03 0.08 2.68 0.07 0.26 remainder 0.38 0.11 0.21 10.00 No.
171 Example 17.12 13.88 0.57 0.024 0.09 0.10 2.51 0.12 0.34
remainder 0.90 0.19 0.33 7.92 No. 172 Example 16.66 11.58 1.02
0.057 0.11 0.04 2.74 0.12 0.22 remainder 2.75 0.15 0.15 2.63 No.
173 Example 16.21 13.21 0.32 0.044 0.08 0.21 2.15 0.79 0.41
remainder 0.67 0.20 0.63 4.55 No. 174 Compar- 16.55 12.74 0.84
0.026 0.00 0.06 2.24 0.13 0.32 remainder 0.00 0.06 0.17 2.31 ative
Example No. 175 Compar- 17.25 12.79 0.74 0.023 0.07 0.00 2.21 0.06
0.27 remainder -- 0.07 0.09 3.04 ative Example No. 176 Compar-
16.87 12.36 0.86 0.029 0.64 0.12 2.64 0.21 0.41 remainder 5.33 0.76
0.88 26.21 ative Example No. 177 Compar- 16.39 13.11 0.71 0.033
0.08 0.72 2.35 0.06 0.39 remainder 0.11 0.80 1.13 24.24 ative
Example
[0436] In Table 23, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0437] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 23 is omitted.
14. Evaluation of Metal Powder (Y--Nb Based)
[0438] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0439] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0440] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0441] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
15. Evaluation of Sintered Body (Y--Nb Based)
15.1 Evaluation of Relative Density
[0442] With respect to the sintered bodies of the respective sample
Nos. shown in Table 23, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0443] The calculation results are shown in Table 24.
15.2 Evaluation of Vickers Hardness
[0444] With respect to the sintered bodies of the respective sample
Nos. shown in Table 23, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0445] The measurement results are shown in Table 24.
15.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0446] With respect to the sintered bodies of the respective sample
Nos. shown in Table 23, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0447] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0448] The above evaluation results are shown in Table 24.
TABLE-US-00024 TABLE 24 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 167 Example 4.11 99.2 169 A A A No. 168 Example
3.89 99.1 170 A A A No. 169 Example 3.94 99.0 172 A A A No. 170
Example 4.23 98.7 177 B A A No. 171 Example 4.12 99.2 174 A A A No.
172 Example 3.87 98.5 180 B B B No. 173 Example 3.69 98.4 181 B B B
No. 174 Compar- 3.77 96.1 192 D D B ative Example No. 175 Compar-
3.94 95.9 196 D D B ative Example No. 176 Compar- 4.78 94.8 201 D E
E ative Example No. 177 Compar- 4.56 94.6 204 D E E ative
Example
[0449] As apparent from Table 24, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
16. Production of Sintered Body (V--Nb Based)
Sample Nos. 178 to 187
[0450] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 25, respectively.
TABLE-US-00025 TABLE 25 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (V) (Nb) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 178 Example 16.56 12.65 0.79 0.025 0.08 0.15 2.35 0.06
0.26 remainder 0.53 0.23 0.29 9.20 No. 179 Example 16.42 12.36 0.71
0.016 0.05 0.10 2.28 0.09 0.31 remainder 0.50 0.15 0.21 9.38 No.
180 Example 17.23 12.15 0.89 0.022 0.15 0.12 2.23 0.07 0.68
remainder 1.25 0.27 0.30 12.27 No. 181 Example 17.89 11.75 0.97
0.047 0.09 0.09 2.59 0.05 0.18 remainder 1.00 0.18 0.19 3.83 No.
182 Example 18.23 13.21 0.88 0.011 0.05 0.10 2.87 0.07 0.31
remainder 0.50 0.15 0.17 13.64 No. 183 Example 18.25 10.25 0.44
0.187 0.12 0.12 2.47 0.07 0.47 remainder 1.00 0.24 0.55 1.28 No.
184 Compar- 16.54 12.74 0.58 0.056 0.00 0.06 2.68 0.12 0.28
remainder 0.00 0.06 0.10 1.07 ative Example No. 185 Compar- 16.39
12.47 0.75 0.032 0.09 0.00 2.13 0.11 0.32 remainder -- 0.09 0.12
2.81 ative Example No. 186 Compar- 17.87 12.48 0.36 0.014 0.68 0.09
2.54 0.18 0.44 remainder 7.56 0.77 2.14 55.00 ative Example No. 187
Compar- 17.65 12.77 0.47 0.023 0.07 0.63 2.77 0.16 0.39 remainder
0.11 0.70 1.49 30.43 ative Example
[0451] In Table 25, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0452] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 25 is omitted.
17. Evaluation of Metal Powder (V--Nb Based)
[0453] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0454] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0455] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0456] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
18. Evaluation of Sintered Body (V--Nb Based)
18.1 Evaluation of Relative Density
[0457] With respect to the sintered bodies of the respective sample
Nos. shown in Table 25, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0458] The calculation results are shown in Table 26.
18.2 Evaluation of Vickers Hardness
[0459] With respect to the sintered bodies of the respective sample
Nos. shown in Table 25, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0460] The measurement results are shown in Table 26.
18.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0461] With respect to the sintered bodies of the respective sample
Nos. shown in Table 25, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0462] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0463] The above evaluation results are shown in Table 26.
TABLE-US-00026 TABLE 26 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 178 Example 4.12 98.9 172 A A B No. 179 Example
4.25 99.0 167 A A A No. 180 Example 6.89 98.5 175 A A B No. 181
Example 5.74 98.3 181 B B B No. 182 Example 3.25 98.7 161 B B A No.
183 Example 4.11 97.4 194 B B C No. 184 Compar- 3.98 96.2 202 D D C
ative Example No. 185 Compar- 3.74 96.0 211 D D C ative Example No.
186 Compar- 4.52 94.5 215 D D D ative Example No. 187 Compar- 3.45
94.3 223 D D E ative Example
[0464] As apparent from Table 26, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
19. Production of Sintered Body (Ti--Zr Based)
Sample Nos. 188 to 197
[0465] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Table 27, respectively.
TABLE-US-00027 TABLE 27 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Ti) (Zr) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 188 Example 16.85 12.74 0.86 0.023 0.06 0.12 2.54 0.07
0.31 remainder 0.50 0.18 0.21 7.83 No. 189 Example 17.24 12.14 0.74
0.039 0.05 0.10 2.36 0.04 0.49 remainder 0.50 0.15 0.20 3.85 No.
190 Example 16.21 12.46 0.62 0.019 0.12 0.09 2.78 0.07 0.54
remainder 1.33 0.21 0.34 11.05 No. 191 Example 16.57 12.98 0.97
0.059 0.08 0.06 2.23 0.05 0.21 remainder 1.33 0.14 0.14 2.37 No.
192 Example 17.85 12.41 0.88 0.009 0.05 0.10 2.74 0.07 0.35
remainder 0.50 0.15 0.17 16.67 No. 193 Example 17.65 13.21 0.44
0.175 0.09 0.09 2.68 0.07 0.44 remainder 1.00 0.18 0.41 1.03 No.
194 Compar- 17.44 12.47 0.72 0.055 0.00 0.06 2.75 0.18 0.26
remainder 0.00 0.06 0.08 1.09 ative Example No. 195 Compar- 16.54
12.87 0.78 0.032 0.09 0.00 2.69 0.08 0.35 remainder -- 0.09 0.12
2.81 ative Example No. 196 Compar- 16.32 13.58 0.38 0.021 0.64 0.08
2.41 0.09 0.28 remainder 8.00 0.72 1.89 34.29 ative Example No. 197
Compar- 16.25 13.75 0.43 0.018 0.07 0.59 2.21 0.06 0.22 remainder
0.12 0.66 1.53 36.67 ative Example
[0466] In Table 27, among the sintered bodies of the respective
sample Nos., those corresponding to the invention are indicated by
"Example", and those not corresponding to the invention are
indicated by "Comparative Example".
[0467] Each sintered body contained very small amounts of
impurities, but the description thereof in Table 27 is omitted.
20. Evaluation of Metal Powder (Ti--Zr Based)
[0468] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0469] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0470] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0471] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
21. Evaluation of Sintered Body (Ti--Zr Based)
21.1 Evaluation of Relative Density
[0472] With respect to the sintered bodies of the respective sample
Nos. shown in Table 27, the sintered density was measured in
accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0473] The calculation results are shown in Table 28.
21.2 Evaluation of Vickers Hardness
[0474] With respect to the sintered bodies of the respective sample
Nos. shown in Table 27, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0475] The measurement results are shown in Table 28.
21.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0476] With respect to the sintered bodies of the respective sample
Nos. shown in Table 27, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0477] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0478] The above evaluation results are shown in Table 28.
TABLE-US-00028 TABLE 28 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 188 Example 4.12 98.8 172 A A B No. 189 Example
4.25 99.0 167 A A A No. 190 Example 5.87 98.6 184 A A B No. 191
Example 5.12 98.5 191 B B B No. 192 Example 3.89 98.2 195 B B B No.
193 Example 4.47 97.4 199 B B C No. 194 Compar- 4.11 96.3 205 D D C
ative Example No. 195 Compar- 3.78 96.7 211 D D C ative Example No.
196 Compar- 4.52 94.7 235 D D E ative Example No. 197 Compar- 3.88
95.2 221 D D E ative Example
[0479] As apparent from Table 28, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
22. Production of Sintered Body (Zr--Ta Based)
Sample Nos. 198 to 212
[0480] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Tables 29 and 30,
respectively.
TABLE-US-00029 TABLE 29 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Zr) (Ta) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 198 Example 16.61 12.45 0.68 0.023 0.06 0.09 2.55 0.11
0.38 remainder 0.67 0.15 0.22 6.52 No. 199 Example 16.94 12.21 0.72
0.039 0.05 0.10 2.47 0.06 0.24 remainder 0.50 0.15 0.21 3.85 No.
200 Example 17.43 12.89 0.85 0.019 0.12 0.09 2.05 0.54 0.49
remainder 1.33 0.21 0.25 11.05 No. 201 Example 17.21 13.42 0.97
0.058 0.08 0.06 2.78 0.07 0.31 remainder 1.33 0.14 0.14 2.41 No.
202 Example 16.31 12.87 0.88 0.011 0.05 0.10 2.74 0.12 0.55
remainder 0.50 0.15 0.17 13.64 No. 203 Example 16.54 12.25 0.44
0.146 0.09 0.09 2.32 0.07 0.68 remainder 1.00 0.18 0.41 1.23 No.
204 Compar- 17.24 12.14 0.77 0.018 0.00 0.06 2.56 0.08 0.27
remainder 0.00 0.06 0.08 3.33 ative Example No. 205 Compar- 16.87
12.56 0.82 0.026 0.09 0.00 2.24 0.09 0.32 remainder -- 0.09 0.11
3.46 ative Example No. 206 Compar- 16.54 12.32 0.35 0.025 0.78 0.05
2.89 0.11 0.35 remainder 15.60 0.83 2.37 33.20 ative Example No.
207 Compar- 16.35 12.47 0.45 0.022 0.04 0.58 2.77 0.16 0.33
remainder 0.07 0.62 1.38 28.18 ative Example
TABLE-US-00030 TABLE 30 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Zr) (Ta) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 208 Example 7.04 0.35 1.78 0.240 0.12 0.18 0.00 0.72
0.49 remainder 0.67 0.30 0.17 1.25 No. 209 Example 19.08 40.31 0.44
0.540 0.04 0.08 0.00 0.79 0.34 remainder 0.50 0.12 0.27 0.22 No.
210 Example 20.69 19.77 0.54 0.420 0.06 0.15 0.00 0.84 0.36
remainder 0.40 0.21 0.39 0.50 No. 211 Compar- 19.18 40.32 0.54
0.440 0.00 0.00 0.00 0.72 0.28 remainder -- 0.00 0.00 0.00 ative
Example No. 212 Compar- 19.31 39.58 0.75 0.480 0.07 0.00 0.00 0.86
0.43 remainder -- 0.07 0.09 0.15 ative Example
[0481] In Tables 29 and 30, among the sintered bodies of the
respective sample Nos., those corresponding to the invention are
indicated by "Example", and those not corresponding to the
invention are indicated by "Comparative Example".
[0482] Each sintered body contained very small amounts of
impurities, but the description thereof in Tables 29 and 30 is
omitted.
23. Evaluation of Metal Powder (Zr--Ta Based)
[0483] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0484] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0485] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0486] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
24. Evaluation of Sintered Body (Zr--Ta Based)
24.1 Evaluation of Relative Density
[0487] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 29 and 30, the sintered density was measured
in accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0488] The calculation results are shown in Tables 31 and 32.
24.2 Evaluation of Vickers Hardness
[0489] With respect to the sintered bodies of the respective sample
Nos. shown in Table 29, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0490] The measurement results are shown in Table 31.
24.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0491] With respect to the sintered bodies of the respective sample
Nos. shown in Table 29, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0492] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0493] The above evaluation results are shown in Table 31.
TABLE-US-00031 TABLE 31 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 198 Example 4.12 99.2 172 A A A No. 199 Example
4.32 99.3 167 A A A No. 200 Example 5.74 98.7 181 A A B No. 201
Example 5.21 98.5 185 B B B No. 202 Example 4.32 98.2 189 B B B No.
203 Example 4.23 97.5 197 B B C No. 204 Compar- 3.88 96.2 199 D D C
ative Example No. 205 Compar- 4.22 96.2 199 D D C ative Example No.
206 Compar- 4.11 94.8 211 D D E ative Example No. 207 Compar- 3.89
95.1 205 D D E ative Example
TABLE-US-00032 TABLE 32 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 208 Example 14.46 98.7 -- -- -- -- No. 209
Example 7.45 98.6 -- -- -- -- No. 210 Example 6.58 99.0 -- -- -- --
No. 211 Compar- 7.98 96.1 -- -- -- -- ative Example No. 212 Compar-
8.02 95.4 -- -- -- -- ative Example
[0494] As apparent from Tables 31 and 32, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
25. Production of Sintered Body (Zr--V Based)
Sample Nos. 213 to 227
[0495] Sintered bodies were obtained in the same manner as the
method for producing the sintered body of sample No. 1 except that
the composition and the like of the metal powder for powder
metallurgy were changed as shown in Tables 33 and 34,
respectively.
TABLE-US-00033 TABLE 33 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Zr) (V) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 213 Example 16.58 12.47 0.75 0.022 0.09 0.06 2.36 0.08
0.31 remainder 1.50 0.15 0.20 6.82 No. 214 Example 16.32 12.24 0.89
0.015 0.05 0.08 2.64 0.06 0.25 remainder 0.63 0.13 0.15 8.67 No.
215 Example 16.87 12.55 0.98 0.025 0.09 0.09 2.88 0.07 0.39
remainder 1.00 0.18 0.18 7.20 No. 216 Example 17.28 12.36 0.54
0.069 0.12 0.06 2.12 0.05 0.23 remainder 2.00 0.18 0.33 2.61 No.
217 Example 17.59 12.98 0.88 0.012 0.08 0.08 2.58 0.02 0.45
remainder 1.00 0.16 0.18 13.33 No. 218 Example 17.25 12.78 0.44
0.118 0.09 0.09 2.68 0.07 0.61 remainder 1.00 0.18 0.41 1.53 No.
219 Compar- 16.34 12.63 0.77 0.054 0.00 0.06 2.84 0.08 0.36
remainder 0.00 0.06 0.08 1.11 ative Example No. 220 Compar- 16.78
12.24 0.78 0.032 0.09 0.00 2.64 0.11 0.27 remainder -- 0.09 0.12
2.81 ative Example No. 221 Compar- 16.24 12.36 0.38 0.021 0.61 0.08
2.31 0.09 0.18 remainder 7.63 0.69 1.82 32.86 ative Example No. 222
Compar- 17.12 12.89 0.45 0.025 0.08 0.59 2.15 0.05 0.24 remainder
0.14 0.62 1.49 26.80 ative Example
TABLE-US-00034 TABLE 34 Metal powder for powder metallurgy Alloy
composition (E1 + (E1 + E1 E2 E1/ E1 + E2)/ E2)/ Re- Sample Cr Ni
Si C (Zr) (V) Mo Mn O Fe E2 E2 Si C marks No. -- mass % -- mass %
-- -- -- No. 223 Example 7.12 0.38 1.74 0.260 0.11 0.17 0.00 0.92
0.45 remainder 0.65 0.28 0.16 1.08 No. 224 Example 19.22 40.25 0.43
0.480 0.05 0.03 0.00 0.75 0.36 remainder 1.67 0.08 0.19 0.17 No.
225 Example 20.64 19.68 0.89 0.360 0.09 0.05 0.00 0.84 0.36
remainder 1.80 0.14 0.16 0.39 No. 226 Compar- 19.22 40.39 0.43
0.480 0.00 0.00 0.00 0.89 0.36 remainder -- 0.00 0.00 0.00 ative
Example No. 227 Compar- 19.28 39.66 0.73 0.490 0.08 0.00 0.00 0.99
0.45 remainder -- 0.08 0.11 0.16 ative Example
[0496] In Tables 33 and 34, among the sintered bodies of the
respective sample Nos., those corresponding to the invention are
indicated by "Example", and those not corresponding to the
invention are indicated by "Comparative Example".
[0497] Each sintered body contained very small amounts of
impurities, but the description thereof in Tables 33 and 34 is
omitted.
26. Evaluation of Metal Powder (Zr--V Based)
[0498] With respect to the particles of the respective sample Nos.,
the content of Cr on the surface of the particle (Cr(0)), the
content of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)), the content of Si on the surface of the particle (Si(0)),
the content of Si at a depth of 60 nm from the surface of the
particle (Si(60)), and the content of O on the surface of the
particle (O(0)) were determined.
[0499] As a result, in the particles of the metal powders
corresponding to Example, the content of Cr on the surface (Cr(0))
fell within the range of 70% or more and 170% or less the content
of Cr at a depth of 60 nm from the surface of the particle
(Cr(60)).
[0500] Further, the content of Cr on the surface of the particle
(Cr(0)) fell within the range of 0.2% by atom or more and 15% by
atom or less.
[0501] On the other hand, in the particles of the metal powders
corresponding to Comparative Example, the content of Cr on the
surface (Cr(0)) did not fall within the above-mentioned range.
27. Evaluation of Sintered Body (Zr--V Based)
27.1 Evaluation of Relative Density
[0502] With respect to the sintered bodies of the respective sample
Nos. shown in Tables 33 and 34, the sintered density was measured
in accordance with the method for measuring the density of sintered
metal materials specified in JIS Z 2501 (2000), and also the
relative density of each sintered body was calculated with
reference to the true density of the metal powder for powder
metallurgy used for producing each sintered body.
[0503] The calculation results are shown in Tables 35 and 36.
27.2 Evaluation of Vickers Hardness
[0504] With respect to the sintered bodies of the respective sample
Nos. shown in Table 33, the Vickers hardness was measured in
accordance with the Vickers hardness test method specified in JIS Z
2244 (2009).
[0505] The measurement results are shown in Table 35.
27.3 Evaluation of Tensile Strength, 0.2% Proof Stress, and
Elongation
[0506] With respect to the sintered bodies of the respective sample
Nos. shown in Table 33, the tensile strength, 0.2% proof stress,
and elongation were measured in accordance with the metal material
tensile test method specified in JIS Z 2241 (2011).
[0507] Then, the measured values of the physical properties were
evaluated according to the above-mentioned evaluation criteria
applied to Tables 6 and 9.
[0508] The above evaluation results are shown in Table 35.
TABLE-US-00035 TABLE 35 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 213 Example 4.15 99.3 172 A A A No. 214 Example
4.26 98.9 167 A A B No. 215 Example 5.74 99.0 180 A A B No. 216
Example 5.12 99.1 178 B B B No. 217 Example 3.86 98.3 197 B B B No.
218 Example 3.65 97.5 202 B B C No. 219 Compar- 4.05 96.2 209 D D C
ative Example No. 220 Compar- 4.13 96.5 208 D D C ative Example No.
221 Compar- 4.05 94.7 225 D D E ative Example No. 222 Compar- 3.88
95.2 212 D D E ative Example
TABLE-US-00036 TABLE 36 Metal powder Evaluation results of sintered
body Average 0.2% particle Relative Vickers Tensile proof Elonga-
Sample diameter density hardness strength stress tion No. -- .mu.m
% -- -- -- -- No. 223 Example 12.68 98.6 -- -- -- -- No. 224
Example 7.27 98.5 -- -- -- -- No. 225 Example 6.39 99.0 -- -- -- --
No. 226 Compar- 7.87 96.2 -- -- -- -- ative Example No. 227 Compar-
7.99 95.5 -- -- -- -- ative Example
[0509] As apparent from Tables 35 and 36, it was confirmed that the
sintered bodies corresponding to Example each have a higher
relative density than the sintered bodies corresponding to
Comparative Example. It was also confirmed that there is a
significant difference in properties such as tensile strength, 0.2%
proof stress, and elongation between the sintered bodies
corresponding to Example and the sintered bodies corresponding to
Comparative Example.
28. Evaluation of Specularity of Sintered Body
28.1 Evaluation of Porosity Near Surface and Inside
[0510] First, each of the sintered bodies of the respective sample
Nos. shown in Table 37 was cut and the cross section was
polished.
[0511] Then, a porosity A1 near the surface of the sintered body
and a porosity A2 inside the sintered body were calculated and also
A2-A1 was calculated.
[0512] The above calculation results are shown in Table 37.
28.2 Evaluation of Specular Gloss
[0513] First, each of the sintered bodies of the respective sample
Nos. shown in Table 37 was subjected to a barrel polishing
treatment.
[0514] Then, the specular gloss of the sintered body was measured
in accordance with the method for measuring the specular gloss
specified in JIS Z 8741 (1997). The incident angle of light with
respect to the surface of the sintered body was set to 60.degree.,
and as a reference plane for calculating the specular gloss, a
glass having a specular gloss of 90 and a refractive index of 1.500
was used. Then, the measured specular gloss was evaluated according
to the following evaluation criteria.
Evaluation Criteria for Specular Gloss
[0515] A: The specularity of the surface is very high (the specular
gloss is 200 or more).
[0516] B: The specularity of the surface is high (the specular
gloss is 150 or more and less than 200).
[0517] C: The specularity of the surface is slightly high (the
specular gloss is 100 or more and less than 150).
[0518] D: The specularity of the surface is slightly low (the
specular gloss is 60 or more and less than 100).
[0519] E: The specularity of the surface is low (the specular gloss
is 30 or more and less than 60).
[0520] F: The specularity of the surface is very low (the specular
gloss is less than 30).
[0521] The above evaluation results are shown in Table 37.
TABLE-US-00037 TABLE 37 Alloy Evaluation results Sample Example/
composition A2-A1 Specular No. Comparative Example E1 E2 [%] gloss
2 Example Zr Nb 1.0 A 23 Comparative Example 0.2 E 102 Example Hf
Nb 0.9 A 111 Comparative Example 0.2 E 148 Example Ti Nb 1.2 A 152
Comparative Example 0.1 E 158 Example Nb Ta 0.6 C 163 Comparative
Example 0.1 E 167 Example Y Nb 1.2 A 174 Comparative Example 0.2 E
179 Example V Nb 0.6 C 184 Comparative Example 0.1 E 189 Example Ti
Zr 0.7 C 194 Comparative Example 0.1 E 199 Example Zr Ta 0.6 B 204
Comparative Example 0.2 E 213 Example Zr V 0.5 B 219 Comparative
Example 0.2 E
[0522] As apparent from Table 37, it was confirmed that the
sintered bodies corresponding to Example each have a higher
specular gloss than the sintered bodies corresponding to
Comparative Example. This is considered to be because the porosity
near the surface of the sintered body is low, and therefore, light
scattering is suppressed, however, the ratio of regular reflection
is increased.
* * * * *