U.S. patent number RE47,321 [Application Number 13/240,516] was granted by the patent office on 2019-03-26 for bulk amorphous refractory glasses based on the ni(-cu-)-ti(-zr)-al alloy system.
This patent grant is currently assigned to California Institute of Technology. The grantee listed for this patent is William L. Johnson, Donghua Xu. Invention is credited to William L. Johnson, Donghua Xu.
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United States Patent |
RE47,321 |
Johnson , et al. |
March 26, 2019 |
Bulk amorphous refractory glasses based on the Ni(-Cu-)-Ti(-Zr)-Al
alloy system
Abstract
Bulk amorphous alloys based on quaternary Ni--Zr--Ti--Al alloy
system, and the extension of this quaternary system to higher order
alloys by the addition of one or more alloying elements, methods of
casting such alloys, and articles made of such alloys are
provided.
Inventors: |
Johnson; William L. (Pasadena,
CA), Xu; Donghua (Knoxville, TN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Johnson; William L.
Xu; Donghua |
Pasadena
Knoxville |
CA
TN |
US
US |
|
|
Assignee: |
California Institute of
Technology (Pasadena, CA)
|
Family
ID: |
32469542 |
Appl.
No.: |
13/240,516 |
Filed: |
September 22, 2011 |
PCT
Filed: |
December 04, 2003 |
PCT No.: |
PCT/US03/38683 |
371(c)(1),(2),(4) Date: |
February 03, 2006 |
PCT
Pub. No.: |
WO2004/050930 |
PCT
Pub. Date: |
June 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
10535317 |
Dec 4, 2003 |
7591910 |
Sep 22, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C
45/04 (20130101); C22C 1/002 (20130101); C22C
45/04 (20130101); C22C 1/002 (20130101) |
Current International
Class: |
C22C
45/04 (20060101); C22C 19/03 (20060101); C22C
1/00 (20060101) |
Field of
Search: |
;148/403,429
;420/457,460 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1354274 |
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Jun 2002 |
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CN |
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010237992 |
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Mar 2003 |
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DE |
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010237992 |
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Mar 2003 |
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DE |
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2005302 |
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Apr 1979 |
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GB |
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56-112449 |
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Sep 1981 |
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JP |
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458828 |
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Oct 2001 |
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TW |
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WO 00/068469 |
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Nov 2000 |
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WO |
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WO00/68469 |
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Nov 2000 |
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WO |
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WO 03/040422 |
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May 2003 |
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WO |
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WO03/040422 |
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May 2003 |
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WO |
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Other References
Author Unknown, "Standard Practice for Conducting Dry Sand/Rubber
Wheel Abrasion Tests," Designation G65-81, source unknown, pp.
351-368. cited by applicant .
T.G. Park, Development of new Ni-based amorphous alloys containing
no metalloid that have large undercooled liquid regions, Scripta
mater 43. (2000). p. 109-114. cited by examiner .
M.H. Lee et al. Quaternary and quinary Ni-based amorphous alloys in
the 3Ni--Zr--Ti--X (X=Al,Si,P) and Ni--Zr--Ti--Si--Y (Y=Sn, Mo, Y)
systems. Mat. Res. Soc. Symp. Proc., vol. 644, (2001)
L.4.8.1-L4.8.6. cited by examiner.
|
Primary Examiner: Vincent; Sean E
Attorney, Agent or Firm: Brownstein Hyatt Farber Schreck,
LLP
Government Interests
.Iadd.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT .Iaddend.
.Iadd.The U.S. Government has certain rights in this invention
pursuant to Grant No. DAAD 19-01-1-0525 awarded by the United
States Army Research Office. .Iaddend.
Claims
What is claimed is:
1. A glass forming alloy consisting of an alloy having a
composition given by: Ni.sub.100-a-b-c-d
Ti.sub.aZr.sub.bAl.sub.cCu.sub.d, where 15<a<18,
27<b<30, 9<c<11, 3<d<7.
2. The glass forming alloy described in claim 1 wherein the alloy
has a .DELTA.Tsc of more than 40.degree. C.
3. The glass forming alloy described in claim 1 wherein the alloy
has a Vickers hardness greater than 700 Kg/mm.sup.2.
4. The glass forming alloy described in claim 1 wherein the alloy
has a yield strength of greater than 2.5 GPa.
5. The glass forming alloy described in claim 1 wherein the alloy
has a Young's modulus of greater than 140 GPa.
6. The glass forming alloy described in claim 1 wherein the alloy
has a ratio of glass transition temperature to liquidus temperature
of around 0.6 or more.
7. The glass forming alloy described in claim 1 wherein the alloy
is substantially amorphous.
8. The glass forming alloy described in claim 1 wherein the alloy
contains a ductile crystalline phase precipitate.
9. The glass forming alloy described in claim 1 wherein the
critical cooling rate is less than about 1,000.degree. C./sec.
10. A glass forming alloy consisting of an alloy having a
composition given by:
.[.Ni.sub.100-a-b-c-dTi.sub.aZr.sub.bAl.sub.cCU.sub.d.].
.Iadd.Ni.sub.100-a-b-c-dTi.sub.aZr.sub.bAl.sub.cCu.sub.d.Iaddend.,
where 15<a<18, 27<b<30, 9<c<11, 3<d<7, and
a+b+c+d is in the range of from 58 to 61.
11. The glass forming alloy described in claim 10 wherein the
critical cooling rate is less than about 1,000.degree. C./sec.
12. A three dimensional article made from the alloy of claim 1
having an amorphous phase.
13. A three dimensional article made from the alloy of claim 10
having an amorphous phase.
14. The glass forming alloy of claim 1 having a composition of
Ni.sub.40Ti.sub.16Zr.sub.28Al.sub.10Cu.sub.6.
15. The glass forming alloy of claim 1 having a composition of
Ni.sub.40Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.5.
.Iadd.16. A Ni-based glass forming alloy consisting of Ni, Ti, Zr,
and Al, wherein a critical casting thickness of the glass forming
alloy is 2 mm or more, wherein a content of Al is about 8 to about
17 atomic percent, wherein the critical casting thickness is a
maximum thickness for which fully amorphous strips are obtained by
metal mold casting..Iaddend.
.Iadd.17. The Ni-based glass forming alloy of claim 16, wherein the
atomic percent of Al is greater than 8 and less than
12..Iaddend.
.Iadd.18. The Ni-based glass forming alloy of claim 16, wherein a
content of Zr is about 25 to about 37 atomic percent..Iaddend.
.Iadd.19. The Ni-based glass forming alloy of claim 16, wherein a
content of Zr is 29 to about 37 atomic percent, wherein the
Ni-based glass forming alloy is a bulk amorphous
alloy..Iaddend.
.Iadd.20. A Ni-based glass forming alloy consisting of Ni, Ti, Zr,
Al, TM, ETM and AM, given by the formula:
(Ni.sub.1-xTM.sub.x).sub.a((TiZr).sub.1-yETM.sub.y).sub.b(Al.sub.1-zAM.su-
b.z).sub.c wherein a is in the range of from 37-49, b is in the
range of 38 to 52, c is in the range of 8 to 12 atomic percentages;
wherein ETM is a metal selected from the group consisting of Hf,
Nb, Ta, V, Cr, Mo, and W, TM is a transition metal selected from
the group of Cu, Co, Fe, Mn, and AM is an additive material
selected from the group of Si, Sn, Ge, B, Sb and wherein x is less
than 0.2, y is less than 0.2, z is less than about 0.3 and the
content of Ti is more than 13 atomic percent and the Zr content is
more than 30 atomic percent and wherein a critical casting
thickness of the glass forming alloy is 0.5 mm or more..Iaddend.
Description
.Iadd.This application claims the benefit of PCT/US2003/38683,
filed Dec. 4, 2003, published as PCT Publication No. WO2004/050930,
and provisional application No. 60/430,847 filed Dec. 4,
2002..Iaddend.
FIELD OF THE INVENTION
The present invention is directed to novel bulk solidifying
amorphous alloy compositions, and more specifically to Ni-base bulk
solidifying amorphous alloy compositions.
BACKGROUND OF THE INVENTION
Amorphous alloys (or glassy alloys or metallic glass alloys) have
typically been prepared by rapid quenching a molten material from
above the melt temperature to ambient temperature. Generally,
cooling rates of 10.sup.5.degree. C./sec have been employed to
achieve an amorphous structure in these materials. However, at such
high cooling rates, the heat cannot be extracted from thick
sections of such materials, and, as such, the thickness of articles
made from amorphous alloys has been limited to tens of micrometers
in at least in one dimension. This limiting dimension is generally
referred to as the critical casting thickness and can be related by
heat-flow calculations to the cooling rate (or critical cooling
rate) required to form the amorphous phase.
This critical thickness (or critical cooling rate) can also be used
as a measure of the processability of an amorphous alloy (or glass
forming ability of an alloy). Until the early nineties, the
processability of amorphous alloys was quite limited and amorphous
alloys were readily available only in powder form or in very thin
foils or strips with dimensions of less than 100 micrometers.
However, in the early nineties, a new class of amorphous alloys was
developed that was based mostly on Zr and Ti alloy systems. It was
observed that these families of alloys have much lower critical
cooling rates of less than 10.sup.3.degree. C./sec, and in some
cases as low as 10.degree. C./sec. Using these new alloys it was
possible to form articles of amorphous alloys having critical
casting thicknesses from about 1.0 mm to as large as about 20 mm.
As such, these alloys are readily cast and shaped into
three-dimensional objects using conventional methods such as metal
mold casting, die casting, and injection casting, and are generally
referred to as bulk-solidifying amorphous alloys (bulk amorphous
alloys or bulk glass forming alloys). Examples of such bulk
amorphous alloys have been found in the Zr--Ti--Ni--Cu--Be,
Zr--Ti--Ni--Cu--Al, Mg--Y--Ni--Cu, La--Ni--Cu--Al, and Fe-based
alloy families. These amorphous alloys exhibit high strength, a
high elastic strain limit, high fracture toughness, and other
useful mechanical properties, which are attractive for many
engineering applications.
Although a number of different bulk-solidifying amorphous alloy
formulations have been disclosed in the past, it is still desirable
to seek alloy compositions with higher temperature stability,
better corrosion resistance, higher processability, higher and
modulus, higher specific strength and modulus, and lower raw
material cost. Accordingly, a need exists to develop novel
compositions of bulk solidifying amorphous alloys which will
provide improvements in these properties and characteristics.
SUMMARY OF THE INVENTION
The present invention is directed to Ni-base bulk-solidifying
amorphous alloys, and particularly to alloys based on the
Ni--Zr--Ti--Al quaternary system.
In one exemplary embodiment, the Ni--Zr--Ti--Al quaternary system
is extended to higher alloys by adding one or more alloying
elements.
In another embodiment, the invention is directed to methods of
casting these alloys into three-dimensional bulk objects, while
retaining a substantially amorphous atomic structure. In such an
embodiment, the term three dimensional refers to an object having
dimensions of least 0.5 mm in each dimension, and preferably 1.0 mm
in each dimension. The term "substantially" as used herein in
reference to the amorphous metal alloy means that the metal alloys
are at least fifty percent amorphous by volume. Preferably the
metal alloy is at least ninety-five percent amorphous, and most
preferably about one hundred percent amorphous by volume.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features and advantages of the present invention
will be better understood by reference to the following detailed
description when considered in conjunction with the accompanying
drawings wherein:
FIG. 1a is a graphical depiction of x-ray diffraction scans of an
exemplary bulk amorphous alloy; and
FIG. 1b is a graphical depiction of differential scanning
calorimetry (DSC) plots of an exemplary bulk amorphous alloy.
DESCRIPTION OF THE INVENTION
The present invention is directed to bulk-solidifying amorphous
alloys based on a Ni--Zr--Ti--Al quaternary system, and the
extension of this ternary system to higher order alloys by the
addition of one or more alloying elements. These alloys are
referred to as Ni-based alloys herein.
Although a number of different Ni--Zr--Ti--Al combinations may be
utilized in the Ni-based alloys of the current invention, a range
of Ni content from about 27 to 58 atomic percentage, a range of Ti
content from about 8 to 22 atomic percentage, a range of Zr content
from about 13 to about 37 atomic percent, and a range of Al content
from about 5 to about 17 atomic percent are preferably
utilized.
To increase the ease of casting such alloys into larger bulk
objects, and for increased processability, a formulation having a
range of Ni content from about 37 to 49 atomic percentage, a range
of Ti content from about 13 to 20 atomic percentage, a range of Zr
content from about 25 to about 32 atomic percent, and a range of Al
content from about 8 to about 12 atomic percent is preferred. Still
more preferable is a Ni-based alloy having a range of Ni content
from about 39 to 47 atomic percentage, a range of Ti content from
about 15 to 18 atomic percentage, a range of Zr content from about
27 to about 30 atomic percent, and a range of Al content from about
9 to about 11 atomic percent.
Although only combinations of Ni, Ti, Zr and Al have been discussed
thus far, it should be understood that other elements can be added
to improve the ease of casting the Ni-based alloys of the invention
into larger bulk objects or to increase the processability of the
alloys. Additional alloying elements of potential interest are Cu,
Co, Fe, and Mn, which can each be used as fractional replacements
for Ni; Hf, Nb, Ta, V, Cr, Mo and W, which can be used as
fractional replacements for Zr and Ti; and Si, Sn, Ge, B, and Sb,
which can be used as fractional replacements for Al.
It should be understood that the addition of the above mentioned
additive alloying elements may have a varying degree of
effectiveness for improving the processability of the Ni-base
alloys in the spectrum of compositional ranges described above and
below, and that this should not be taken as a limitation of the
current invention.
Given the above discussion, in general, the Ni-base alloys of the
current invention can be expressed by the following general formula
(where a, b, c are in atomic percentages and x, y, z are in
fractions of whole):
(Ni.sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(Al.sub.1-zAM.s-
ub.z).sub.c, where a is in the range of from 27 to 58, b in the
range of 21 to 59, c is in the range of 5 to 17 in atomic
percentages; ETM is an early transition metal selected from the
group of Hf; Nb, Ta, V, Cr, Mo, and W, and preferably from the
group of Hf and Nb; TM is a transition metal selected from the
group of Mn, Fe, Co, and Cu, and preferably from the group of Cu
and Co; and AM is an additive material selected from the group of
Si, Sn, Ge, B, and Sb, and preferably from the group of Si and Sn.
In such an embodiment the following constraints are given for the
x, y and z fraction: x is less than 0.3, y is less than 0.3, z is
less than 0.3, and the sum of x, y and z is less than about 0.5,
and under the further constraint that the content of Ti content is
more than 8 atomic percent and Zr content is more than 13 atomic
percent.
Preferably, the Ni-based alloys of the current invention are given
by the formula:
(Ni.sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(Al.su-
b.1-zAM.sub.z).sub.c, where a is in the range of from 37 to 49, b
in the range of 38 to 52, c is in the range of 8 to 12 in atomic
percentages; ETM is an early transition metal selected from the
group of Hf, Nb, Ta, V, Cr, Mo, and W, and preferably from the
group of Hf and Nb; TM is a transition metal selected from the
group of Mn, Fe, Co, and Cu, and preferably from the group of Cu
and Co; and AM is an additive material selected from the group of
Si, Sn, Ge, B, and Sb, and preferably from the group of Si and Sn.
In such an embodiment the following constraints are given for the
x, y and z fraction: x is less than 0.2, y is less than 0.2, z is
less than 0.2, and the sum of x, y and z is less than about 0.3,
and under the further constraint that the content of Ti content is
more than 13 atomic percent and Zr content is more than 25 atomic
percent.
Still more preferably, the Ni-based alloys of the current invention
are given by the formula:
(Ni.sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(Al.sub.1-zAM.s-
ub.z).sub.c, where a is in the range of from 39 to 47, b in the
range of 42 to 48, c is in the range of 9 to 11 in atomic
percentages; ETM is an early transition metal selected from the
group of Hf, Nb, Ta, V, Cr, Mo, and W and preferably from the group
of Hf and Nb; TM is a transition metal selected from the group of
Mn, Fe, Co, and Cu and preferably from the group of Cu and Co; and
AM is an additive material selected from the group of Si, Sn, Ge,
B, and Sb and preferably from the group of Si and Sn. In such an
embodiment the following constraints are given for the x, y and z
fraction: x is less than 0.1, y is less than 0.1, z is less than
0.1, and the sum of x, y and z is less than about 0.2 and under the
further constraint that the content of Ti content is more than 15
atomic percent and Zr content is more than 27 atomic percent.
For increased processability, the above mentioned alloys are
preferably selected to have five or more elemental components. It
should be understood that the addition of the above mentioned
additive alloying elements may have a varying degree of
effectiveness for improving the processability within the spectrum
of the alloy compositional ranges described above and below, and
that this should not be taken as a limitation of the current
invention.
Other alloying elements can also be added, generally without any
significant effect on processability when their total amount is
limited to less than 2%. However, a higher amount of other elements
can cause a degradation in the processability of the alloys, an d
in particular when compared to the processability of the exemplary
alloy compositions described below. In limited and specific cases,
the addition of other alloying elements may improve the
processability of alloy compositions with marginal critical casting
thicknesses of less than 1.0 mm. It should be understood that such
alloy compositions are also included in the current invention.
Exemplary embodiments of the Ni-based alloys in accordance with the
invention are described in the following:
In one exemplary embodiment of the invention the Ni-based alloys
have the following general formula:
Ni.sub.100-a-b-cTi.sub.aZr.sub.bAl.sub.c, where 8<a<22,
13<b<37, 5<c<17.
In one preferred embodiment of the invention the Ni-based alloys
have the following general formula
Ni.sub.100-a-b-cTi.sub.aZr.sub.bAl.sub.c, where 13<a<20,
25<b<32, 8<c<12.
The most preferred embodiment of the ternary Ni-based alloys have
the following general formula
Ni.sub.100-a-b-cTi.sub.aZr.sub.bAl.sub.c, where 15<a<18,
27<b<30, 9<c<11.
Although higher order combinations of Ni-base alloys with five or
more elemental components can be utilized in the current invention,
in one particularly exemplary embodiment of the invention, the five
component alloy system comprises combinations of
Ni--Ti--Zr--Al--Cu, where the Ni content is from about 27 to 47
atomic percentage, the Ti content is from about 8 to 22 atomic
percentage, the Zr content is from about 13 to about 37 atomic
percent, the Cu content is up to 17 atomic percent, and the Al
content is from about 5 to about 17 atomic percent.
To increase the ease of casting such alloys into larger bulk
objects, and for increased processability, a formulation having a
range of Ni content from about 37 to 44 atomic percentage, a range
of Ti content from about 13 to 20 atomic percentage, a range of Zr
content from about 25 to about 32 atomic percent, a range of Cu
content from about 2 to 8 atomic percentage, and a range of Al
content from about 8 to about 12 atomic percent is preferred. Still
more preferable is a Ni-based alloy having a range of Ni content
from about 39 to 42 atomic percentage, a range of Ti content from
about 15 to 18 atomic percentage, a range of Zr content from about
27 to about 30 atomic percent, a range of Cu content from about 3
to about 7 atomic percent and a range of Al content from about 9 to
about 11 atomic percent.
It should be understood that other elements can be added to improve
the ease of casting the five component Ni-based alloys of the
invention into larger bulk objects or to increase the
processability of the alloys. Additional alloying elements of
potential interest are Co, Fe, and Mn, which can each be used as
fractional replacements for Ni and Cu moiety; Hf; Nb, Ta, V, Cr, Mo
and W, which can be used as fractional replacements for Zr and Ti
moiety; and Si, Sn, Ge, B, and Sb, which can be used as fractional
replacements for Al.
It should be understood that the addition of the above mentioned
additive alloying elements may have a varying degree of
effectiveness for improving the processability of the Ni-base
alloys in the spectrum of compositional ranges described above and
below, and that this should not be taken as a limitation of the
current invention.
Given the above discussion, in general, the Ni-base alloys based on
the Ni--T--Zr--Cu--Al combination can be expressed by the following
general formula (where a, b, c are in atomic percentages and x, y,
z are in fractions of whole): ((Ni
Cu).sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(Al.sub.1-zAM.s-
ub.z).sub.c, where a is in the range of from 27 to 58, b in the
range of 21 to 59, c is in the range of 5 to 17 in atomic
percentages; ETM is an early transition metal selected from the
group of Hf, Nb, Ta, V, Cr, Mo, and W, and preferably from the
group of Hf and Nb; TM is a transition metal selected from the
group of Mn, Fe, and Co, and preferably Co; and AM is an additive
material selected from the group of Si, Sn, Ge, B, and Sb, and
preferably from the group of Si and Sn. In such an embodiment the
following constraints are given for the x, y and z fraction: x is
less than 0.3, y is less than 0.3, z is less than 0.3, and the sum
of x, y and z is less than about 0.5, and under the further
constraint that the content of Ti content is more than 8 atomic
percent, Zr content is more than 13 atomic percent and Cu content
is less than 17 atomic percent.
Preferably, the Ni-based alloys of the current invention are given
by the formula:
((Ni,Cu).sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(-
Al.sub.1-zAM.sub.z).sub.c, where a is in the range of from 37 to
49, b in the range of 38 to 52, c is in the range of 8 to 12 in
atomic percentages; ETM is an early transition metal selected from
the group of Hf, Nb, Ta, V, Cr, Mo, and W, and preferably from the
group of Hf and Nb; TM is a transition metal selected from the
group of Mn, Fe, and Co, and preferably Co; and AM is an additive
material selected from the group of Si, Sn, Ge, B, and Sb, and
preferably from the group of Si and Sn. In such an embodiment the
following constraints are given for the x, y and z fraction: x is
less than 0.2, y is less than 0.2, z is less than 0.2, and the sum
of x, y and z is less than about 0.3, and under the further
constraint that the content of Ti content is more than 13 atomic
percent, Zr content is more than 25 atomic percent, and Cu content
is from about 2 to 8 atomic percentage
Still more preferably, the Ni-based alloys of the current invention
are given by the formula:
((Ni,Cu).sub.1-xTM.sub.x).sub.a((Ti,Zr).sub.1-yETM.sub.y).sub.b(Al.sub.1--
zAM.sub.z).sub.c, where a is in the range of from 39 to 47, bin the
range of 42 to 48, c is in the range of 9 to 11 in atomic
percentages; ETM is an early transition metal selected from the
group of Hf, Nb, Ta, V, Cr, Mo, and W, and preferably from the
group of Hf and Nb; TM is a transition metal selected from the
group of Mn, Fe, and Co, and preferably Co; and AM is an additive
material selected from the group of Si, Sn, Ge, B, and Sb, and
preferably from the group of Si and Sn. In such an embodiment the
following constraints are given for the x, y and z fraction: x is
less than 0.1, y is less than 0.1, z is less than 0.1, and the sum
of x, y and z is less than about 0.2, and under the further
constraint that the content of Ti content is more than 15 atomic
percent, Zr content is more than 27 atomic percent, and Cu content
is from about 3 to 7 atomic percentage.
Other alloying elements can also be added, generally without any
significant effect on processability when their total amount is
limited to less than 2%. However, a higher amount of other elements
can cause a degradation in the processability of the alloys, an
particularly when compared to the processability of the exemplary
alloy compositions described below. In limited and specific cases,
the addition of other alloying elements may improve the
processability of alloy compositions with marginal critical casting
thicknesses of less than 1.0 mm. It should be understood that such
alloy compositions are also included in the current invention.
Exemplary embodiments of the Ni-based alloys in accordance with the
invention are described in the following examples:
In one exemplary embodiment of the invention the Ni-based alloys
have the following general formula
Ni.sub.100-a-b-c-dTi.sub.aZr.sub.bAl.sub.cCu.sub.d, where
8<a<22, 13<b<37, 5<c<17, and 0<d<17.
In one preferred embodiment of the invention the Ni-based alloys
have the following general formula
Ni.sub.100-a-b-c-dTi.sub.aZr.sub.bAl.sub.cCu.sub.d, where
13<a<20, 25<b<32, 8<c<12, and 2<d<8.
The most preferred embodiment of the pentiary Ni-base alloys have
the following general formula
Ni.sub.100-a-b-c-dTi.sub.aZr.sub.bAl.sub.cCu.sub.d, where
15<a<18, 27<b<30, 9<c<11, and 3<d<7.
Alloys with these general formulations have been cast directly from
the melt into copper molds to form fully amorphous strips or rods
of thickness up to 6 mm. Examples of these bulk metallic glass
forming alloys are given in Table 1, below.
TABLE-US-00001 TABLE 1 Critical Casting Alloy Composition (at %)
Thickness (mm) Ni.sub.45Ti.sub.20Zr.sub.25Al.sub.10 2
Ni.sub.45Ti.sub.20Zr.sub.20Al.sub.10Hf.sub.5 2
Ni.sub.32.5Ti.sub.12.5Zr.sub.32.5Al.sub.10Cu.sub.12.5 3
Ni.sub.33Ti.sub.13Zr.sub.32Al.sub.10Cu.sub.12 3
Ni.sub.37Ti.sub.18Zr.sub.29Al.sub.10Cu.sub.6 3
Ni.sub.40Ti.sub.16Zr.sub.23Al.sub.10Cu.sub.6Hf.sub.5 3
Ni.sub.40Ti.sub.16Zr.sub.28Al.sub.11Cu.sub.5 3
Ni.sub.40Ti.sub.18Zr.sub.26Al.sub.10Cu.sub.6 3
Ni.sub.35Ti.sub.14Zr.sub.31Al.sub.10Cu.sub.10 4
Ni.sub.37Ti.sub.15Zr.sub.30Al.sub.10Cu.sub.8 4
Ni.sub.39Ti.sub.18Zr.sub.29Al.sub.10Cu.sub.4 4
Ni.sub.39.6Ti.sub.15.84Zr.sub.27.72Al.sub.9.9Cu.sub.5.94Si.sub.1 4
Ni.sub.40Ti.sub.16Zr.sub.28Al.sub.10Cu.sub.6 4
Ni.sub.40.5Ti.sub.16.2Zr.sub.28.3Al.sub.10Cu.sub.5 4
Ni.sub.41Ti.sub.16Zr.sub.28Al.sub.10Cu.sub.5 4
Ni.sub.41.5Ti.sub.18Zr.sub.27Al.sub.10Cu.sub.3.5 4
Ni.sub.42Ti.sub.15Zr.sub.28Al.sub.10Cu.sub.5 4
Ni.sub.43Ti.sub.19Zr.sub.26Al.sub.10Cu.sub.2 4
Ni.sub.38.7Ti.sub.17.2Zr.sub.29.8Al.sub.10Cu.sub.4.3 5
Ni.sub.39Ti.sub.17Zr.sub.29Al.sub.10Cu.sub.5 5
Ni.sub.39Ti.sub.17.5Zr.sub.28.5Al.sub.10Cu.sub.5 5
Ni.sub.39.6Ti.sub.16.9Zr.sub.29.1Al.sub.10Cu.sub.4.4 5
Ni.sub.40Ti.sub.16Zr.sub.29Al.sub.10Cu.sub.5 5
Ni.sub.40Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.5 5
Ni.sub.40Ti.sub.17Zr.sub.29Al.sub.10Cu.sub.4 5
Ni.sub.40Ti.sub.17.5Zr.sub.28.5Al.sub.10Cu.sub.4 5
Ni.sub.40.5Ti.sub.16.5Zr.sub.28Al.sub.10Cu.sub.5 5
Ni.sub.40.5Ti.sub.16.75Zr.sub.28.25Al.sub.10Cu.sub.4.5 5
Ni.sub.40.5Ti.sub.17Zr.sub.28.5Al.sub.10Cu.sub.4 5
Ni.sub.41Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.4 5
Ni.sub.41Ti.sub.17.5Zr.sub.27.5Al.sub.10Cu.sub.4 5
Ni.sub.41.5Ti.sub.17.5Zr.sub.27.5Al.sub.10Cu.sub.3.5 5
Ni.sub.39Ti.sub.16Zr.sub.29Al.sub.10Cu.sub.6 6
Ni.sub.39Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.6 6
Ni.sub.39.8Ti.sub.15.92Zr.sub.27.86Al.sub.9.95Cu.sub.5.97Si.sub.0.5
6
Ni.sub.39.8Ti.sub.16.42Zr.sub.28.36Al.sub.9.95Cu.sub.5.97Si.sub.0.5
6 Ni.sub.39.8Ti.sub.16.42Zr.sub.28.36Al.sub.9.95Cu.sub.4.97Ge.sub.1
6 Ni.sub.40Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.5 6
Ni.sub.40Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4.5Si.sub.0.5 6
Ni.sub.40Ti.sub.17Zr.sub.28.5Al.sub.10Cu.sub.4.5 6
Ni.sub.40Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.4.5Si.sub.0.5 6
Ni.sub.40.25Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4.75 6
Ni.sub.40.3Ti.sub.16.42Zr.sub.28.35Al.sub.9.95Cu.sub.4.48Si.sub.0.5
6
Ni.sub.40.4Ti.sub.16.46Zr.sub.28.43Al.sub.9.97Cu.sub.4.49Si.sub.0.3
6 Ni.sub.40.5Ti.sub.16.25Zr.sub.28.75Al.sub.10Cu.sub.4.5 6
Ni.sub.40.5Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4.5 6
Ni.sub.40.5Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4Sn.sub.1 6
Ni.sub.40.5Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.4.5 6
Ni.sub.40.75Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4.25 6
Ni.sub.41Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.4 6
Ni.sub.41Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.5 6
The above table gives the maximum thickness for which fully
amorphous strips are obtained by metal mold casting using this
exemplary formulation. Evidence of the amorphous nature of the cast
strips can be determined by x-ray diffraction spectra. Typical
x-ray diffraction spectra for fully amorphous alloy strips is
provided in FIG. 1a.
The invention is also directed to methods of casting these alloys
into three-dimensional bulk objects, while retaining a
substantially amorphous atomic structure. In such an embodiment,
the term three dimensional refers to an object having dimensions of
least 0.5 mm in each dimension. The term "substantially" as used
herein in reference to the amorphous alloy (or glassy alloy) means
that the metal alloys are at least fifty percent amorphous by
volume. Preferably the metal alloy is at least ninety-five percent
amorphous and most preferably about one hundred percent amorphous
by volume.
In general, crystalline precipitates in bulk amorphous alloys are
highly detrimental to their properties, especially to the toughness
and strength, and as such generally preferred to a minimum volume
fraction possible. However, there are cases in which, ductile
crystalline phases precipitate in-situ during the processing of
bulk amorphous alloys forming a mixture of amorphous and
crystalline phases, which are indeed beneficial to the properties
of bulk amorphous alloys especially to the toughness and ductility.
These cases of mixed-phase alloys, where such beneficial
precipitates co-exist with amorphous phase are also included in the
current invention. In one preferred embodiment of the invention,
the precipitating crystalline phases have body-centered cubic
crystalline structure.
Another measurement of the processability of amorphous alloys can
be described by defining a .DELTA.Tsc (super-cooled liquid region),
which is a relative measure of the stability of the viscous liquid
regime of the alloy above the glass transition. .DELTA.Tsc is
defined as the difference between Tx, the onset temperature of
crystallization, and Tsc, the onset temperature of the super-cooled
liquid region. These values can be conveniently determined using
standard calorimetric techniques such as DSC measurements at
20.degree. C./min. For the purposes of this disclosure, Tg, Tsc and
Tx are determined from standard DSC (Differential Scanning
Calorimetry) scans at 20.degree. C./min. Tg is defined as the onset
temperature of glass transition, Tsc is defined as the onset
temperature of super-cooled liquid region, and Tx is defined as the
onset temperature of crystallization. Other heating rates such as
40.degree. C./min, or 10.degree. C./min can also be utilized while
the basic physics of this technique are still valid. All the
temperature units are in .degree. C.
Generally, a larger .DELTA.Tsc is associated with a lower critical
cooling rate, though a significant amount of scatter exists at
.DELTA.Tsc values of more than 40.degree. C. Bulk-solidifying
amorphous alloys with a .DELTA.Tsc of more than 40.degree. C., and
preferably more than 60.degree. C., and still more preferably a
.DELTA.Tsc of 90.degree. C. and more are very desirable because of
the relative ease of fabrication.
Typical examples of DSC scans for fully amorphous strips are given
in FIG. 1b. The vertical arrows in FIG. 1b indicate the location of
the observed glass transition and the observed crystallization
temperature of an exemplary alloy which was cast up to 5 mm thick
amorphous strips. Further, Table 2, below gives the measured glass
transition temperature and crystallization temperatures obtained
for the alloys using Differential Scanning Calorimetry scans at
heating rates of 10-20 K/s. The difference between Tg and Tx,
.DELTA.T=Tx-Tg, is measure of the temperature range over which the
supercooled liquid is stable against crystallization when the glass
is heated above Tg. The value of .DELTA.T is a measure of the
"processability" of the amorphous material upon subsequent heating.
Values of this parameter are also given in Table 2, as reported
values ranging up to .DELTA.T.about.50 K are observed.
TABLE-US-00002 TABLE 2 Critical Casting Tg Tx .DELTA.T Alloy
Composition (Atomic %) Thickness (K) (K) (K)
Ni.sub.45Ti.sub.20Zr.sub.35 0.5 725 752 27
Ni.sub.45Ti.sub.20Zr.sub.27Al.sub.8 <0.5 761 802 41
Ni.sub.45Ti.sub.20Zr.sub.25Al.sub.10 2 773 818 45
Ni.sub.45Ti.sub.20Zr.sub.23Al.sub.12 <0.5 783 832 49
Ni.sub.40Ti.sub.16Zr.sub.28Al.sub.10Cu.sub.6 3.5 766 803 42
Ni.sub.40Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.5 4 762 808 46
Ni.sub.40.5Ti.sub.16.5Zr.sub.28Al.sub.10Cu.sub.5 4 764 809 45
Ni.sub.40Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.5 5 763 809 46
Ni.sub.39.8Ti.sub.15.92Zr.sub.27.86Al.sub.9.95Cu.sub.5.97Si.sub.0.5
5 768 - 815 47
To assess the strength and elastic properties of these new metallic
glasses, we have carried out measurements of the Vickers Hardness
and compression tests. Typical data are shown in Table 3, below.
Typical values range from V.H.=700 to 900. Based on this data, and
using empirical scaling rules, one can estimate the yield strength,
Y.S. of these materials. Here we have used the approximate formula:
Y.S.=(V.H.).times.3 where the approximate yield strength is given
in MPa and the Vickers Hardness is given in Kg/mm.sup.2. The yield
strength values can be as high as 2.5 GPa and among the largest
values of Y.S. of any bulk amorphous alloys reported to date.
Table 3 also gives values for Poisson ratio (.nu.), shear modulus
(.mu.) and Young's modulus (E) of exemplary alloys. These elastic
properties data were obtained by measuring the sound propagation
velocities of plane waves (longitudinal and transverse, C.sub.1 and
C.sub.s, respectively) in the alloys, then using the following
relations (valid for isotropic materials such as amorphous alloys):
.nu.=(2-x)/(2-2x)=Poisson's ratio, where x=(C.sub.1/C.sub.s).sup.2
.mu.=.rho.*C.sub.s.sup.2=shear modulus, where .rho. is density
E=.mu.*2(1+.nu.)=Young's modulus As can be seen from the data, the
Young's modulus for these new bulk amorphous alloys is relatively
large, i.e., these are relatively "stiff" bulk amorphous
alloys.
TABLE-US-00003 TABLE 3 Yield Shear Young Vickers Strength Poisson's
Modulus Modulus Alloy Composition (Atomic %) Hardness (GPa) ratio
(GPa) (GPa) Ni.sub.45Ti.sub.20Zr.sub.25Al.sub.10 791 2.37 0.36 42.7
116 Ni.sub.40Ti.sub.16Zr.sub.28Al.sub.10Cu.sub.6 780 2.2 0.361 41.5
113 Ni.sub.40Ti.sub.17Zr.sub.28Al.sub.10Cu.sub.5 862 2.3 0.348 50.1
135.1 Ni.sub.40.5Ti.sub.16.5Zr.sub.28Al.sub.10Cu.sub.5 787 2.36
0.36 42.5 115.5 Ni.sub.40Ti.sub.16.5Zr.sub.28.5Al.sub.10Cu.sub.5
800 2.4 0.355 45.6 123.7
Ni.sub.39.8Ti.sub.15.92Zr.sub.27.86Al.sub.9.95Cu.sub.5.97Si.sub.0.5
829 2.- 49 0.36 43.5 118.2
In sum, the inventors discovered a new family of bulk metallic
glass forming alloys having exceedingly high values of hardness,
elastic modulus (E), yield strength, and glass transition
temperature, Tg. The values of these characteristic properties are
among the highest reported for any known metallic alloys which form
bulk metallic glass. Here, "bulk" is taken to mean that the alloys
have a critical casting thickness of the order of 0.5 mm or more.
The properties of these new alloys make them ideal candidates for
many engineering applications.
Although specific embodiments are disclosed herein, it is expected
that persons skilled in the art can and will design alternative
Ni-based alloys that are within the scope of the following claims
either literally or under the Doctrine of Equivalents.
* * * * *