U.S. patent application number 10/581553 was filed with the patent office on 2007-07-12 for heat-resistant, high-toughness aluminum alloy, method of manufacturing the same, and engine parts.
This patent application is currently assigned to SUMITOMO ELECTRIC SINTERED ALLOY, LTD.. Invention is credited to Hiroyuki Horimura, Toshihiko Kaji, Tomoo Oka, Terukazu Tokuoka.
Application Number | 20070158003 10/581553 |
Document ID | / |
Family ID | 34650054 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070158003 |
Kind Code |
A1 |
Tokuoka; Terukazu ; et
al. |
July 12, 2007 |
Heat-resistant, high-toughness aluminum alloy, method of
manufacturing the same, and engine parts
Abstract
This invention provides a heat-resistant, high-toughness
aluminum alloy which has a good balance between strength and
ductility at a temperature from room temperature to around 300
degrees C. and has a high fracture toughness, a method of
manufacturing the same, and engine parts. The heat-resistant,
high-toughness aluminum alloy of this invention contains 10 to 16
mass. % of silicon, 1 to 3 mass % of iron, 1 to 2 mass % of nickel,
0.5 to 2 mass % in total of one or more selected from the group
consisting of titanium, zirconium, chromium and vanadium, 0.6 to 3
mass % of copper, and 0.2 to 2 mass % of magnesium, the balance
being essentially aluminum, and is obtained by densifying aluminum
alloy powder prepared by gas atomizing. The silicon has an average
grain diameter of 4 .mu.m or less.
Inventors: |
Tokuoka; Terukazu; (Hyogo,
JP) ; Kaji; Toshihiko; (Hyogo, JP) ; Horimura;
Hiroyuki; (Saitama, JP) ; Oka; Tomoo;
(Saitama, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
SUMITOMO ELECTRIC SINTERED ALLOY,
LTD.
1-1, Koyakita 1-chome, Itami-shi,
Hyogo
JP
KABUSHIKI KAISHA HONDA GIJUTSU KENKYUSHO
4-1, Chuo 1-chome, Wako-shi,
Saitama
JP
|
Family ID: |
34650054 |
Appl. No.: |
10/581553 |
Filed: |
December 2, 2004 |
PCT Filed: |
December 2, 2004 |
PCT NO: |
PCT/JP04/17949 |
371 Date: |
January 17, 2007 |
Current U.S.
Class: |
148/513 ;
148/439; 420/535 |
Current CPC
Class: |
C22F 1/043 20130101;
B22F 2003/208 20130101; B22F 3/162 20130101; B22F 2998/10 20130101;
C22C 1/0416 20130101; B22F 2998/00 20130101; B22F 3/02 20130101;
B22F 3/14 20130101; B22F 3/162 20130101; B22F 3/10 20130101; B22F
9/082 20130101; B22F 2998/10 20130101; C22C 21/02 20130101; B22F
2998/00 20130101 |
Class at
Publication: |
148/513 ;
148/439; 420/535 |
International
Class: |
C22C 21/06 20060101
C22C021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 2, 2003 |
JP |
2003-403082 |
Claims
1. A heat-resistant, high-toughness aluminum alloy comprising not
less than 10 mass % and not more than 16 mass % of silicon, not
less than 1 mass % and not more than 3 mass % of iron, not less
than 1 mass % and not more than 2 mass % of nickel, not less than
0.5 mass % and not more than 2 mass % in total of one or more
selected from the group consisting of titanium, zirconium, chromium
and vanadium, not less than 0.6 mass % and not more than 3 mass %
of copper, and not less than 0.2 mass % and not more than 2 mass %
of magnesium, the balance being essentially aluminum, said alloy
being obtained by densifying aluminum alloy powder prepared by gas
atomizing, said silicon having an average grain diameter of not
more than 4 .mu.m.
2. The heat-resistant, high-toughness aluminum alloy of claim 1
which contains titanium by not less than 0.5 mass % and not more
than 2 mass %.
3. The heat-resistant, high-toughness aluminum alloy of claim 1 or
2 having a density of 2.8 Mg/m.sup.3 or less.
4. An engine part manufactured by subjecting the heat-resistant,
high-toughness aluminum alloy of any of claims 1 to 3 to hot
plastic working.
5. The engine part of claim 4 which is a piston.
6. A method of manufacturing a heat-resistant, high-toughness
aluminum alloy comprising: preparing aluminum alloy powder by gas
atomizing, said aluminum alloy powder comprising not less than 10
mass % and not more than 16 mass % of silicon, not less than 1 mass
% and not more than 3 mass % of iron, not less than 1 mass % and
not more than 2 mass % of nickel, not less than 0.5 mass % and not
more than 2 mass % in total of one or more selected from the group
consisting of titanium, zirconium, chromium and vanadium, not less
than 0.6 mass % and not more than 3 mass % of copper, and not less
than 0.2 mass % and not more than 2 mass % of magnesium, the
balance being essentially aluminum; subjecting said aluminum alloy
powder to cold forming to obtain a preform; heating said preform to
a temperature range of not less than 400 degrees C. and not more
than 510 degrees C. and holding said preform in said temperature
range for 5 hours or less; and subjecting said preform to hot
plastic working to densify said preform, thereby obtaining a dense
body as said heat-resistant, high-toughness aluminum alloy; the
silicon in said aluminum alloy having an average grain diameter of
4 .mu.m or less.
7. A method of manufacturing a heat-resistant, high-toughness
aluminum alloy comprising: preparing aluminum alloy powder by gas
atomizing, said aluminum alloy powder comprising not less than 10
mass % and not more than 16 mass % of silicon, not less than 1 mass
% and not more than 3 mass % of iron, not less than 1 mass % and
not more than 2 mass % of nickel, not less than 0.5 mass % and not
more than 2 mass % in total of one or more selected from the group
consisting of titanium, zirconium, chromium and vanadium, not less
than 0.6 mass % and not more than 3 mass % of copper, and not less
than 0.2 mass % and not more than 2 mass % of magnesium, the
balance being essentially aluminum; subjecting said aluminum alloy
powder to cold forming to obtain a preform; heating said preform to
a temperature range of 400 degrees C. to 510 degrees C. and holding
said preform in said temperature range for 5 hours or less;
subjecting said preform to hot plastic working to densify said
preform, thereby obtaining a dense body; and subjecting said dense
body to hot plastic working by heating to a temperature not higher
than the heating temperature of said preform, thereby manufacturing
said aluminum alloy; the silicon in said aluminum alloy having an
average grain diameter of 4 .mu.m or less.
8. The method of claim 6 or 7 wherein the step of subjecting said
preform to hot plastic working includes extruding with an extrusion
ratio of 6 or more.
Description
TECHNICAL FIELD
[0001] The present invention relates to heat-resistant,
high-toughness aluminum alloys, methods of manufacturing the same,
and engine parts, and particularly to heat-resistant,
high-toughness aluminum alloys which are made by rapid
solidification and are suitable as materials for automotive engine
parts, for which high heat resistance and toughness are required,
particularly as materials for pistons.
BACKGROUND ART
[0002] Unexamined Japanese patent publication 11-293374 (patent
publication 1) discloses heat-resistant, rapidly solidified
aluminum alloys of Al (aluminum)--Si (silicon)--transition metal.
Specifically, this publication discloses aluminum alloys comprising
10 to 30 mass % of Si, 1 to 5 mass % of Ti (titanium), 3 to 10 mass
% in total of at least one of Fe (iron) and Ni (nickel), and 0.05
to 1.0 mass % of Mg (magnesium), the balance being essentially Al,
and in which the silicon has an average grain diameter of not more
than 2 .mu.m, and the intermetallic compound phase not containing
Si has an average grain diameter of not more than 1 .mu.m.
[0003] This publication also discloses that the above aluminum
alloys are used for e.g. engine parts.
Patent publication 1: Unexamined Japanese patent publication
11-293374
DISCLOSURE OF THE INVENTION
Problems to which the Invention Seeks a Solution
[0004] The aluminum alloys disclosed in the above patent
publication are suitable as materials for e.g. engine parts because
they have high heat resistance and high wear resistance. In cases
where higher load operation is required for engines, e.g. for car
races, besides high strength, high toughness and low specific
gravity, lightness in weight and high durability are also required
for engine parts, particularly for pistons. Therefore, the need for
materials which satisfy these requirements is increasing.
[0005] An object of the present invention is to provide
heat-resistant, high-toughness aluminum alloys which have a good
balance between strength and ductility at a temperature range from
room temperature to around 300 degrees C. and have high fracture
toughness, a method of manufacturing the same, and engine parts
made of such alloys.
Means to Solve the Problems
[0006] The heat-resistant, high-toughness aluminum alloy according
to the present invention comprises not less than 10 mass % and not
more than 16 mass % of silicon, not less than 1 mass % and not more
than 3 mass % of iron, not less than 1 mass % and not more than 2
mass % of nickel, not less than 0.5 mass % and not more than 2 mass
% in total of one or more selected from the group consisting of
titanium, zirconium, chromium and vanadium, not less than 0.6 mass
% and not more than 3 mass % of copper, and not less than 0.2 mass
% and not more than 2 mass % of magnesium, the balance being
essentially aluminum, the alloy being obtained by densifying
aluminum alloy powder prepared by gas atomizing, the silicon having
an average grain diameter of not more than 4 .mu.m.
[0007] Preferably, the heat-resistant, high-toughness aluminum
alloy contains titanium by not less than 0.5 mass % and not more
than 2 mass %.
[0008] Preferably, the heat-resistant, high-toughness aluminum
alloy has a density of 2.8 Mg/m.sup.3 or less.
[0009] The engine parts according to the present invention are
manufactured by subjecting any of the abovementioned
heat-resistant, high-toughness aluminum alloys to hot plastic
working.
[0010] The engine parts are preferably pistons.
[0011] One method of manufacturing a heat-resistant, high-toughness
aluminum alloy according to the present invention comprises
preparing aluminum alloy powder by gas atomizing, the aluminum
alloy powder comprising not less than 10 mass % and not more than
16 mass % of silicon, not less than 1 mass % and not more than 3
mass % of iron, not less than 1 mass % and not more than 2 mass %
of nickel, not less than 0.5 mass % and not more than 2 mass % in
total of one or more selected from the group consisting of
titanium, zirconium, chromium and vanadium, not less than 0.6 mass
% and not more than 3 mass % of copper, and not less than 0.2 mass
% and not more than 2 mass % of magnesium, the balance being
essentially aluminum, subjecting the aluminum alloy powder to cold
forming to obtain a preform, heating the preform to a temperature
range of not less than 400 degrees C. and not more than 510 degrees
C. and holding the preform in the temperature range for 5 hours or
less, and subjecting the preform to hot plastic working to densify
the preform, thereby obtaining a dense body as the heat-resistant,
high-toughness aluminum alloy, the silicon in the aluminum alloy
having an average grain diameter of 4 .mu.m or less.
[0012] Another method of manufacturing a heat-resistant,
high-toughness aluminum alloy according to the present invention
comprises preparing aluminum alloy powder by gas atomizing, the
aluminum alloy powder comprising not less than 10 mass % and not
more than 16 mass % of silicon, not less than 1 mass % and not more
than 3 mass % of iron, not less than 1 mass % and not more than 2
mass % of nickel, not less than 0.5 mass % and not more than 2 mass
% in total of one or more selected from the group consisting of
titanium, zirconium, chromium and vanadium, not less than 0.6 mass
% and not more than 3 mass % of copper, and not less than 0.2 mass
% and not more than 2 mass % of magnesium, the balance being
essentially aluminum, subjecting the aluminum alloy powder to cold
forming to obtain a preform, heating the preform to a temperature
range of 400 degrees C. to 510 degrees C. and holding the preform
in the temperature range for 5 hours or less, subjecting the
preform to hot plastic working to densify the preform, thereby
obtaining a dense body, and subjecting the dense body to hot
plastic working by heating to a temperature not higher than the
heating temperature of the preform, thereby manufacturing the
aluminum alloy, the silicon in the aluminum alloy having an average
grain diameter of 4 .mu.m or less.
[0013] In either of the above methods, the step of subjecting the
heated preform to hot plastic working preferably includes extrusion
with an extrusion ratio of 6 or more.
Advantages of the Invention
[0014] The present inventors have discovered that by preparing
aluminum alloy powder of a predetermined composition by gas
atomizing and densifying the aluminum alloy powder thus prepared,
heat-resistant, high-toughness aluminum alloys can be obtained
which have a good balance between strength and ductility at a
temperature range from room temperature to around 300 degrees C.
and have high fracture toughness. Such aluminum alloys are suitable
as materials for automotive engines parts such as pistons.
[0015] In the heat-resistant, high-toughness aluminum alloy
according to the present invention, silicon is important to improve
heat resistance while keeping a low specific gravity. The content
of silicon should be not less than 10 mass % and not more than 16
mass % because if the silicon content is less than 10 mass %, the
strength at high temperature tends to be low. If over 16 mass %,
the elongation and impact value at high temperature tend to be
low.
[0016] Iron is important to improve heat resistance. The content of
iron should be not less than 1 mass % and not more than 3 mass %
because if the iron content is less than 1 mass %, the strength at
high temperature will be low. If over 3 mass %, the elongation and
the impact value at high temperature will be low.
[0017] Nickel is important to improve heat resistance. The content
of nickel should be not less than 1 mass % and not more than 2 mass
% because if the nickel content is less than 1 mass %, the strength
at high temperature tends to be low. If over 2 mass %, the
elongation and the impact value at high temperature will be
low.
[0018] One or more of titanium, zirconium, chromium and vanadium is
important for densification of the material and to improve the
strength by forming an intermetallic compound with aluminum and
functioning as a core of crystal formation. The total content of
such one or more of titanium, zirconium, chromium and vanadium
should be not less than 0.5 mass % and not more than 2 mass %
because if it is less than 0.5 mass %, the strength at high
temperature and the strength at room temperature will be low, and
if over 2 mass %, the elongation and the impact value at high
temperature will be low.
[0019] Copper is important to improve the strength by ageing
precipitation hardening at a temperature range from room
temperature to around 200 degrees C. The content of copper should
be not less than 0.6 mass % and not more than 3 mass % because if
the copper content is less than 0.6 mass %, the strength at high
temperature and the strength at room temperature will, and if over
3 mass %, the impact value decreases and the density increases.
[0020] Magnesium has an effect similar to copper. The content of
magnesium should be not less than 0.2 mass % and not more than 2
mass % because if the magnesium content is less than 0.2 mass %,
the strength at room temperature is low, and if over 2 mass %, the
impact value and the elongation at room temperature decrease.
[0021] Since the heat-resistant, high-toughness aluminum alloys
contain titanium, which has a low specific gravity, in the amount
of not less than 0.5 mass % and not more than 2 mass %, their
specific gravity decreases, and their properties further
improve.
[0022] By setting the density of the heat-resistant, high-toughness
aluminum alloys below 2.8 Mg/m.sup.3, it is possible to reduce
their specific gravity and thus reduce the weight of parts made
therefrom.
[0023] Because the engine parts according to the present invention
are manufactured by subjecting any of the abovementioned
heat-resistant, high-toughness aluminum alloys to hot plastic
working, they satisfy the requirements for strength, toughness and
low specific gravity and are lightweight and have excellent
durability.
[0024] By either of the methods of manufacturing heat-resistant,
high-toughness aluminum alloys according to the present invention,
it is possible to manufacture heat-resistant, high-toughness
aluminum alloys which have a good balance between strength and
ductility at a temperature range from room temperature to around
300 degrees C. and have high fracture toughness. The dense body is
subjected to hot plastic working by heating at a temperature lower
than the temperature for heating the preform. It is to prevent the
ductility from decreasing.
[0025] In the methods of manufacturing heat-resistant,
high-toughness aluminum alloys according to the present invention,
extrusion is carried out with the extrusion ratio of 6 or more to
improve toughness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a flow chart showing a first method of
manufacturing the heat-resistant, high-toughness aluminum alloy
embodying the present invention;
[0027] FIG. 2 is a flow chart showing a second method of
manufacturing the heat-resistant, high-toughness aluminum alloy
embodying the present invention;
[0028] FIG. 3 is a front view of a tensile test specimen;
[0029] FIG. 4(a) is a front view of an impact test specimen;
[0030] FIG. 4(b) is a sectional view of the same; and
[0031] FIG. 4(c) is an enlarged view of a notch.
DESCRIPTION OF NUMERALS
[0032] 1 Tensile test specimen [0033] 2 Impact test specimen [0034]
2a Notch
BEST MODE FOR EMBODYING THE INVENTION
[0035] Now the embodiments of the present invention are described
with reference to the drawings.
[0036] A heat-resistant, high-toughness aluminum alloy embodying
the present invention comprises not less than 10 mass % and not
more than 16 mass % of silicon, not less than 1 mass % and not more
than 3 mass % of iron, not less than 1 mass % and not more than 2
mass % of nickel, not less than 0.5 mass % and not more than 2 mass
% in total of one or more of titanium, zirconium, chromium and
vanadium, not less than 0.6 mass % and not more than 3 mass % of
copper and not less than 0.2 mass % and not more than 2 mass % of
magnesium, the balance being essentially aluminum. The
heat-resistant, high-toughness aluminum alloy of this embodiment is
obtained by densifying aluminum alloy powder prepared by gas
atomizing. The silicon therein has an average grain diameter of not
more than 4 .mu.m.
[0037] Preferably, the heat-resistant, high-toughness aluminum
alloy according to the present invention contains titanium in the
amount of not less than 0.5 mass % and not more than 2 mass %.
Also, the heat-resistant, high-toughness aluminum alloy of this
invention preferably has a density of 2.8 Mg/m.sup.3 or less.
[0038] Pistons are manufactured by subjecting the heat-resistant,
high-toughness aluminum alloy of this invention to hot plastic
working.
[0039] Next, the methods of manufacturing the heat-resistant
high-toughness aluminum alloy embodying this invention are
described.
[0040] FIG. 1 is a flow chart showing a first method of
manufacturing a heat-resistant, high-toughness aluminum alloy
embodying the present invention. As shown in FIG. 1, a
predetermined molten composition is prepared (Step 1) which
comprises not less than 10 mass % and not more than 16 mass % of
silicon, not less than 1 mass % and not more than 3 mass % of iron,
not less than 1 mass % and not more than 2 mass % of nickel, and
not less than 0.5 mass % and not more than 2 mass % in total of one
or more of titanium, zirconium, chromium and vanadium, the balance
being essentially aluminum. Preferably, the molten composition
contains titanium in the amount of not less than 0.5 mass % and not
more than 2 mass %.
[0041] The molten composition is air atomized to prepare aluminum
alloy powder (Step S2). The aluminum alloy powder is then cold
compression molded into a preform (Step S3). The preform is heated
to a temperature of not lower than 400 degrees C. and not higher
than 510 degrees C. and maintained in this temperature range for 5
hours or less in an atmospheric furnace (Step S4). The heated
preform is densified by hot plastic working into a dense body (Step
S5). The hot plastic working is preferably extrusion with the
extrusion ratio of 6 or more. The dense body is then cut and heated
to a temperature lower than the heating temperature of the preform
(not lower than 400.degree. C. and not higher than 510.degree. C.)
and subjected to hot plastic working (Step S6). The heat-resistant,
high-toughness aluminum alloy of this embodiment is thus obtained,
the silicon therein having an average grain diameter of not more
than 4 .mu.m.
[0042] The aluminum alloy thus produced is worked into test
specimens (Step S7) which are subjected to material tests (tensile
test and Charpy impact test), to be described below (Step S8).
[0043] FIG. 2 is a flow chart showing the second method of
manufacturing a heat-resistant, high-toughness aluminum alloy
embodying the present invention. As shown in FIG. 2, this method is
the same as the method of FIG. 1 from Step S1 to Step S5. After
Step S5, the dense body densified by extrusion is cut (Step S11),
heated (Step S12), subjected to plastic working (swaging) (Step
S13) and subjected to heat treatment (Step S14).
[0044] Thereafter, in this method, too, as in the method of FIG. 1,
the aluminum alloy is worked into test specimens (Step S7), which
are subjected to material tests (tensile test and Charpy impact
test), to be described below (Step S8).
EXAMPLE 1
[0045] Examples of the present invention are now described.
[0046] Molten compositions shown in Table 1 were prepared and
formed into tensile test specimens and impact test specimens
according to the flow of FIG. 1. FIGS. 3 and 4 show a tensile test
specimen and an impact test specimen, respectively. FIG. 3 is a
front view of the tensile test specimen 1. FIG. 4(a) is a front
view of the impact test specimen 2, FIG. 4(b) is its sectional
view, and FIG. 4(c) is its enlarged view showing its notch 2a.
[0047] For these test specimens, measurements were made of the
average grain diameter of the silicon, tensile strength and
elongation at 300 degrees C., tensile strength and elongation at
room temperature (20 degrees C.), impact value and density. Table 2
shows the results. Table 2 also shows the solidifying temperature
of the preform formed into the respective test specimens, holding
time after heating the preform, and extrusion ratio, solution
treatment temperature, and artificial ageing temperature for the
heated preform. TABLE-US-00001 TABLE 1 Specimen Content(mass %) No.
Si Fe Ni Ti Cr Zr V Cu Mg Example of 1 10 2 1.3 1.1 -- -- -- 1 0.5
the invention 2 12 2.1 1.6 1.2 -- -- -- 0.9 0.7 3 13 2.1 1.4 0.9 --
-- -- 1.1 0.7 4 15 1.9 1.5 1.6 -- -- -- 1.3 0.6 5 16 2.1 1.4 1.4 --
-- -- 1.4 0.8 6 13 1.1 2.1 1 -- -- -- 1.5 1 7 13 2.8 1.1 1.5 -- --
-- 1.4 0.6 8 13 2.1 1.1 1.3 -- -- -- 1.3 1 9 13 1.2 2.9 1.2 -- --
-- 1 1.1 10 13 2 14 0.5 -- -- -- 1.1 0.5 11 13 1.8 1.3 1.8 -- -- --
0.9 0.8 12 13 1.8 1.5 -- 1.2 -- -- 0.8 0.6 13 13 1.9 1.6 -- -- --
1.3 1.1 0.5 14 13 1.8 1.4 -- -- 1.2 -- 1 0.8 15 13 1.9 1.5 1.1 --
-- -- 0.6 0.9 16 13 2 1.3 1 -- -- -- 2.8 1 17 13 1.8 1.5 1 -- -- --
0.9 0.4 18 13 2.1 1.6 1.3 -- -- -- 1.1 1.5 Comparative 19 8 2.3 1.6
0.9 -- -- -- 1.1 0.5 Example 20 18 2 1.5 1.2 -- -- -- 1.4 0.6 21 13
4 -- 1 -- -- -- 1.2 0.8 22 13 -- 4.2 1.1 -- -- -- 1.1 0.7 23 13 3
2.8 0.8 -- -- -- 1 1 24 13 0.8 0.5 0.8 -- -- -- 1.2 0.8 25 13 2.2
1.4 2.2 -- -- -- 1 1 26 13 2.1 1.3 0.2 -- -- -- 1 0.9 27 13 2.1 1.4
1.1 -- -- -- 3.5 0.7 28 13 2.1 1.5 1 -- -- -- 0.2 0.8 29 13 2 1.3
0.9 -- -- -- 0.9 2.5 30 13 2.4 1.5 0.9 -- -- -- 0.8 0.1
[0048] TABLE-US-00002 TABLE 2 Solidi- Holding Solution Artificial
Grain Tensile Elongation Tensile Elongation Impact Speci- fying
time after Extru- treatment ageing size strength at strength at
Value Density men temp. heating sion temp temp of SI at 20.degree.
C. 300.degree. C. at 20.degree. C. 20.degree. C. (J/ (Mg/ No.
(.degree. C.) (min) ratio (.degree. C.) (.degree. C.) (.mu.m) (MPa)
(%) (MPa) (%) cm.sup.2) m.sup.3) Example 1 480 60 8 470 200 1.9 105
35 390 10.0 4.5 2.75 of the 2 480 60 8 470 200 2.2 110 31 400 9.5
3.9 2.74 Invention 3 480 60 8 470 200 1.7 120 30 410 6.0 2.7 2.74 4
480 60 8 470 200 1.8 128 28 420 5.5 2.4 2.73 5 480 60 8 470 200 2.5
135 20 432 3.5 2.3 2.72 6 480 60 8 470 200 1.7 105 33 402 5.0 3.8
2.71 7 480 60 8 470 200 1.8 130 28 423 3.7 2.2 2.76 8 480 60 8 470
200 2.2 115 31 410 4.1 3.1 2.74 9 480 60 8 470 200 2.1 125 29 435
3.5 2.1 2.74 10 480 60 8 470 200 2.3 121 31 400 4.5 3.6 2.73 11 480
60 8 470 200 2.6 135 25 441 3.4 2.2 2.72 12 480 60 8 470 200 2.1
131 30 450 3.1 2.5 2.74 13 480 60 8 470 200 2.0 125 27 443 3.3 2.4
2.75 14 480 60 8 470 200 2.1 130 28 440 3.5 2.6 2.73 15 480 60 8
470 200 2.2 110 33 410 7.2 3.1 2.68 16 480 60 8 470 200 1.8 115 29
430 4.5 2.2 2.79 17 480 60 8 470 200 1.7 118 31 405 7.0 3.1 2.74 18
480 60 8 470 200 2.1 120 35 440 3.1 2.1 2.72 Compar- 19 480 60 8
470 200 1.8 65 40 370 13.0 4.9 2.78 ative 20 480 60 8 470 200 2.8
170 15 390 2.4 1.8 2.72 Example 21 480 60 8 470 200 2.1 110 16 430
2.8 1.8 2.75 22 480 60 8 470 200 2.3 100 15 440 1.8 1.7 2.75 23 480
60 8 470 200 2.1 180 12 460 1.9 1.2 2.77 24 480 60 8 470 200 2.0 70
32 380 9.1 5.2 2.70 25 480 60 8 470 200 2.5 135 15 470 1.8 1.5 2.75
26 480 60 8 470 200 1.8 80 35 370 5.5 3.5 2.71 27 480 60 8 470 200
1.9 110 29 430 3.0 2 2.80 28 480 60 8 470 200 2.3 90 36 380 5.0 3.6
2.70 29 480 60 8 470 200 2.2 110 38 460 1.0 0.8 2.70 30 480 60 8
470 200 2.4 105 29 370 7.0 3 2.75
[0049] The results in Tables 1 and 2 for Examples No. 1 to No. 5 of
the invention and Comparative Examples No. 19 and No. 20 show that
by adjusting the content of silicon to not less than 10 mass % and
not more than 16 mass %, the material revealed strength and
toughness in a balanced manner. Where the content of silicon was
over 16 mass %, ductility was not good (Comparative Example No.
20). Where the silicon content was less than 10 mass %, the
strength decreased (Comparative Example No. 19).
[0050] The results for Examples No. 6 to No. 9 and Comparative
Examples No. 21 to No. 24 show that by adjusting the contents of Fe
and Ni to ranges of not less than 1 mass % and not more than 3 mass
% and not less than 1 mass % and not more than 2 mass %,
respectively, the material revealed strength and toughness in a
balanced manner. When the Fe content alone or the Ni content alone
is increased above the above range in an attempt to improve the
heat resistance, coarse intermetallic compounds deposited, thus
impairing toughness (Comparative Examples No. 21 and No. 22). When
their contents were below the above ranges, heat resistance was
impaired. When the material contained both Fe and Ni, if their
contents were over the respective ranges, coarse intermetallic
compounds deposited, thus impairing toughness (Comparative Example
No. 23). When their contents were below the respective ranges, the
heat resistance was impaired (Comparative Example No. 24).
[0051] The results for Examples No. 10 to No. 14 of the invention
and Comparative Examples No. 25 and No. 26 show that by adjusting
the content of Ti to not less than 0.5 mass % and not more than 2
mass %, the material revealed strength and toughness in a balanced
manner. Similar effects were obtained by adding Zr, Cr, or V in
place of Ti. When the total content of these components (Ti, Zr,
Cr, V) was over 2 mass %, toughness was impaired (Comparative
Example No. 25). When it was less than 0.5 mass %, the strength
decreased (Comparative Example No. 26).
[0052] The results for Examples No. 15 and No. 16 of the invention
and Comparative Examples No. 27 and No. 28 show that by adjusting
the content of Cu to not less than 0.6 mass % and not more than 3
mass %, the material revealed strength and toughness in a balanced
manner. When the content of Cu was over 3 mass %, the density
unduly increased (Comparative Example No. 27), and when it was less
than 0.6 mass %, the strength decreased (Comparative Example No.
28).
[0053] The results for Examples No. 17 and No. 18 of the invention
and Comparative Examples No. 29 and No. 30 show that by adjusting
the content of Mg to not less than 0.2 mass % and not more than 2
mass %, the material revealed strength and toughness in a balanced
manner. When the content of Mg was over 2 mass %, the toughness
decreased (Comparative Example No. 29), and when it was less than
0.2 mass %, the strength decreased (Comparative Example No.
30).
EXAMPLE 2
[0054] It was checked how the heating conditions during
densification affect the characteristics.
[0055] Molten compositions shown in Table 3 were prepared and
formed into tensile test specimens and impact test specimens
according to the flow of FIG 1. FIGS. 3 and 4 show a tensile test
specimen and an impact test specimen, respectively.
[0056] For these test specimens, measurements were made of the
average grain diameter of the silicon, tensile strength and
elongation at 300 degrees C, tensile strength and elongation at
room temperature (20 degrees C.), impact value and density. Table 4
shows the results. Table 4 also shows the solidifying temperature
of the preform formed into the respective test specimens, holding
time after heating the preform, and extrusion ratio, solution
treatment temperature, and artificial ageing temperature for the
heated preform. TABLE-US-00003 TABLE 3 Specimen Content (mass %)
No. Si Fe Ni Ti Cr Zr V Cu Mg Example of 31 13 2.1 1.4 0.9 -- -- --
1.1 0.7 the invention 32 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 33 13 2.1
1.4 0.9 -- -- -- 1.1 0.7 34 13 2.1 1.4 0.9 -- -- -- 1.1 0.7
Comparative 35 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 Example 36 13 2.1
1.4 0.9 -- -- -- 1.1 0.7 Example of 37 13 2.1 1.4 0.9 -- -- -- 1.1
0.7 the invention 34 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 38 13 2.1 1.4
0.9 -- -- -- 1.1 0.7 Comparative 39 13 2.1 1.4 0.9 -- -- -- 1.1 0.7
Example
[0057] TABLE-US-00004 TABLE 4 Solidi- Holding Solution Artificial
Grain Tensile Elongation Tensile Elongation fying time after
treatment ageing size strength at strength at Impact Density
Specimen temp heating Extrusion temp. temp of Si at 300.degree. C.
300.degree. C. at 20.degree. C. 20.degree. C. value (Mg/ No.
(.degree. C.) (min) ratio (.degree. C.) (.degree. C.) (.mu.m) (MPa)
(%) (MPa) (%) (J/cm.sup.2) m.sup.3) (1) 31 400 60 8 390 200 1.5 145
22 420 3.5 2.5 2.74 32 430 60 8 420 200 1.5 130 28 411 4.5 2.7 2.74
33 480 60 8 470 200 1.7 120 30 410 6.0 2.7 2.74 34 510 60 8 500 200
2.5 115 33 403 6.5 3.4 2.74 (2) 35 530 60 8 520 200 4.5 105 20 360
2.4 2.0 2.74 36 380 60 8 370 200 1.4 148 19 430 2.1 1.7 2.74 (1) 37
510 30 8 500 200 1.9 120 32 420 5.7 2.8 2.74 34 510 180 8 500 200
2.5 115 33 403 6.5 3.4 2.74 38 510 270 8 500 200 2.8 100 36 380 6.6
3 2.74 (2) 39 510 330 8 500 200 3.3 85 30 360 4.1 2.5 2.74 (1)
Example of the invention (2) Comparative Example
[0058] The results in Tables 3 and 4 for Examples No. 31 to No. 34
of the invention and Comparative Examples No. 35 and No. 36 show
that by setting the heating and holding temperature of the preform
in the solidifying step to a range of 400 degrees C. to 510 degrees
C., the material revealed strength and toughness in a balanced
manner. When the solidifying temperature was higher than 510
degrees C., not only strength decreased but also the silicon
crystals became coarse and functioned as a source of stress
concentration, so that ductility decreased (Comparative Example No.
35). When the solidifying temperature was lower than 400 degrees C,
strength increased, but toughness was impaired (Comparative Example
No. 36).
[0059] The results for Examples No. 37 and No. 38 and Comparative
Example No. 39 show that by setting the holding time after heating
to solidify the preform to not longer than 5 hours, it was possible
to prevent the decrease of strength and the decrease of ductility
due to coarsening of silicon crystals. When the holding time after
heating was longer than 5 hours, both strength and ductility
decreased (Comparative Example No. 39).
EXAMPLE 3
[0060] The effects of the plastic working method in densification
have been examined.
[0061] Molten compositions shown in Table 5 were prepared and
formed into tensile test specimens and impact test specimens
according to the flow of FIG. 1. FIGS. 3 and 4 show a tensile test
specimen and an impact test specimen, respectively.
[0062] For the test specimens thus prepared, measurements were made
of the average grain diameter of the silicon therein, tensile
strength and elongation at 300 degrees C., tensile strength and
elongation at room temperature (20 degrees C.), impact value and
density. Table 6 shows the results. Table 6 also shows the
solidifying temperature for the perform in preparing the test
specimens, holding time after heating the preform, and extrusion
ratio, solution treatment temperature and artificial ageing
temperature for the heated preform. TABLE-US-00005 TABLE 5 Specimen
Content (mass %) No. Si Fe Ni Ti Cr Zr V Cu Mg Example of 40 13 2.1
1.4 0.9 -- -- -- 1.1 0.7 the invention 41 13 2.1 1.4 0.9 -- -- --
1.1 0.7 42 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 43 13 2.1 1.4 0.9 -- --
-- 1.1 0.7 Comparative 44 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 Example
45 13 2.1 1.4 0.9 -- -- -- 1.1 0.7
[0063] TABLE-US-00006 TABLE 6 Solidi- Holding Solution Artificial
Grain Tensile Elongation Tensile Elongation fying time after
treatment ageing size strength at Strength at Impact Specimen temp.
heating Extrusion temp. temp. of Si at 300.degree. C. 300 .degree.
C. at 20.degree. C. 20.degree. C. value Density No. (.degree. C.)
(min) ratio (.degree. C.) (.degree. C.) (.mu.m) (MPa) (%) (MPa) (%)
(J/cm.sup.2) (Mg/M.sup.3) (1) 40 480 60 6 470 200 1.5 145 30 420
4.5 2.5 2.74 41 480 60 8 470 200 1.5 142 32 425 4.5 2.7 2.74 42 480
60 10 470 200 1.7 144 32 430 5.0 2.7 2.74 43 480 60 12 470 200 1.8
140 35 425 6.5 2.8 2.74 (2) 44 480 60 2 470 200 2.0 105 6 360 0.8
0.5 2.73 45 480 60 4 470 200 1.5 110 8 370 0.9 0.6 2.74 (1) Example
of the invention (2) Comparative Example
[0064] The results in Tables 5 and 6 for Examples No. 40 to No. 43
of the invention and Comparative Examples Nos. 44 and 45 show that
when extrusion is used in the densifying step, by setting the
extrusion ratio to not less than 6, the material revealed strength
and toughness in a balanced manner. When the extrusion ratio was
less than 6, the toughness decreased remarkably (Comparative
Examples Nos. 44 and 45).
EXAMPLE 4
[0065] The material of Example No. 4 of the invention prepared in
Example 1 was subjected to hot plastic working according to the
flow of FIG. 2. From the material thus prepared, specimens of
shapes shown in FIGS. 3 and 4 were cut out and evaluated to
determine their characteristics. The manufacturing conditions and
the results of evaluation are shown in Tables 7 and 8.
TABLE-US-00007 TABLE 7 Specimen Content (mass %) No. Si Fe Ni Ti Cr
Zr V Cu Mg Example of 46 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 the
invention 47 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 48 13 2.1 1.4 0.9 --
-- -- 1.1 0.7 49 13 2.1 1.4 0.9 -- -- -- 1.1 0.7 Comparative 50 13
2.1 1.4 0.9 -- -- -- 1.1 0.7 Example 51 13 2.1 1.4 0.9 -- -- -- 1.1
0.7
[0066] TABLE-US-00008 TABLE 8 Holding Heating Artifi- Tensile Im-
Solidi- time temp. of Solution cial Grain Tensile Elongation
strength Elongation pact Speci- fying after Extru- extruded
treatment ageing size strength at at at at value Density men temp
heating sion moterial temp. temp of Si 300.degree. C. 300.degree.
C. 20.degree. C. 20.degree. C. (J/ (Mg/ No. (.degree. C.) (min)
ratio (.degree. C.) (.degree. C.) (.degree. C.) (.mu.m) (MPa) (%)
(MPa) (%) cm.sup.2) m.sup.3) (1) 46 480 60 8 400 470 200 1.8 145 35
420 5.0 3 2.74 47 480 60 8 450 470 200 1.9 142 38 425 5.5 3.5 2.74
48 480 60 8 460 470 200 1.8 141 40 422 6.0 3.3 2.74 49 480 60 8 480
470 200 2.0 135 42 420 6.5 3.2 2.74 (2) 50 480 60 8 500 490 200 4.5
95 25 380 4.0 2.8 2.74 51 480 60 8 520 500 200 6.4 90 18 370 3.0 2
2.74 (1) Example of the invention (2) Comparative Example
[0067] The results for Examples No. 46 to No. 49 of the invention
and Comparative examples Nos. 50 and 51 show that among the
characteristics of the materials obtained by hot plastic working at
a higher temperature than the solidifying temperature for the
extruded material, both strength and ductility decreased
(comparative examples Nos. 50 and 51).
[0068] All the embodiments and examples disclosed herein should be
considered to be not restrictive but exemplary in all respects. The
scope of the present invention should be defined not by the above
description but by the claims and includes all and any
modifications falling in the meanings and scope of the claims.
INDUSTRIAL APPLICABILITY
[0069] The heat-resistant, high-toughness aluminum alloys according
to the present invention are advantageously used as materials for
automotive engine parts for which heat resistance and toughness are
required, particularly as materials for pistons.
* * * * *