U.S. patent application number 13/026872 was filed with the patent office on 2012-08-16 for high strength aluminum alloy.
This patent application is currently assigned to Gamma Technology, LLC. Invention is credited to William C. Harrigan, JR..
Application Number | 20120207640 13/026872 |
Document ID | / |
Family ID | 46637013 |
Filed Date | 2012-08-16 |
United States Patent
Application |
20120207640 |
Kind Code |
A1 |
Harrigan, JR.; William C. |
August 16, 2012 |
HIGH STRENGTH ALUMINUM ALLOY
Abstract
High strength aluminum alloys and methods for producing them.
The alloys consist essentially of about 9.0 to 10.3 wt. % zinc,
about 2.5 to 3.5 wt. % magnesium, about 1.5 to 3.0 wt. % copper and
less than about 0.05 wt. % of any other alloying constituent. The
balance consists of aluminum. These alloys are compatible with
ceramic reinforcements used in metal matrix composites.
Inventors: |
Harrigan, JR.; William C.;
(Porter Ranch, CA) |
Assignee: |
Gamma Technology, LLC
Valencia
CA
|
Family ID: |
46637013 |
Appl. No.: |
13/026872 |
Filed: |
February 14, 2011 |
Current U.S.
Class: |
419/13 ; 148/417;
419/10; 419/17; 419/19; 419/32; 420/532 |
Current CPC
Class: |
C22C 32/00 20130101;
C22F 1/053 20130101; C22C 47/14 20130101; C22C 21/10 20130101 |
Class at
Publication: |
419/13 ; 420/532;
148/417; 419/32; 419/17; 419/10; 419/19 |
International
Class: |
B22F 1/00 20060101
B22F001/00; B22F 3/24 20060101 B22F003/24; B22F 3/02 20060101
B22F003/02; C22C 21/10 20060101 C22C021/10; C22F 1/053 20060101
C22F001/053 |
Claims
1. An aluminum alloy consisting essentially of about 9.0 to 10.3
wt. % zinc, about 2.5 to 3.5 wt. % magnesium, about 1.5 to 3.0 wt.
% copper and less than about 0.5 wt. % of any other alloying
constituent, the balance aluminum.
2. A metal matrix composite comprising a metal phase consisting
essentially of about 9.0 to 10.3 wt. % zinc, about 2.5 to 3.5 wt. %
magnesium, about 1.5 to 3.0 wt. % copper and less than about 0.5
wt. % of any other alloying constituent, the balance aluminum, and
a reinforcement phase selected from the group consisting of silicon
carbide, silicon nitride, SiAlON, titanium nitride, titanium
carbide, titanium silicide, molybdenum silicide, nickel aluminate,
boron carbide, aluminum nitride, aluminum oxide, magnesium oxide,
silicon and mixtures thereof.
3. The metal matrix composite of claim 2 wherein the metal phase
comprises about 50 to 99 vol. %.
4. The metal matrix composite of claim 2 wherein the reinforcement
phase is selected from the group consisting of particulates,
whiskers, fibers and mixtures thereof.
5. A method for producing a high strength aluminum alloy product
comprising: (a) providing an aluminum-base alloy consisting
essentially of about 9.0 to 10.3 wt. % zinc, about 2.5 to 3.5 wt. %
magnesium, about 1.5 to 3.0 wt. % copper and less than about 0.5
wt. % of any other alloying constituent, the balance aluminum; (b)
working the alloy into a product; (c) heat treating the product;
(d) quenching the heat treated product; and (e) aging the product
within a temperature range of about 235.degree. F. to 270.degree.
F. for at least 6 hours.
6. A method for producing a high strength aluminum alloy matrix
composite product comprising: (a) providing an aluminum-base metal
phase consisting essentially of about 9.0 to 10.3 wt. % zinc, about
2.5 to 3.5 wt. % magnesium, about 1.5 to 3.0 wt. % copper, and not
more than about 0.5 wt. % of any other alloying constituent, the
balance aluminum; (b) blending said metal phase with at least one
reinforcement phase consisting essentially of a gradation of
particles sizes having 90% less than minus 325 mesh; (c) working
said blended metal phase and reinforcement phase to produce a
product; (d) heat treating said product; (e) quenching said
product; and (f) aging said product within a temperature range of
about 235.degree. F. to 270.degree. F. for at least 6 hours.
7. The method of claim 6 in which said reinforcement phase is
selected from the group of particulates, whiskers, fibers and
mixtures thereof.
8. The method of claim 6 in which said reinforcement phase is
selected from the group consisting of silicon carbide, silicon
nitride, SiAlON, titanium nitride, titanium carbide, titanium
silicide, molybdenum silicide, nickel aluminate, boron carbide,
aluminum nitride, aluminum oxide, magnesium oxide, silicon and
mixtures thereof.
9. The method of claim 6 in which said blended metal phase and
reinforcement phase comprises 50 to 99 vol. % of said metal powder
phase and 1 to 50 vol. % of said reinforcement phase.
10. The method of claim 6 in which said metal phase comprises a
pre-alloyed powder.
11. The method of claim 6 in which said metal phase comprises a
mixture containing at least one elemental powder.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to the field of aluminum
alloys and, more particularly, to alloys produced by powder
metallurgy processes. Such alloys are compatible with ceramic
reinforcements used in metal matrix composites.
[0003] 2. Background Art
[0004] The development of a high strength aluminum alloys based on
the Al--Zn--Cu--Mg alloy system for many years has focused on three
main approaches: (1) heat treatment variation to maximize property
combinations, (2) thermal-mechanical treatments and (3) second
phase chemistry control.
SUMMARY OF THE INVENTION
[0005] The present invention provides aluminum alloy products
having improved strength and fatigue resistance. The present
invention further provides a method of producing improved aluminum
alloys by powder metallurgy processes. These alloys are compatible
with ceramic reinforcements used in metal matrix composites. These
alloys are characterized by high yield strength and elastic modulus
at room temperature and are therefore useful in aircraft and other
demanding applications.
[0006] In one embodiment, an aluminum alloy consists essentially of
about 9.0 to 10.3 wt. % zinc, about 2.5 to 3.5 wt. % magnesium,
about 1.5 to 3.0 wt. % copper and less than about 0.5 wt. % of any
other alloying constituent. The balance consists of aluminum,
although it will be understood that there may also be trace amounts
of unavoidable incidental impurities. This new alloy has at least
about 10% greater yield strength than 7050-T6 aluminum, one of the
strongest aluminum alloys currently in wide use for demanding
aerospace applications.
DETAILED DESCRIPTION OF THE INVENTION
[0007] In the following description, for purposes of explanation
and not limitation, specific numbers, dimensions, materials, etc.
are set forth in order to provide a thorough understanding of the
present invention. However, it will be apparent to one skilled in
the art that the present invention may be practiced in other
embodiments that depart from these specific details. In other
instances, detailed descriptions of well-known speaker components
are omitted so as not to obscure the description of the present
invention with unnecessary detail.
[0008] Aluminum alloys in accordance with embodiments of the
present invention are made by powder metallurgy processes, such as
vacuum-hot-pressing or cold-isostatic pressing and sintering. The
alloys can be made by blending elemental powders with aluminum
powders to create the desired alloy. The alloys can also be made by
blending aluminum powder with master alloys containing the desired
alloy ingredients. The alloy powders can also be made by atomizing
a melt with the desired composition. In particular embodiments, the
alloy contains aluminum with between 9.0 and 10.3 percent zinc, 2.5
and 3.5 percent Mg, 1.5 and 2.2 percent copper and less than about
0.5 percent (preferably less than about 0.05 percent) of any other
alloying constituent. This alloy can be used as the matrix for a
particle reinforced composite. The alloy is made with fine powders
in order to control the grain size and microstructure of the final
product. The maximum particle size for the powder is 44
microns.
[0009] The fine powders for this alloy are blended in commercial
units that are compatible with fine aluminum alloys. A ceramic
powder that will act as a reinforcement can be added to the alloy
powder and blended at this time. Ceramic materials suitable for use
as the reinforcement phase include silicon carbide, silicon
nitride, SiAlON, titanium nitride, titanium carbide, titanium
silicide, molybdenum silicide, nickel aluminate, boron carbide,
aluminum nitride, aluminum oxide, magnesium oxide, silicon and
mixtures thereof. The powders may be isostatically compressed into
a cohesive or coherent shape. This can be effected by placing the
powders within a bag, such as a rubber or plastic material, which
in turn is placed within a hydraulic media for transmitting
pressure through the bag to the powder. Pressures are then applied
in the range of 5 to 60 psi which compress the powder into a
cohesive shape of about 85 to 93% of full density. This isostatic
compaction step facilitates handling of the powder. The
isostatically compacted material can then be sintered by placing
the compact in a vacuum furnace and heating to temperatures of
875.degree. F., preferably 900.degree. or 950.degree. F., while
continuing to pull a vacuum down to a pressure level of one torr,
preferably 10.sup.-1 or 10.sup.-2 torr or less (1 torr=1 mm Hg at
0.degree. C.). The density of the sintered billets remain between
90 and 95 percent of the theoretical and must be metal worked by
extrusion, forging or rolling in order to develop full density and
full properties.
[0010] Alternatively, the material can be compacted to
substantially full density at relatively high temperatures. This
can be effected by placing the powder or compacted material in a
hard tool that is placed in a container and evacuating the
container at room temperature and heating to temperatures of
675.degree. F., preferably 700.degree. or 850.degree. to
950.degree. F., while continuing to pull a vacuum down to a
pressure level of one torr, preferably 10.sup.-1 or 10.sup.-2 torr
or less (1 torr=1 mm Hg at 0.degree. C.). While still in the sealed
container, the material is compressed to substantially full density
at temperatures of 900.degree. to 950.degree. F.
[0011] When referring to substantially full density, it is intended
that the compacted billet be substantially free of porosity with a
density equal to 95% or more of the theoretical solid density,
preferably 98 or 99% or more. It is desired that the vacuum
compaction to full density be effected at a minimum temperature
greater than 650.degree. F., for instance 675.degree. F. or higher,
and preferably at a minimum temperature of 700.degree. F. or
higher. The maximum temperature for compaction should not exceed
960.degree. F. After being compacted to substantially full density
at elevated temperature and vacuum conditions as just described the
billet which can then be shaped such as by forging, rolling,
extruding or the like or can be machined into a useful shape. It is
preferred that the billet be worked by any amount equivalent to a
reduction in cross section of at least 25%, preferably 50 or 60% or
more, where practical, since such favors improved elongation
properties. Preferred working temperatures range from 550.degree.
to 850.degree. F.
[0012] After working the product, it is heat treated to the desired
condition and quenched. The product is then aged within a
temperature range of about 235.degree. F. to 270.degree. F. for
about 6 to 60 hours.
[0013] Several materials were made with fine powders with different
chemical contents. The zinc content was varied from 8.4 to 11
percent, the magnesium content was varied between 2 and 2.9 percent
and the copper content was varied between 1.25 and 2 percent. The
alloy billets were extruded into 0.625 inch diameter rods from a
3.5 inch container. The rods were cut into sample blanks. The
sample blanks were heat treated to a T-6 condition by solution
treating at 900.degree. F. for 1 hour, room temperature water
quenched and then aged for 24 hours at 250.degree. F. Room
temperature tensile tests were conducted on specimens machined into
reduced section bars and the results are presented in Table 1. The
yield strength goal for the new alloy was set at 20% higher than
7050, or 85 ksi. The data indicate that all of the alloys have
yield strengths greater than 85.
TABLE-US-00001 TABLE 1 Strength Data for High Strength Aluminum
Alloys Ulti- Strain Material Ceramic Yield mate at Descrip- Content
Strength Strength Failure tion Mg Zn Cu (v %) (ksi) (ksi) (%) 7050*
1.6- 5.7- 2.0- -- 71 80 9 2.6 6.7 2.6 A 2.7 9.6 2 0 102.7 104 7.7 B
2.7 9.6 2 1 101.4 105 7.3 C 2.7 9.6 2 3 100 103 5 D 2.7 9.6 2 5 95
100 5 E 2.9 10.00 1.50 10 97.8 100.6 2.42 F 2.2 11.00 1.25 10 90.0
95.3 3.24 G 2 8.40 1.70 5 92.0 98.0 8.50 H 2.7 9.00 1.50 10 95.3
100.2 3.01 I 2.5 9.00 2.00 10 85.2 93.6 2.30 J 2.2 9.49 1.50 10
91.0 101.9 2.68 K 2.2 9.50 1.50 5 90.7 95.8 5.03 L 2.7 9.50 2.00 10
104.5 109.0 3.03 M 2.7 9.50 2.00 10 100.0 104.8 2.25 N 2.7 9.50
2.00 10 85.2 93.6 2.30 O 2.9 9.50 2.00 10 98.3 100.5 2.30 P 2.5
9.50 2.00 10 94.0 97.2 2.89 Q 2.9 9.50 2.00 10 95.8 100.4 2.98 *The
data for 7050 is from the Mil Handbook 7-G.
[0014] The chemical composition limits for alloys in accordance
with embodiments of this invention are defined in Table 2.
TABLE-US-00002 TABLE 2 Alloy Element Composition Limits Min Max Si
0.15 Fe 0.2 Cu 1.5 3.0 Mn -- Mg 2.5 3.5 Cr -- Ni -- Zn 9.0 10.3 Ti
Ga -- V -- Zr -- Oxygen 0.05 0.50 Others, Each 0.05 Others, Total
0.15
[0015] It will be recognized that the above-described invention may
be embodied in other specific forms without departing from the
spirit or essential characteristics of the disclosure. Thus, it is
understood that the invention is not to be limited by the foregoing
illustrative details, but rather is to be defined by the appended
claims.
* * * * *