U.S. patent application number 12/939345 was filed with the patent office on 2011-02-24 for heat treatable l12 aluminum alloys.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Awadh B. Pandey.
Application Number | 20110041963 12/939345 |
Document ID | / |
Family ID | 40671419 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041963 |
Kind Code |
A1 |
Pandey; Awadh B. |
February 24, 2011 |
HEAT TREATABLE L12 ALUMINUM ALLOYS
Abstract
A method of forming high temperature heat treatable aluminum
alloys that can be used at temperatures from about -420.degree. F.
(-251.degree. C.) up to about 650.degree. F. (343.degree. C.) are
described. The alloys are strengthened by dispersion of particles
based on the L1.sub.2 intermetallic compound Al.sub.3X. These
alloys comprise aluminum, copper, magnesium, at least one of
scandium, erbium, thulium, ytterbium, and lutetium; and at least
one of gadolinium, yttrium, zirconium, titanium, hafnium, and
niobium. Lithium is an optional alloying element.
Inventors: |
Pandey; Awadh B.; (Jupiter,
FL) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
THE KINNEY & LANGE BUILDING, 312 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415-1002
US
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
40671419 |
Appl. No.: |
12/939345 |
Filed: |
November 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12148396 |
Apr 18, 2008 |
|
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12939345 |
|
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Current U.S.
Class: |
148/550 ;
148/549 |
Current CPC
Class: |
C22C 21/16 20130101;
C22F 1/057 20130101 |
Class at
Publication: |
148/550 ;
148/549 |
International
Class: |
C22F 1/057 20060101
C22F001/057 |
Claims
1. A method of forming a heat treatable aluminum alloy, the method
comprising: (a) forming a melt consisting of: about 1.0 to about
8.0 weight percent copper; about 0.2 to about 4.0 weight percent
magnesium; about 0.5 to about 3.0 weight percent lithium; at least
one first element selected from the group comprising about 0.1 to
about 0.5 weight percent scandium, about 0.1 to about 6.0 weight
percent erbium, about 0.1 to about 10.0 weight percent thulium,
about 0.1 to about 15.0 weight percent ytterbium, and about 0.1 to
about 12.0 weight percent lutetium; at least one second element
selected from the group comprising about 0.1 to about 4.0 weight
percent gadolinium, about 0.1 to about 4.0 weight percent yttrium,
about 0.05 to about 1.0 weight percent zirconium, about 0.05 to
about 2.0 weight percent titanium, about 0.05 to about 2.0 weight
percent hafnium, and about 0.05 to about 1.0 weight percent
niobium; and the balance substantially aluminum; (b) solidifying
the melt to form a solid body; and (c) heat treating the solid
body.
2. The method of claim 1, further comprising: refining the
structure of the solid body by deformation processing comprising at
least one of: extrusion, forging and rolling.
3. The method of claim 1, wherein solidifying comprises a casting
process.
4. The method of claim 1, wherein solidifying comprises a rapid
solidification process in which the cooling rate is greater than
about 10.sup.3.degree. C./second and comprising at least one of:
powder processing, atomization, melt spinning, splat quenching,
spray deposition, cold spray, plasma spray, laser melting, laser
deposition, ball milling, and cryomilling.
5. The method of claim 1, wherein the heat treating comprises:
solution heat treatment at about 800.degree. F. (426.degree. C.) to
about 1100.degree. F. (593.degree. C.) for about thirty minutes to
four hours; quenching; and aging at about 200.degree. F.
(93.degree. C.) to about 600.degree. F. (316.degree. C.) for about
two to forty-eight hours.
6. A method of forming a heat treatable aluminum alloy, the method
comprising: (a) forming a melt consisting of: about 1.0 to about
8.0 weight percent copper; about 0.2 to about 4.0 weight percent
magnesium; about 0.5 to about 3.0 weight percent lithium; at least
one first element selected from the group comprising about 0.1 to
about 0.5 weight percent scandium, about 0.1 to about 6.0 weight
percent erbium, about 0.1 to about 10.0 weight percent thulium,
about 0.1 to about 15.0 weight percent ytterbium, and about 0.1 to
about 12.0 weight percent lutetium; at least one second element
selected from the group comprising about 0.1 to about 4.0 weight
percent gadolinium, about 0.1 to about 4.0 weight percent yttrium,
about 0.05 to about 1.0 weight percent zirconium, about 0.05 to
about 2.0 weight percent titanium, about 0.05 to about 2.0 weight
percent hafnium, and about 0.05 to about 1.0 weight percent
niobium; comprising no more than about 0.1 weight percent iron,
about 0.1 weight percent chromium, about 0.1 weight percent
manganese, about 0.1 weight percent vanadium, about 0.1 weight
percent cobalt, and about 0.1 weight percent nickel; no more than
about 1.0 weight percent total other additional elements not listed
therein including impurities; and the balance substantially
aluminum; (b) solidifying the melt to form a solid body; and (c)
heat treating the solid body.
7. The method of claim 6, further comprising: refining the
structure of the solid body by deformation processing comprising at
least one of: extrusion, forging and rolling.
8. The method of claim 6, wherein solidifying comprises a casting
process.
9. The method of claim 6, wherein solidifying comprises a rapid
solidification process in which the cooling rate is greater than
about 10.sup.3.degree. C./second and comprising at least one of:
powder processing, atomization, melt spinning, splat quenching,
spray deposition, cold spray, plasma spray, laser melting, laser
deposition, ball milling, and cryomilling.
10. The method of claim 6, wherein the heat treating comprises:
solution heat treatment at about 800.degree. F. (426.degree. C.) to
about 1100.degree. F. (593.degree. C.) for about thirty minutes to
four hours; quenching; and aging at about 200.degree. F.
(93.degree. C.) to about 600.degree. F. (316.degree. C.) for about
two to forty-eight hours.
11. A method of forming a heat treatable aluminum alloy, the method
comprising: (a) forming a melt consisting of: about 1.0 to about
8.0 weight percent copper; about 0.2 to about 4.0 weight percent
magnesium; about 0.5 to about 3.0 weight percent lithium; at least
one first element selected from the group comprising about 0.1 to
about 0.5 weight percent scandium, about 0.1 to about 6.0 weight
percent erbium, about 0.1 to about 10.0 weight percent thulium,
about 0.1 to about 15.0 weight percent ytterbium, and about 0.1 to
about 12.0 weight percent lutetium; at least one second element
selected from the group comprising about 0.1 to about 4.0 weight
percent gadolinium, about 0.1 to about 4.0 weight percent yttrium,
about 0.05 to about 1.0 weight percent zirconium, about 0.05 to
about 2.0 weight percent titanium, about 0.05 to about 2.0 weight
percent hafnium, and about 0.05 to about 1.0 weight percent
niobium; no more than about 1.0 weight percent total other
additional elements not listed therein including impurities; and
the balance substantially aluminum; (b) solidifying the melt to
form a solid body; and (c) heat treating the solid body.
12. The method of claim 11, further comprising: refining the
structure of the solid body by deformation processing comprising at
least one of: extrusion, forging and rolling.
13. The method of claim 11, wherein solidifying comprises a casting
process.
14. The method of claim 11, wherein solidifying comprises a rapid
solidification process in which the cooling rate is greater than
about 10.sup.3.degree. C./second and comprising at least one of:
powder processing, atomization, melt spinning, splat quenching,
spray deposition, cold spray, plasma spray, laser melting, laser
deposition, ball milling, and cryomilling.
15. The method of claim 11 wherein the heat treating comprises:
solution heat treatment at about 800.degree. F. (426.degree. C.) to
about 1100.degree. F. (593.degree. C.) for about thirty minutes to
four hours; quenching; and aging at about 200.degree. F.
(93.degree. C.) to about 600.degree. F. (316.degree. C.) for about
two to forty-eight hours.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/148,396, filed Apr. 18, 2008 for HEAT
TREATABLE L1.sub.2 ALUMINUM ALLOYS, now U.S. Pat. No. ______.
BACKGROUND
[0002] The present invention relates generally to aluminum alloys
and more specifically to heat treatable aluminum alloys produced by
melt processing and strengthened by L1.sub.2 phase dispersions.
[0003] The combination of high strength, ductility, and fracture
toughness, as well as low density, make aluminum alloys natural
candidates for aerospace and space applications. However, their use
is typically limited to temperatures below about 300.degree. F.
(149.degree. C.) since most aluminum alloys start to lose strength
in that temperature range as a result of coarsening of
strengthening precipitates.
[0004] The development of aluminum alloys with improved elevated
temperature mechanical properties is a continuing process. Some
attempts have included aluminum-iron and aluminum-chromium based
alloys such as Al--Fe--Ce, Al--Fe--V--Si, Al--Fe--Ce--W, and
Al--Cr--Zr--Mn that contain incoherent dispersoids. These alloys,
however, also lose strength at elevated temperatures due to
particle coarsening. In addition, these alloys exhibit ductility
and fracture toughness values lower than other commercially
available aluminum alloys.
[0005] Other attempts have included the development of mechanically
alloyed Al--Mg and Al--Ti alloys containing ceramic dispersoids.
These alloys exhibit improved high temperature strength due to the
particle dispersion, but the ductility and fracture toughness are
not improved.
[0006] U.S. Pat. No. 6,248,453 discloses aluminum alloys
strengthened by dispersed Al.sub.3X L1.sub.2 intermetallic phases
where X is selected from the group consisting of Sc, Er, Lu, Yb,
Tm, and U. The Al.sub.3X particles are coherent with the aluminum
alloy matrix and are resistant to coarsening at elevated
temperatures. The improved mechanical properties of the disclosed
dispersion strengthened L1.sub.2 aluminum alloys are stable up to
572.degree. F. (300.degree. C.). In order to create aluminum alloys
containing fine dispersions of Al.sub.3X L1.sub.2 particles, the
alloys need to be manufactured by expensive rapid solidification
processes with cooling rates in excess of 1.8.times.10.sup.3 F/sec
(10.sup.3.degree. C./sec). U.S. Patent Application Publication No.
2006/0269437 A1 discloses an aluminum alloy that contains scandium
and other elements. While the alloy is effective at high
temperatures, it is not capable of being heat treated using a
conventional age hardening mechanism.
[0007] Heat treatable aluminum alloys strengthened by coherent
L1.sub.2 intermetallic phases produced by standard, inexpensive
melt processing techniques would be useful.
SUMMARY
[0008] The present invention is heat treatable aluminum alloys that
can be cast, wrought, or formed by rapid solidification, and
thereafter heat treated. The alloys can achieve high temperature
performance and can be used at temperatures up to about 650.degree.
F. (343.degree. C.).
[0009] These alloys comprise copper, magnesium, lithium and an
Al.sub.3X L1.sub.2 dispersoid where X is at least one first element
selected from scandium, erbium, thulium, ytterbium, and lutetium,
and at least one second element selected from gadolinium, yttrium,
zirconium, titanium, hafnium, and niobium. The balance is
substantially aluminum.
[0010] The alloys have less than about 1.0 weight percent total
impurities.
[0011] The alloys are formed by a process selected from casting,
deformation processing and rapid solidification. The alloys are
then heat treated at a temperature of from about 900.degree. F.
(482.degree. C.) to about 1100.degree. F. (593.degree. C.) for
between about 30 minutes and four hours, followed by quenching in
water, and thereafter aged at a temperature from about 200.degree.
F. (93.degree. C.) to about 600.degree. F. (315.degree. C.) for
about two to about forty-eight hours.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an aluminum copper phase diagram.
[0013] FIG. 2 is an aluminum magnesium phase diagram.
[0014] FIG. 3 is an aluminum lithium phase diagram.
[0015] FIG. 4 is an aluminum scandium phase diagram.
[0016] FIG. 5 is an aluminum erbium phase diagram.
[0017] FIG. 6 is an aluminum thulium phase diagram.
[0018] FIG. 7 is an aluminum ytterbium phase diagram.
[0019] FIG. 8 is an aluminum lutetium phase diagram.
DETAILED DESCRIPTION
[0020] The alloys of this invention are based on the aluminum,
copper, magnesium, lithium system. The amount of copper in these
alloys ranges from about 1.0 to about 8.0 weight percent, more
preferably about 2.0 to about 7.0 weight percent, and even more
preferably about 3.5 to about 6.5 weight percent. The amount of
magnesium in these alloys ranges from about 0.2 to about 4.0 weight
percent, more preferably about 0.4 to about 3.0 weight percent, and
even more preferably about 0.5 to about 2.0 weight percent. The
amount of lithium in these alloys ranges from about 0.5 to about
3.0 weight percent, more preferably about 1.0 to about 2.5 weight
percent, and even more preferably about 1.0 to about 2.0 weight
percent.
[0021] Copper, magnesium and lithium are completely soluble in the
composition of the inventive alloys discussed herein. Aluminum
magnesium lithium alloys are heat treatable with L1.sub.2
Al.sub.3Li (.delta.'), Al.sub.2LiMg, Al.sub.2CuMg (S') and
Al.sub.2CuLi precipitating following a solution heat treatment,
quench and age process. These phases precipitate as coherent second
phases in the aluminum magnesium lithium solid solution matrix.
Also, in the solid solutions are dispersions of Al.sub.3X having an
L1.sub.2 structure where X is at least one first element selected
from scandium, erbium, thulium, ytterbium, and lutetium and at
least one second element selected from gadolinium, yttrium,
zirconium, titanium, hafnium, and niobium.
[0022] The aluminum copper phase diagram is shown in FIG. 1. The
aluminum copper binary system is a eutectic alloy system with a
eutectic reaction at 31.2 weight percent magnesium and 1018.degree.
F. (548.2.degree. C.). Copper has maximum solid solubility of 6
weight percent in aluminum at 1018.degree. F. (548.2.degree. C.)
which can be extended further by rapid solidification processing.
Copper provides a considerable amount of precipitation
strengthening in aluminum by precipitation of fine second phases.
The present invention is focused on hypoeutectic alloy composition
ranges.
[0023] The aluminum magnesium phase diagram is shown in FIG. 2. The
binary system is a eutectic alloy system with a eutectic reaction
at 36 weight percent magnesium and 842.degree. F. (450.degree. C.).
Magnesium has maximum solid solubility of 16 weight percent in
aluminum at 842.degree. F. (450.degree. C.) which can be extended
further by rapid solidification processing. Magnesium provides
substantial solid solution strengthening in aluminum. In addition,
magnesium provides precipitation strengthening through
precipitation of Al.sub.2CuMg (S') phase in the presence of
copper.
[0024] The aluminum lithium phase diagram is shown in FIG. 3. The
binary system is a eutectic alloy system with a eutectic reaction
at 8 weight percent magnesium and 1104.degree. F. (596.degree. C.).
Lithium has maximum solid solubility of about 4.5 weight percent in
aluminum at 1104.degree. F. (596.degree. C.). Lithium has lesser
solubility in aluminum in the presence of magnesium compared to
when magnesium is absent. Therefore, lithium provides significant
precipitation strengthening through precipitation of Al.sub.3Li
(.delta.') phase. Lithium in addition provides reduced density and
increased modulus in aluminum. In the presence of magnesium and
copper, lithium forms ternary precipitates based on Al.sub.2CuLi
and Al.sub.2MgLi.
[0025] The alloys of this invention contain phases consisting of
primary aluminum, aluminum copper solid solutions, aluminum
magnesium solid solutions, and aluminum lithium solid solutions. In
the solid solutions are dispersions of Al.sub.3X having an L1.sub.2
structure where X is at least one element selected from scandium,
erbium, thulium, ytterbium, and lutetium. Also present is at least
one element selected from gadolinium, yttrium, zirconium, titanium,
hafnium, and niobium.
[0026] Exemplary aluminum alloys of this invention include, but are
not limited to (in weight percent):
[0027]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.1-4.0)Gd;
[0028] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-6)Er-(0.1-4.0)Gd;
[0029] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.1-4.0)Gd;
[0030] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.1-4.0)Gd;
[0031] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-12)Lu-(0.1-4.0)Gd;
[0032] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.1-4.0)Y;
[0033] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-6)Er-(0.1-4.0)Y;
[0034] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.1-4.0)Y;
[0035] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.1-4.0)Y;
[0036] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-12)Lu-(0.1-4.0)Y;
[0037]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.05-1.0)Zr;
[0038] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-6)Er-(0.05-1.0)Zr;
[0039]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.05-1.0)Zr;
[0040]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.05-1.0)Zr;
[0041]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-12)Lu-(0.05-1.0)Zr;
[0042]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.05-2.0)Ti;
[0043]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Er-(0.05-2.0)Ti;
[0044]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.05-2.0)Ti;
[0045]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.05-2.0)Ti;
[0046]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-4)-Lu-(0.05-2.0)Ti;
[0047]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.05-2.0)Hf;
[0048] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-6)Er-(0.05-2.0)Hf;
[0049]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.05-2.0)Hf;
[0050]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.05-2.0)Hf;
[0051]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-12)Lu-(0.05-2.0)Hf;
[0052]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-0.5)Sc-(0.05-1.0)Nb;
[0053] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-6)Er-(0.05-1.0)Nb;
[0054]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-10)Tm-(0.05-1.0)Nb;
[0055] Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-15)Yb-(0.05-1.0)Nb;
and
[0056]
Al-(1-8)Cu-(0.2-4)Mg-(0.5-3.0)Li-(0.1-12)Lu-(0.05-1.0)Nb.
[0057] Preferred examples of similar alloys to these are alloys
with about 2.0 to about 7.0 weight percent copper, alloys with
about 0.4 to about 3.0 weight percent magnesium, and alloys with
about 1.0 to about 2.5 weight percent lithium.
[0058] In the inventive aluminum based alloys disclosed herein,
scandium, erbium, thulium, ytterbium, and lutetium are potent
strengtheners that have low diffusivity and low solubility in
aluminum. All these element form equilibrium Al.sub.3X
intermetallic dispersoids where X is at least one of scandium,
erbium, ytterbium, lutetium, that have an L1.sub.2 structure that
is an ordered face centered cubic structure with the X atoms
located at the corners and aluminum atoms located on the cube faces
of the unit cell.
[0059] Scandium forms Al.sub.3Sc dispersoids that are fine and
coherent with the aluminum matrix. Lattice parameters of aluminum
and Al.sub.3Sc are very close (0.405 nm and 0.410 nm respectively),
indicating that there is minimal or no driving force for causing
growth of the Al.sub.3Sc dispersoids. This low interfacial energy
makes the Al.sub.3Sc dispersoids thermally stable and resistant to
coarsening up to temperatures as high as about 842.degree. F.
(450.degree. C.). In the alloys of this invention these Al.sub.3Sc
dispersoids are made stronger and more resistant to coarsening at
elevated temperatures by adding suitable alloying elements such as
gadolinium, yttrium, zirconium, titanium, hafnium, niobium, or
combinations thereof, that enter Al.sub.3Sc in solution.
[0060] Erbium forms Al.sub.3Er dispersoids in the aluminum matrix
that are fine and coherent with the aluminum matrix. The lattice
parameters of aluminum and Al.sub.3Er are close (0.405 nm and 0.417
nm respectively), indicating there is minimal driving force for
causing growth of the Al.sub.3Er dispersoids. This low interfacial
energy makes the Al.sub.3Er dispersoids thermally stable and
resistant to coarsening up to temperatures as high as about
842.degree. F. (450.degree. C.). Additions of magnesium in solid
solution in aluminum increase the lattice parameter of the aluminum
matrix, and decrease the lattice parameter mismatch further
increasing the resistance of the Al.sub.3Er to coarsening.
Additions of copper increase the strength of alloys through
precipitation of Al.sub.2Cu (.theta.') and Al.sub.2CuMg (S')
phases. In the alloys of this invention, these Al.sub.3Er
dispersoids are made stronger and more resistant to coarsening at
elevated temperatures by adding suitable alloying elements such as
gadolinium, yttrium, zirconium, titanium, hafnium, niobium, or
combinations thereof that enter Al.sub.3Er in solution.
[0061] Thulium forms metastable Al.sub.3Tm dispersoids in the
aluminum matrix that are fine and coherent with the aluminum
matrix. The lattice parameters of aluminum and Al.sub.3Tm are close
(0.405 nm and 0.420 nm respectively), indicating there is minimal
driving force for causing growth of the Al.sub.3Tm dispersoids.
This low interfacial energy makes the Al.sub.3Tm dispersoids
thermally stable and resistant to coarsening up to temperatures as
high as about 842.degree. F. (450.degree. C.). Additions of
magnesium in solid solution in aluminum increase the lattice
parameter of the aluminum matrix, and decrease the lattice
parameter mismatch further increasing the resistance of the
Al.sub.3Tm to coarsening. Additions of copper increase the strength
of alloys through precipitation of Al.sub.2Cu (.theta.') and
Al.sub.2CuMg (S') phases. In the alloys of this invention these
Al.sub.3Tm dispersoids are made stronger and more resistant to
coarsening at elevated temperatures by adding suitable alloying
elements such as gadolinium, yttrium, zirconium, titanium, hafnium,
niobium, or combinations thereof that enter Al.sub.3Tm in
solution.
[0062] Ytterbium forms Al.sub.3Yb dispersoids in the aluminum
matrix that are fine and coherent with the aluminum matrix. The
lattice parameters of Al and Al.sub.3Yb are close (0.405 nm and
0.420 nm respectively), indicating there is minimal driving force
for causing growth of the Al.sub.3Yb dispersoids. This low
interfacial energy makes the Al.sub.3Yb dispersoids thermally
stable and resistant to coarsening up to temperatures as high as
about 842.degree. F. (450.degree. C.). Additions of magnesium in
solid solution in aluminum increase the lattice parameter of the
aluminum matrix, and decrease the lattice parameter mismatch
further increasing the resistance of the Al.sub.3Yb to coarsening.
Additions of copper increase the strength of alloys through
precipitation of Al.sub.2Cu (.theta.') and Al.sub.2CuMg (S')
phases. In the alloys of this invention, these Al.sub.3Yb
dispersoids are made stronger and more resistant to coarsening at
elevated temperatures by adding suitable alloying elements such as
gadolinium, yttrium, zirconium, titanium, hafnium, niobium, or
combinations thereof that enter Al.sub.3Yb in solution.
[0063] Lutetium forms Al.sub.3Lu dispersoids in the aluminum matrix
that are fine and coherent with the aluminum matrix. The lattice
parameters of Al and Al.sub.3Lu are close (0.405 nm and 0.419 nm
respectively), indicating there is minimal driving force for
causing growth of the Al.sub.3Lu dispersoids. This low interfacial
energy makes the Al.sub.3Lu dispersoids thermally stable and
resistant to coarsening up to temperatures as high as about
842.degree. F. (450.degree. C.). Additions of magnesium in solid
solution in aluminum increase the lattice parameter of the aluminum
matrix, and decrease the lattice parameter mismatch further
increasing the resistance of the Al.sub.3Lu to coarsening Additions
of copper increase the strength of alloys through precipitation of
Al.sub.2Cu (.theta.') and Al.sub.2CuMg (S') phases. In the alloys
of this invention, these Al.sub.3Lu dispersoids are made stronger
and more resistant to coarsening at elevated temperatures by adding
suitable alloying elements such as gadolinium, yttrium, zirconium,
titanium, hafnium, niobium, or mixtures thereof that enter
Al.sub.3Lu in solution.
[0064] Gadolinium forms metastable Al.sub.3Gd dispersoids in the
aluminum matrix that are stable up to temperatures as high as about
842.degree. F. (450.degree. C.) due to their low diffusivity in
aluminum. The Al.sub.3Gd dispersoids have a D0.sub.19 structure in
the equilibrium condition. Despite its large atomic size,
gadolinium has fairly high solubility in the Al.sub.3X
intermetallic dispersoids (where X is scandium, erbium, thulium,
ytterbium or lutetium). Gadolinium can substitute for the X atoms
in Al.sub.3X intermetallic, thereby forming an ordered L1.sub.2
phase which results in improved thermal and structural
stability.
[0065] Yttrium forms metastable Al.sub.3Y dispersoids in the
aluminum matrix that have an L1.sub.2 structure in the metastable
condition and a D0.sub.19 structure in the equilibrium condition.
The metastable Al.sub.3Y dispersoids have a low diffusion
coefficient which makes them thermally stable and highly resistant
to coarsening. Yttrium has a high solubility in the Al.sub.3X
intermetallic dispersoids allowing large amounts of yttrium to
substitute for X in the Al.sub.3X L1.sub.2 dispersoids which
results in improved thermal and structural stability.
[0066] Zirconium forms Al.sub.3Zr dispersoids in the aluminum
matrix that have an L1.sub.2 structure in the metastable condition
and D0.sub.23 structure in the equilibrium condition. The
metastable Al.sub.3Zr dispersoids have a low diffusion coefficient
which makes them thermally stable and highly resistant to
coarsening. Zirconium has a high solubility in the Al.sub.3X
dispersoids allowing large amounts of zirconium to substitute for X
in the Al.sub.3X dispersoids, which results in improved thermal and
structural stability.
[0067] Titanium forms Al.sub.3Ti dispersoids in the aluminum matrix
that have an L1.sub.2 structure in the metastable condition and
DO.sub.22 structure in the equilibrium condition. The metastable
Al.sub.3Ti despersoids have a low diffusion coefficient which makes
them thermally stable and highly resistant to coarsening. Titanium
has a high solubility in the Al.sub.3X dispersoids allowing large
amounts of titanium to substitute for X in the Al.sub.3X
dispersoids, which result in improved thermal and structural
stability.
[0068] Hafnium forms metastable Al.sub.3Hf dispersoids in the
aluminum matrix that have an L1.sub.2 structure in the metastable
condition and a D0.sub.23 structure in the equilibrium condition.
The Al.sub.3Hf dispersoids have a low diffusion coefficient, which
makes them thermally stable and highly resistant to coarsening.
Hafnium has a high solubility in the Al.sub.3X dispersoids allowing
large amounts of hafnium to substitute for scandium, erbium,
thulium, ytterbium, and lutetium in the above mentioned Al.sub.3X
dispersoides, which results in stronger and more thermally stable
dispersoids.
[0069] Niobium forms metastable Al.sub.3Nb dispersoids in the
aluminum matrix that have an L1.sub.2 structure in the metastable
condition and a D0.sub.22 structure in the equilibrium condition.
Niobium has a lower solubility in the Al.sub.3X dispersoids than
hafnium or yttrium, allowing relatively lower amounts of niobium
than hafnium or yttrium to substitute for X in the Al.sub.3X
dispersoids. Nonetheless, niobium can be very effective in slowing
down the coarsening kinetics of the Al.sub.3X dispersoids because
the Al.sub.3Nb dispersoids are thermally stable. The substitution
of niobium for X in the above mentioned Al.sub.3X dispersoids
results in stronger and more thermally stable dispersoids.
[0070] Al.sub.3X L1.sub.2 precipitates improve elevated temperature
mechanical properties in aluminum alloys for two reasons. First,
the precipitates are ordered intermetallic compounds. As a result,
when the particles are sheared by glide dislocations during
deformation, the dislocations separate into two partial
dislocations separated by an anti-phase boundary on the glide
plane. The energy to create the anti-phase boundary is the origin
of the strengthening. Second, the cubic L1.sub.2 crystal structure
and lattice parameter of the precipitates are closely matched to
the aluminum solid solution matrix. This results in a lattice
coherency at the precipitate/matrix boundary that resists
coarsening. The lack of an interphase boundary results in a low
driving force for particle growth and resulting elevated
temperature stability. Alloying elements in solid solution in the
dispersed strengthening particles and in the aluminum matrix that
tend to decrease the lattice mismatch between the matrix and
particles will tend to increase the strengthening and elevated
temperature stability of the alloy.
[0071] Copper has considerable solubility in aluminum at
1018.degree. F. (548.2.degree. C.), which decreases with a decrease
in temperature. The aluminum copper alloy system provides
considerable precipitation hardening response through precipitation
of Al.sub.2Cu (.theta.') second phase. Magnesium has considerable
solubility in aluminum at 842.degree. F. (450.degree. C.) which
decreases with a decrease in temperature. The aluminum magnesium
binary alloy system does not provide precipitation hardening,
rather it provides substantial solid solution strengthening. When
magnesium is added to aluminum copper alloy, it increases the
precipitation hardening response of the alloy considerably through
precipitation of Al.sub.2CuMg (S') phase. When the ratio of copper
to magnesium is high, precipitation hardening occurs through
precipitation of GP zones through coherent metastable Al.sub.2Cu
(.theta.') to equilibrium Al.sub.2Cu (.theta.) phase. When the
ratio of copper to magnesium is low, precipitation hardening occurs
through precipitation of GP zones through coherent metastable
Al.sub.2CuMg (S') to equilibrium Al.sub.2CuMg (S) phase. Lithium
provides considerable strengthening through precipitation of
coherent Al.sub.3Li (.delta.') phase. Lithium also forms
Al.sub.2MgLi and Al.sub.2CuLi phases which provide additional
strengthening when precipitated in desired size and shape. In
addition, lithium reduces density and increases modulus of the
aluminum alloys due to its lower density and higher modulus.
[0072] The amount of scandium present in the alloys of this
invention if any may vary from about 0.1 to about 0.5 weight
percent, more preferably from about 0.1 to about 0.35 weight
percent, and even more preferably from about 0.1 to about 0.25
weight percent. The Al--Sc phase diagram shown in FIG. 4 indicates
a eutectic reaction at about 0.5 weight percent scandium at about
1219.degree. F. (659.degree. C.) resulting in a solid solution of
scandium and aluminum and Al.sub.3Sc dispersoids. Aluminum alloys
with less than 0.5 weight percent scandium can be quenched from the
melt to retain scandium in solid solution that may precipitate as
dispersed L1.sub.2 intermetallic Al.sub.3Sc following an aging
treatment. Alloys with scandium in excess of the eutectic
composition (hypereutectic alloys) can only retain scandium in
solid solution by rapid solidification processing (RSP) where
cooling rates are in excess of about 10.sup.3.degree. C./second.
Alloys with scandium in excess of the eutectic composition cooled
normally will have a microstructure consisting of relatively large
Al.sub.3Sc dispersoids in a finally divided aluminum-Al.sub.3Sc
eutectic phase matrix.
[0073] The amount of erbium present in the alloys of this
invention, if any, may vary from about 0.1 to about 6.0 weight
percent, more preferably from about 0.1 to about 4.0 weight
percent, and even more preferably from about 0.2 to about 2.0
weight percent. The Al--Er phase diagram shown in FIG. 5 indicates
a eutectic reaction at about 6 weight percent erbium at about
1211.degree. F. (655.degree. C.). Aluminum alloys with less than
about 6 weight percent erbium can be quenched from the melt to
retain erbium in solid solutions that may precipitate as dispersed
L1.sub.2 intermetallic Al.sub.3Er following an aging treatment.
Alloys with erbium in excess of the eutectic composition can only
retain erbium in solid solution by rapid solidification processing
(RSP) where cooling rates are in excess of about 10.sup.3.degree.
C./second. Alloys with erbium in excess of the eutectic composition
(hypereutectic alloys) cooled normally will have a microstructure
consisting of relatively large Al.sub.3Er dispersoids in a finely
divided aluminum-Al.sub.3Er eutectic phase matrix.
[0074] The amount of thulium present in the alloys of this
invention, if any, may vary from about 0.1 to about 10.0 weight
percent, more preferably from about 0.2 to about 6.0 weight
percent, and even more preferably from about 0.2 to about 4.0
weight percent. The Al--Tm phase diagram shown in FIG. 6 indicates
a eutectic reaction at about 10 weight percent thulium at about
1193.degree. F. (645.degree. C.). Thulium forms Al.sub.3Tm
dispersoids in the aluminum matrix that have an L1.sub.2 structure
in the equilibrium condition. The Al.sub.3Tm dispersoids have a low
diffusion coefficient which makes them thermally stable and highly
resistant to coarsening. Aluminum alloys with less than 10 weight
percent thulium can be quenched from the melt to retain thulium in
solid solution that may precipitate as dispersed metastable
L1.sub.2 intermetallic Al.sub.3Tm following an aging treatment.
Alloys with thulium in excess of the eutectic composition can only
retain Tm in solid solution by rapid solidification processing
(RSP) where cooling rates are in excess of about 10.sup.3.degree.
C./second.
[0075] The amount of ytterbium present in the alloys of this
invention, if any, may vary from about 0.1 to about 15.0 weight
percent, more preferably from about 0.2 to about 8.0 weight
percent, and even more preferably from about 0.2 to about 4.0
weight percent. The Al--Yb phase diagram shown in FIG. 7 indicates
a eutectic reaction at about 21 weight percent ytterbium at about
1157.degree. F. (625.degree. C.). Aluminum alloys with less than
about 21 weight percent ytterbium can be quenched from the melt to
retain ytterbium in solid solution that may precipitate as
dispersed L1.sub.2 intermetallic Al.sub.3Yb following an aging
treatment. Alloys with ytterbium in excess of the eutectic
composition can only retain ytterbium in solid solution by rapid
solidification processing (RSP) where cooling rates are in excess
of about 10.sup.3.degree. C. per second. Alloys with ytterbium in
excess of the eutectic composition cooled normally will have a
microstructure consisting of relatively large Al.sub.3Yb
dispersoids in a finally divided aluminum-Al.sub.3Yb eutectic phase
matrix.
[0076] The amount of lutetium present in the alloys of this
invention, if any, may vary from about 0.1 to about 12.0 weight
percent, more preferably from about 0.2 to about 8.0 weight
percent, and even more preferably from about 0.2 to about 4.0
weight percent. The Al--Lu phase diagram shown in FIG. 8 indicates
a eutectic reaction at about 11.7 weight percent Lu at about
1202.degree. F. (650.degree. C.). Aluminum alloys with less than
about 11.7 weight percent lutetium can be quenched from the melt to
retain Lu in solid solution that may precipitate as dispersed
L1.sub.2 intermetallic Al.sub.3Lu following an aging treatment.
Alloys with Lu in excess of the eutectic composition can only
retain Lu in solid solution by rapid solidification processing
(RSP) where cooling rates are in excess of about 10.sup.3.degree.
C./second. Alloys with lutetium in excess of the eutectic
composition cooled normally will have a microstructure consisting
of relatively large Al.sub.3Lu dispersoids in a finely divided
aluminum-Al.sub.3Lu eutectic phase matrix.
[0077] The amount of gadolinium present in the alloys of this
invention, if any, may vary from about 0.1 to about 4 weight
percent, more preferably from 0.2 to about 2 weight percent, and
even more preferably from about 0.5 to about 2 weight percent.
[0078] The amount of yttrium present in the alloys of this
invention, if any, may vary from about 0.1 to about 4 weight
percent, more preferably from 0.2 to about 2 weight percent, and
even more preferably from about 0.5 to about 2 weight percent.
[0079] The amount of zirconium present in the alloys of this
invention, if any, may vary from about 0.05 to about 1 weight
percent, more preferably from 0.1 to about 0.75 weight percent, and
even more preferably from about 0.1 to about 0.5 weight
percent.
[0080] The amount of titanium present in the alloys of this
invention, if any, may vary from about 0.05 to about 2 weight
percent, more preferably from 0.1 to about 1 weight percent, and
even more preferably from about 0.1 to about 0.5 weight
percent.
[0081] The amount of hafnium present in the alloys of this
invention, if any, may vary from about 0.05 to about 2 weight
percent, more preferably from about 0.1 to about 1 weight percent,
and even more preferably from about 0.1 to about 0.5 weight
percent.
[0082] The amount of niobium present in the alloys of this
invention, if any, may vary from about 0.05 to about 1 weight
percent, more preferably from about 0.1 to about 0.75 weight
percent, and even more preferably from about 0.1 to about 0.5
weight percent.
[0083] In order to have the best properties for the alloys of this
invention, it is desirable to limit the amount of other elements.
Specific elements that should be reduced or eliminated include no
more than about 0.1 weight percent iron, about 0.1 weight percent
chromium, about 0.1 weight percent manganese, about 0.1 weight
percent vanadium, about 0.1 weight percent cobalt, and about 0.1
weight percent nickel. The total quantity of additional elements
should not exceed about 1% by weight, including the above listed
impurities and other elements.
[0084] Other additions in the alloys of this invention include at
least one of about 0.001 weight percent to about 0.10 weight
percent sodium, about 0.001 weight percent to about 0.10 weight
calcium, about 0.001 weight percent to about 0.10 weight percent
strontium, about 0.001 weight percent to about 0.10 weight percent
antimony, about 0.001 weight percent to about 0.10 weight percent
barium and about 0.001 weight percent to about 0.10 weight percent
phosphorus. These are added to refine the microstructure of the
eutectic phase and the primary magnesium or lithium morphology and
size.
[0085] These aluminum alloys may be made by any and all
consolidation and fabrication processes known to those in the art
such as casting (without further deformation), deformation
processing (wrought processing), rapid solidification processing,
forging, extrusion, rolling, die forging, powder metallurgy and
others. The rapid solidification process should have a cooling rate
greater that about 10.sup.3.degree. C./second including but not
limited to powder processing, atomization, melt spinning, splat
quenching, spray deposition, cold spray, plasma spray, laser
melting and deposition, ball milling and cryomilling.
[0086] Additional exemplary aluminum alloys of this invention
include, but are not limited to (in weight percent):
[0087] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.2-2.0)Gd;
[0088] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)Er-(0.2-2.0)Gd;
[0089] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.2-2.0)Gd;
[0090] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.2-2.0)Gd;
[0091] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Lu-(0.2-2.0)Gd;
[0092] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.2-2.0)Y;
[0093] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)Er-(0.2-2.0)Y;
[0094] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.2-2.0)Y;
[0095] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.2-2.0)Y;
[0096] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Lu-(0.2-2.0)Y;
[0097] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.1-0.75)Zr;
[0098] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)Er-(0.1-0.75)Zr;
[0099] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.1-0.75)Zr;
[0100] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.1-0.75)Zr;
[0101] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Lu-(0.1-0.75)Zr;
[0102] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.1-1.0)Ti;
[0103] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.5)Er-(0.1-1.0)Ti;
[0104] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.1-1.0)Ti;
[0105] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.1-1.0)Ti;
[0106] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)-Lu-(0.1-1.0)Ti;
[0107] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.1-1.0)Hf;
[0108] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)Er-(0.1-1.0)Hf;
[0109] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.1-1.0)Hf;
[0110] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.1-1.0)Hf;
[0111] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Lu-(0.1-1.0)Hf;
[0112] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-0.35)Sc-(0.1-0.75)Nb;
[0113] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.1-4)Er-(0.1-0.75)Nb;
[0114] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-6)Tm-(0.1-0.75)Nb;
[0115] about Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Yb-(0.1-0.75)Nb;
and
[0116] about
Al-(2-7)Cu-(0.4-3)Mg-(1-2.5)Li-(0.2-8)Lu-(0.1-0.75)Nb.
[0117] Preferred examples of similar alloys to these are alloys
with about 3.5 to about 6.5 weight percent copper, alloys with
about 0.5 to about 2.0 weight percent magnesium, and alloys with
about 1.0 to about 2.0 weight percent lithium.
[0118] Even more preferred exemplary aluminum alloys of this
invention include, but are not limited to (in weight percent):
[0119] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.2-2.0)Gd;
[0120] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-2)Er-(0.2-2.0)Gd;
[0121] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.2-2.0)Gd;
[0122] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.2-2.0)Gd;
[0123] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Lu-(0.2-2.0)Gd;
[0124] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.5-2.0)Y;
[0125] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-2)Er-(0.5-2.0)Y;
[0126] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.5-2.0)Y;
[0127] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.5-2.0)Y;
[0128] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Lu-(0.5-2.0)Y;
[0129] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.1-0.5)Zr;
[0130] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-2)Er-(0.1-0.5)Zr;
[0131] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.1-0.5)Zr;
[0132] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.1-0.5)Zr;
[0133] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Lu-(0.1-0.5)Zr;
[0134] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.1-0.5)Ti;
[0135] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.5)Er-(0.1-0.5)Ti;
[0136] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.1-0.5)Ti;
[0137] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.1-0.5)Ti;
[0138] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-4)-Lu-(0.1-0.5)Ti;
[0139] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.1-0.5)Hf;
[0140] about
Al-(-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-2)Er-(0.1-0.5)Hf;
[0141] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.1-0.5)Hf;
[0142] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.1-0.5)Hf;
[0143] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Lu-(0.1-0.5)Hf;
[0144] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.1-0.25)Sc-(0.1-0.5)Nb;
[0145] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-2)Er-(0.1-0.5)Nb;
[0146] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Tm-(0.1-0.5)Nb;
[0147] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Yb-(0.1-0.5)Nb; and
[0148] about
Al-(3.5-6.5)Cu-(0.5-2)Mg-(1-2)Li-(0.2-4)Lu-(0.1-0.5)Nb.
[0149] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *