ALUMINUM-COPPER-LITHIUM ALLOYS

• US 20090142222A1
• Filed: 12/04/2008
• Published: 06/04/2009
• Est. Priority Date: 12/04/2007
• Status: Active Grant

• Current Assignee: Arconic Technologies LLC (Arconic Corp.)
• Original Assignee: Alcoa Incorporated (Howmet Aerospace, Inc.)
• Inventors: Colvin, Edward L., Yocum, Les A., Wilson, Andre L., Cogswell, Todd K., Sawtell, Ralph R., Rioja, Roberto J., Denzer, Diana K., Bray, Gary H.
• Granted Patent: US 8,118,950 B2
• Time in Patent Office: Days
• US Class Current: 420/532
• CPC Class Codes: C22C 21/16 with magnesium
• CPC Class Codes: C22C 21/18 with zinc
• CPC Class Codes: C22F 1/057 of alloys with copper as the next major constituent

Abstract

Improved aluminum-copper-lithium alloys are disclosed. The alloys may include 3.4-4.2 wt. % Cu, 0.9-1.4 wt. % Li, 0.3-0.7 wt. % Ag, 0.1-0.6 wt. % Mg, 0.2-0.8 wt. % Zn, 0.1-0.6 wt. % Mn, and 0.01-0.6 wt. % of at least one grain structure control element, the balance being aluminum and incidental elements and impurities. The alloys achieve an improved combination of properties over prior art alloys.

Claims

1. An extruded aluminum alloy consisting essentially of:

3.4-4.2 wt. % Cu;

0.9-1.4 wt. % Li;

0.3-0.7 wt. % Ag;

0.1-0.6 wt. % Mg;

0.2-0.8 wt. % Zn;

0.1-0.6 wt. % Mn; and

0.01-0.6 wt. % of at least one grain structure control element;

the balance being aluminum and incidental elements and impurities.

2. The extruded aluminum alloy of claim 1, wherein the aluminum alloy realizes a longitudinal tensile yield strength of at least about 86 ksi.

3. The extruded aluminum alloy of claim 1, wherein the aluminum alloy realizes an L-T plane strain fracture toughness of at least about 20 ksi√

in.

4. The extruded aluminum alloy of claim 1, wherein the aluminum alloy is resistant to stress corrosion cracking.

5. The extruded aluminum alloy of claim 1, wherein the aluminum alloy achieves a MASTMAASIS rating of at least EA.

6. The extruded aluminum alloy of claim 1, wherein the aluminum alloy realizes a typical tension modulus of at least about 11.3×

10³ ksi and a typical compression modulus of at least about 11.6×

10³ ksi.

7. The extruded aluminum alloy of claim 1, wherein the aluminum alloy has a density of not greater than about 0.097 lbs./in³.

8. The extruded aluminum alloy of claim 1, wherein the aluminum alloy has a specific strength of at least about 8.66×

10⁵ in.

9. The extruded aluminum alloy of claim 1, wherein the aluminum alloy realizes a compressive yield strength of at least about 90 ksi.

10. The extruded alloy of claim 1, wherein the alloy has an accumulated cold work of not greater than an equivalent of 4% stretch.

11. The extruded alloy of claim 1, wherein the alloy comprises:

3.6-4.1 wt. % Cu;

1.0-1.3 wt. % Li;

0.3-0.7 wt. % Zn;

0.4-0.6 wt. % Ag;

0.2-0.5 wt. % Mg; and

0.1-0.4 wt. % Mn.

12. The extruded alloy of claim 1, wherein the alloy comprises:

3.7-4.0 wt. % Cu;

1.1-1.2 wt. % Li;

0.4-0.6 wt. % Zn;

0.4-0.6 wt. % Ag;

0.25-0.45 wt. % Mg; and

0.2-0.4 wt. % Mn.

13. The extruded alloy of claim 1, wherein the grain structure control element is Zr, and wherein the alloy includes 0.05-0.15 wt. % Zr.

14. The extruded alloy of claim 13, wherein the impurities comprises Fe and Si, and wherein the alloy comprises not greater than about 0.06 wt. % Si and not greater than about 0.08 wt. % Fe.

15. The extruded alloy of claim 1, wherein the alloy is resistant to galvanic corrosion.

16. An airplane stringer comprising the alloy of claim 1.

17. An airplane spar comprising the alloy of claim 1.

18. An aluminum alloy consisting essentially of:

3.4-4.2 wt. % Cu;

0.9-1.4 wt. % Li;

0.3-0.7 wt. % Ag;

0.1-0.6 wt. % Mg;

0.2-0.8 wt. % Zn;

0.1-0.6 wt. % Mn; and

0.01-0.6 wt. % of at least one grain structure control element;

the balance being aluminum and incidental elements and impurities;

wherein the aluminum alloy realizes a longitudinal strength of at least about 84 ksi, an L-T plane strain fracture toughness of at least about 20 ksi√

in, wherein the aluminum alloy is resistant to stress corrosion cracking and wherein the aluminum alloy is resistant to galvanic corrosion.

19. The aluminum alloy of claim 18, wherein the alloy is a wrought product.

20. The aluminum alloy of claim 19, wherein the wrought product is an extrusion, plate or sheet product.