Creep resistant titanium alloys

1. A titanium alloy consisting of, in weight percentages based on total alloy weight:

5.5 to 6.5 aluminum;

1.5 to 2.5 tin;

1.3 to 2.3 molybdenum;

0.1 to 10.0 zirconium;

0.01 to 0.30 silicon;

0.1 to 2.0 germanium;

0 to 0.30 oxygen;

0 to 0.30 iron;

0 to 0.05 nitrogen;

0 to 0.05 carbon;

0 to 0.015 hydrogen;

0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper;

titanium; and

impurities.

2. The titanium alloy of claim 1 consisting of, in weight percentages based on total alloy weight:

5.5 to 6.5 aluminum;

1.7 to 2.1 tin;

1.7 to 2.1 molybdenum;

3.4 to 4.4 zirconium;

0.03 to 0.11 silicon;

0.1 to 0.4 germanium;

0 to 0.30 oxygen;

0 to 0.30 iron;

0 to 0.05 nitrogen;

0 to 0.05 carbon;

0 to 0.015 hydrogen;

0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper;

titanium; and

impurities.

3. The titanium alloy of claim 1 consisting of, in weight percentages based on total alloy weight:

5.9 to 6.0 aluminum;

1.9 to 2.0 tin;

1.8 to 1.9 molybdenum;

3.5 to 4.3 zirconium;

0.06 to 0.11 silicon;

0.1 to 0.4 germanium;

0 to 0.30 oxygen;

0 to 0.30 iron;

0 to 0.05 nitrogen;

0 to 0.05 carbon;

0 to 0.015 hydrogen;

0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper;

titanium; and

impurities.

4. The titanium alloy of claim 1 , wherein the titanium alloy exhibits a steady-state creep rate less than 8×10 −4 (24 hrs) −1 at a temperature of at least 890° F. under a load of 52 ksi.

5. A method of making a titanium alloy, the method comprising:

solution treating a titanium alloy at 1780° F. to 1800° F. for 4 hours;

cooling the titanium alloy to ambient temperature at a rate depending on a cross-sectional thickness of the titanium alloy;

aging the titanium alloy at 1025° F. to 1125° F. for 8 hours; and

air cooling the titanium alloy,

wherein the titanium alloy has the composition recited in claim 1 .

6. The titanium alloy of claim 1 , wherein the titanium alloy exhibits an ultimate tensile strength of at least 130 ksi at 900° F.

7. A titanium alloy consisting essentially of, in weight percentages based on total alloy weight:

5.5 to 6.5 aluminum;

1.5 to 2.5 tin;

1.3 to 2.3 molybdenum;

0.1 to 10.0 zirconium;

0.01 to 0.30 silicon;

0.1 to 2.0 germanium;

titanium; and

impurities.

8. The titanium alloy of claim 7 , wherein an aluminum content in the alloy is, in weight percentages based on total alloy weight, 5.9 to 6.0.

9. The titanium alloy of claim 7 , wherein a tin content in the alloy is, in weight percentages based on total alloy weight, 1.7 to 2.1.

10. The titanium alloy of claim 7 , wherein a tin content in the alloy is, in weight percentages based on total alloy weight, 1.9 to 2.0.

11. The titanium alloy of claim 6 , wherein a molybdenum content in the alloy is, in weight percentages based on total alloy weight, 1.7 to 2.1.

12. The titanium alloy of claim 6 , wherein a molybdenum content in the alloy is, in weight percentages based on total alloy weight, 1.8 to 1.9.

13. The titanium alloy of claim 6 , wherein a zirconium content in the alloy is, in weight percentages based on total alloy weight, 3.4 to 4.4.

14. The titanium alloy of claim 6 , wherein a zirconium content in the alloy is, in weight percentages based on total alloy weight, 3.5 to 4.3.

15. The titanium alloy of claim 7 , wherein a silicon content in the alloy is, in weight percentages based on total alloy weight, 0.03 to 0.11.

16. The titanium alloy of claim 7 , wherein a silicon content in the alloy is, in weight percentages based on total alloy weight, 0.06 to 0.11.

17. The titanium alloy of claim 6 , wherein a germanium content in the alloy is, in weight percentages based on total alloy weight, 0.1 to 0.4.

18. A titanium alloy consisting essentially of, in weight percentages based on total alloy weight:

2 to 7 aluminum;

0 to 5 tin;

0 to 5 molybdenum;

0.1 to 10.0 zirconium;

0.01 to 0.30 silicon;

0.05 to 0.4 germanium;

0 to 0.30 oxygen;

0 to 0.30 iron;

0 to 0.05 nitrogen;

0 to 0.05 carbon;

0 to 0.015 hydrogen;

titanium; and

impurities.

19. A titanium alloy consisting essentially of, in weight percentages based on total alloy weight:

5.5 to 6.5 aluminum;

1.5 to 2.5 tin;

1.3 to 2.3 molybdenum;

0.1 to 10.0 zirconium;

0.01 to 0.30 silicon;

0.1 to 2.0 germanium;

0 to 0.30 oxygen;

0 to 0.30 iron;

0 to 0.05 nitrogen;

0 to 0.05 carbon;

0 to 0.015 hydrogen;

0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt, and copper;

titanium; and

impurities.

20. The titanium alloy of claim 19 , wherein an aluminum content in the alloy is, in weight percentages based on total alloy weight, 5.9 to 6.0.

21. The titanium alloy of claim 19 , wherein a tin content in the alloy is, in weight percentages based on total alloy weight, 1.7 to 2.1.

22. The titanium alloy of claim 19 , wherein a tin content in the alloy is, in weight percentages based on total alloy weight, 1.9 to 2.0.

23. The titanium alloy of claim 19 , wherein a molybdenum content in the alloy is, in weight percentages based on total alloy weight, 1.7 to 2.1.

24. The titanium alloy of claim 19 , wherein a molybdenum content in the alloy is, in weight percentages based on total alloy weight, 1.8 to 1.9.

25. The titanium alloy of claim 19 , wherein a zirconium content in the alloy is, in weight percentages based on total alloy weight, 3.4 to 4.4.

26. The titanium alloy of claim 19 , wherein a zirconium content in the alloy is, in weight percentages based on total alloy weight, 3.5 to 4.3.

27. The titanium alloy of claim 19 , wherein a silicon content in the alloy is, in weight percentages based on total alloy weight, 0.03 to 0.11.

28. The titanium alloy of claim 19 , wherein a silicon content in the alloy is, in weight percentages based on total alloy weight, 0.06 to 0.11.

29. The titanium alloy of claim 19 , wherein a germanium content in the alloy is, in weight percentages based on total alloy weight, 0.1 to 0.4.