Self lubricating titanium aluminide composite material
A composite material having an alloy matrix including titanium, aluminum, niobium, manganese, boron, and carbon is disclosed. The composite material includes, by atomic percentage, 40.0% to 50.0% Al, 1.0% to 8.0% Nb, 0.5% to 2.0% Mn, 0.1% to 2.0% B, and 0.01% to 0.2% C. The composite material is doped with a solid lubricant such as MoS 2 , ZnO, CuO, hexagonal boron nitride (hBN), WS 2 , AgTaO 3 , CuTaO 3 , CuTa 2 O 6 , or combinations thereof. Components composed of the composite material exhibit increased ductility at room temperature and reduced fracture tendency, resulting in improved durability.
1. A composite material comprising:
a titanium aluminide alloy matrix including titanium, aluminum, niobium, manganese, boron, and carbon; and
a solid lubricant,
wherein the alloy matrix has a two-phase, fully lamellar microstructure, with the solid lubricant being dispersed therein;
wherein the composite material comprises, by atomic percentage, 40.0% to 50.0% Al, 1.0% to 8.0% Nb, 0.5% to 2.0% Mn, 0.1% to 2.0% B, and 0.01% to 0.2% C;
wherein the solid lubricant is present in the alloy matrix at an atomic percentage of 1% to 30% of the composite material.
2. The composite material according to claim 1 , wherein the solid lubricant consists of hexagonal boron nitride (hBN).
3. The composite material according to claim 1 , wherein the solid lubricant is substantially homogenously distributed as discrete, inert particles.
4. The composite material according to claim 1 , wherein the lamella have a maximum thickness of 1 μm.
5. The composite material according to claim 1 , wherein the titanium, aluminum, niobium, manganese, boron, and carbon are uniformly distributed throughout the alloy matrix.
6. The composite material according to claim 1 , wherein the composite material has a room temperature percent elongation of a minimum of 0.5%.
7. The composite material according to claim 1 , wherein the composite material has a coefficient of friction less than 0.065 from room temperature up to 800° C.
8. The composite material according to claim 1 , wherein the composite material has a wear rate less than 4.5×10 −4 mm 3 ·N −1 ·m −1 , from room temperature up to 800° C.
9. A bearing comprising:
an outer member; and
an inner member in sliding engagement with the outer member;
wherein at least one of the inner member and the outer member consists of the fully lamellar composite material according to claim 1 .
10. The composite material of claim 1 , wherein the solid lubricant consists of MoS 2 .
11. The composite material of claim 1 , wherein the solid lubricant consists of ZnO.
12. The composite material of claim 1 , wherein the solid lubricant consists of CuO.
13. The composite material of claim 1 , wherein the solid lubricant consists of WS 2 .
14. The composite material of claim 1 , wherein the solid lubricant consists of AgTaO 3 .
15. The composite material of claim 1 , wherein the solid lubricant consists of CuTaO 3 .
16. The composite material of claim 1 , wherein the solid lubricant consists of CuTa 2 O 6 .
17. A composite material comprising:
a titanium aluminide alloy matrix including titanium, aluminum, niobium, manganese, boron, and carbon; and
a solid lubricant,
wherein the alloy matrix has a two-phase, near-fully lamellar microstructure, with the solid lubricant being dispersed therein;
wherein the composite material comprises, by atomic percentage, 40.0% to 50.0% Al, 1.0% to 8.0% Nb, 0.5% to 2.0% Mn, 0.1% to 2.0% B, and 0.01% to 0.2% C;
wherein the solid lubricant is present in the alloy matrix at an atomic percent of 1% to 30% of the composite material.
18. The composite material according to claim 17 , wherein the solid lubricant consists of hexagonal boron nitride (hBN).
19. The composite material according to claim 17 , wherein the solid lubricant is substantially homogenously distributed as discrete, inert particles.
20. The composite material according to claim 17 , wherein the lamella have a maximum thickness of 1 μm.
21. The composite material according to claim 17 , wherein the titanium, aluminum, niobium, manganese, boron, and carbon are uniformly distributed throughout the alloy matrix.
22. The composite material according to claim 17 , wherein the composite material has a room temperature percent elongation of a minimum of 0.5%.
23. The composite material according to claim 17 , wherein the composite material has a coefficient of friction less than 0.065 from room temperature up to 800° C.
24. The composite material according to claim 17 , wherein the composite material has a wear rate less than 4.5×10 −4 mm 3 ·N −1 ·m −1 , from room temperature up to 800° C.
25. The composite material of claim 17 , wherein the solid lubricant consists of MoS 2 .
26. The composite material of claim 17 , wherein the solid lubricant consists of ZnO.
27. The composite material of claim 17 , wherein the solid lubricant consists of CuO.
28. The composite material of claim 17 , wherein the solid lubricant consists of WS 2 .
29. The composite material of claim 17 , wherein the solid lubricant consists of AgTaO 3 .
30. The composite material of claim 17 , wherein the solid lubricant consists of CuTaO 3 .
31. The composite material of claim 17 , wherein the solid lubricant consists of CuTa 2 O 6 .
32. A bearing comprising:
an outer member; and
an inner member in sliding engagement with the outer member;
wherein at least one of the inner member and the outer member consists of the near-fully lamellar composite material according to claim 17 .
33. The composite material of claim 1 , wherein impurities are trapped within α 2 layers of the microstructure.
34. The composite material of claim 33 , wherein the impurities are associated with a powder metallurgical process used to make the composite material.
35. The composite material of claim 33 , wherein the impurities comprise either one or both of carbon and oxygen.
36. The composite material of claim 1 , wherein grain boundaries of the composite material are refined by precipitation of TiB 2 at the grain boundaries.
37. The composite material of claim 1 , wherein
the alloy matrix is composed of α 2 layers and γ layers,
the α 2 layers are composed substantially of Ti 3 Al,
the γ layers are composed substantially of TiAl, and
the α 2 layers and the γ layers have a maximum thickness of 0.1 μm to 1 μm.