Design of low-cost titanium aluminide intermetallics

For titanium aluminide (TiAl) alloys, the high cost mainly comes from the forming process since the workability of TiAl alloys is quite low. To optimize the workability, introduction of β phase is an effective way. In the present study, a novel TiAl material alloyed with cheap β-stabilizing elements, Mo and Fe, was developed. The deformation behavior of the new alloy was characterized, and further alloying with interstitial elements to improve the high temperature properties was explored. Results show that the designed Ti-45Al-3Fe-2Mo at.% alloy has a fine grain β-stabilized microstructure. It shows a wide forging window, providing the foundation for an industrial forging process. The good deformability is derived from dynamic recrystallization of β phase and deformation-induced β → α2 + γ transformation. With the addition of 0.5% C, the creep properties can be significantly improved, which is mainly caused by the decrease in the amount of β phase and the precipitation of P-type carbides.