Deformation-induced α₂ → γ phase transformation in TiAl alloys

Deformation-induced α₂ → γ phase transformation in high Nb containing TiAl alloys was investigated using high-resolution transmission electron microscopy (HREM) and energy dispersive X-ray spectroscopy (EDS). The dislocations appearing at the tip of deformation-induced γ plate (DI-γ) and the stacking sequence change of the α₂ matrix were two key evidences for determining the occurrence of the deformation-induced α₂ → γ phase transformation. Compositional analysis revealed that the product phase of the room-temperature transformation was not standard γ phase; on the contrary, the product phase of the high-temperature transformation was standard γ phase.