Microstructural characteristics and dynamic recrystallization behavior of β-γ TiAl based alloy during high temperature deformation

Microstructural characteristics and dynamic recrystallization behavior of the alloy with an actual composition of Ti-42.89Al-4.01Nb-0.99Mo-0.19B are studied through hot uniaxial compression tests under different deformation conditions. Results show that there exists a critical deformation temperature, when deformation temperature is lower than it, the extent of DRX increases with the increasing temperature. On the contrary, the extent of DRX does not increase any more with the increasing temperature. Completely dynamic recrystallization appears in β phase when deformation temperature exceeds 1100 °C and strain rate is below 0.01 s⁻¹, resulting in the occurrence of equiaxed β phases. Moreover, DRX behavior is discussed, and the twin-related nucleation mechanism is detected in this study. In addition, the perfect Burgers orientation relationship is identified between the previous α₂ lath and newborn β phase in remnant lamellar colony, resulting from α₂ → β phase transformation during hot deformation which delays the decomposition of remnant lamellar structure.