Dynamic recrystallization behavior of the Ti–48Al–2Cr–2Nb alloy during isothermal hot deformation

The hot deformation behavior of the as-cast Ti–48Al–2Cr–2Nb alloy was investigated by isothermal compression tests at deformation temperatures ranging from 1000 °C to 1200 °C, and strain rates from 0.001 s⁻¹ to 0.1 s⁻¹. The single peak stress features common to all flow curves indicate that DRX is the dominating softening mechanism. The calculated values of the hot deformation activation energy Q and stress index n are 296.5 kJ mol⁻¹ and 3.97, respectively. Based on this, the Arrhenius type constitutive equation was successfully established. The DRX critical condition model and relationship among DRX volume fractions, deformation temperatures and strain rates were obtained to optimize the process. Combined with microstructure analysis, it's concluded that 1200 °C/0.01s⁻¹ is the optimization parameter. Besides, both DDRX and CDRX were observed in the γ phase evolution. The deformation mechanism from the inter-grain dislocation motion to the grain boundary migration and grain rotation was discussed.