Hot Deformation Behavior and Microstructure Evolution of a High Nb Containing PM TiAl Composite Reinforced with Ti2AlC Particles

Abstract The hot deformation behavior and microstructure evolution of a PM TiAl alloy with a nominal composition of Ti-45Al-10Nb (at%.) reinforced with Ti2AlC particles were investigated by isothermal compression tests at temperatures ranging from 950 °C to 1100 °C, and at strain rates from 0.1 s−1 to 0.001 s−1. The true stress-strain curves exhibited a typical single peak characteristic. A hyperbolic-sine-type Arrhenius equation can describe the dependence of the peak stress on the deformation temperature and strain rate well. The calculated values of apparent activation energy and stress exponent were 389±25 kJ/mol and 4.4, respectively. The Ti2AlC inclusions served as an effective obstacle leading to the dislocation pile-up, which strengthened the alloy and induced recrystallization nucleation. Moreover, the grain growth was significantly restricted due to an obstructive effect on grain boundary migration by Ti2AlC particles. Based on microstructure analysis, the softening mechanism was dominated by dynamic recrystallization (DRX) with the assistance of dynamic recovery (DRV).