Effects of Sintering Temperature on Microstructure Evolution and Hot Deformation Behavior of TiAl-Based Alloys Prepared by Spark Plasma Sintering

TiAl-based alloys have been regarded as potential substitute materials for heavy Ni super-alloys. To understand the relationship of the processing-microstructure-hot deformation behavior of TiAl-based alloys fabricated via the spark plasma sintering technique, alloys were sintered at a temperature range of 1150–1350°C. Subsequently, isothermal compression tests were carried out at 1125°C with a strain rate of 0.1 s⁻¹. The pre-alloyed powders, which showed dendritic structures, were mainly composed of α₂ phase and a few of γ phase. Alloys composed of near gamma, duplex, and fully lamellar microstructures were obtained after sintering at 1150–1250°C, 1300°C, and 1350°C, respectively. The compressive peak stress increased with increasing sintering temperature, and the alloy sintered at 1250°C exhibited a better hot deformability. Moreover, dynamic recrystallization and phase transformation of α₂ → γ occurred during isothermal compression.