Dynamic recrystallization and phase transformation behavior of a wrought β-γ TiAl alloy during hot compression

The dynamic recrystallization (DRX) and phase transformation (PT) behavior of a wrought beta-gamma TiAl alloy during hot compression under various deformation temperatures were investigated. The typical work hardening and flow softening features indicated that DRX was the dominating softening mechanism. Both gamma-DRX and beta-DRX took place during the hot compression. gamma-DRX was triggered at all compression temperatures, while the beta-DRX was induced when the compression temperature was above 1000 degrees C. The hot deformation kinetics was calculated, which showed that DRX behavior existed in the whole hot compression process, and the DRX volume fraction increased with the increase of the compression temperature. Combined with the microstructure observation, it concluded that the beta/B2+ alpha(2 ->gamma) PT occurred at 850 degrees C and 1000 degrees C, while the gamma ->beta/B2 PT happened at 1050 degrees C during hot compression, which is important to optimize microstructure. Moreover, the hot compression mechanism changed from dislocation gliding to grain-boundary sliding was discussed.