Study on microstructure evolution and deformation softening mechanism of a Ti–47.5Al–2.5V–1.0Cr–0.2Zr alloy

The hot compression tests of Ti–47.5Al–2.5V–1.0Cr–0.2Zr alloy were achieved by a Gleeble thermal simulator. The results show that the residual lamellar microstructure has sufficient energy and sufficient time to decompose, which is conducive to the evolution of the dynamic recrystallisation (DRX) microstructure. The dislocation density decreases significantly owing to the generation of a DRX. The deformation mechanism during hot deformation is dominated by the DRX of the γ-phase. Meantime, the increment of dislocations will induce to the generation of sub-grain boundaries. In addition to the mechanism of dislocation-induced recrystallised grain formation, twinning deformation is also a typical deformation mechanism in TiAl alloy. The transformation of lamellar microstructure into uniform and fine DRX microstructure can improve the microstructural uniformity of the alloy.