The influence of the dynamic softening mechanism of α phase and γ phase on remnant lamellae during hot deformation

Highlights: • The remnant lamellae in deformed microstructure of TiAl alloy are related to the phase fraction (α and γ phases). • The deformation softening mechanism of α phase is mainly dynamic recovery and continuous dynamic recrystallization. • The deformation softening mechanism of γ phase is mainly discontinuous dynamic recrystallization. • The formation process of remnant lamellae during hot deformation is determined. -- Abstract: In this paper, the remnant lamellae of Ti-45Al and Ti-48Al alloys were studied firstly. And then the dynamic softening mechanisms of α and γ phases during compression deformation were systematically investigated to understand the remnant lamellae formation. The results exhibit that the remnant lamellae in the deformed microstructure of TiAl alloy are related to content of α and γ phases. The main deformation softening mechanism of α phase is dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX), which reveals that a larger strain is needed for DRX of α phase. And the main deformation softening mechanism of γ phase is the discontinuous dynamic recrystallization (DDRX), illustrating that it is easier for γ phase to be fine grains. Comparing with α phase, the degree of DRX in γ phase is higher under the same compression conditions, and the average grain size of dynamic recrystallized γ grain is smaller than the dynamic recrystallized α grain. So, the remnant lamellae in the deformed microstructure of Ti-45Al alloy with high content of α phase are more than those of Ti-48Al alloy. Ultimately, the effect of the dynamic softening mechanism of α and γ phases on the formation of remnant lamellae during hot deformation is determined.