Dynamic recrystallization, phase transformation and deformation mechanisms of a novel Ti-43Al-6Nb-1Mo-1Cr alloy during the isothermal deformation

Phase transformation and dynamic recrystallization (DRX) mechanisms of Ti-43Al-6Nb-1Mo-1Cr (at.%) alloys during the isothermal compression were investigated in this study. The deformed microstructure showed that at 1200 °C/0.005 s⁻¹, the continuous dynamic recrystallization (CDRX), which was characterized by crystal orientation accumulation, appeared in α₂-Ti₃Al phase (D0₁₉). Meanwhile, β-Ti phase (A2) deformed to support deformation of present alloys before dynamic recrystallization. In addition, microstructure characterization confirmed the occurrence of stress-induced γ → α₂ phase transformation in present TiAl alloys, which was dominated by the slip of 1/6 〈11−2〉 {111} partial dislocations within γ-TiAl phase (L1₀) during the loading. At strain 60%, α₂/γ lamellae were replaced by recrystallized α₂ grains, due to the stress-induced γ → α₂ phase transformation and the nucleation of recrystallized α₂ grains. Finally, deformation mechanisms of α₂, γ and β phases in high Nb containing TiAl alloys were discussed.