Microstructural evolution, hot workability, and mechanical properties of Ti-43Al-2Cr-2Mn-0.2Y alloy

This study systematically investigated the microstructural evolution, hot workability, and mechanical properties of the β-γ TiAl alloy Ti-43Al-2Cr-2Mn-0.2Y. The as-cast alloy had a wide hot working window and excellent hot workability. A crack-free pancake was obtained through one-step canned forging with an initial deformation condition of 1200°C/0.1s^-1. The coarse lamellar microstructures of the as-cast alloy were broken down into fine γ grains after forging. Residual lamellae were hardly observed even near the edge of the pancake. Dynamic recrystallization of γ grains was the main softening mechanism during hot forging. Tensile tests showed that the as-forged alloy exhibited better room temperature tensile properties than the as-cast alloy because of microstructural refinement and homogenization. The ultimate tensile strength of the as-forged alloy at 700°C was maintained at 496 MPa, and elongation was 10%. The ductile-brittle transition temperature was between 700 and 750°C. In addition, the nano-hardness values of the β₀ and γ phases were 5.6 and 4.6 GPa, respectively. The hardness of the β₀ phase was lower than that of the β₀ phase in TNM alloys, indicating that the hardness of the β₀ phase highly depended on alloying elements.