Effect of Al content on the hot deformation behavior and microstructure evolution of TiAl-6(Cr, Nb, Ta) alloy

The effect of Al content on the hot deformation behavior and microstructure evolution of TiAl-6 (Cr, Nb, Ta) alloy was studied by hot compression tests. The results show that when the alloy presented a low Al content, it contained a greater percentage of beta + gamma mixed structure at the grain boundary, and a finer lamellar colony size. Under the same deformation conditions, a reduction in Al content lead to a reduction in flow stress, but the hot deformation activation energy Q increased from 540 kJ mol(-1)to 617 kJ mol(-1). The increase of the beta + gamma mixed structure at the grain boundary promoted the rotation of the lamellar colony, thereby inhibiting the lamellar twisting process, and also reducing the dynamic recrystallization volume fraction. Reducing the strain rate and increasing the amount of strain can increase the dynamic recrystallization volume fraction of the alloys. When extruded at 1150 degrees C with an extrusion ratio of 10:1, both alloys containing Al presented a completely recrystallized structure.