Packed forging and microstructure optimization of β-solidified TiAl alloy

The displacement-load curves of Ti-43Al-5(Nb, Mo, B) alloy isothermally compressed at different strain rates and temperatures on Gleeble-1500D thermal-simulation machine were investigated. The results indicated that the load increased sharply first, and then kept constant, and finally increased again as the displacement increased continuously. A crack-free pancake was obtained when the ingot was packing forged at 1150°C and with strain rate of 0.1/s. The microstructure of the pancake consisted of major kinked/broken lamellae and dynamic recrystallization grains, minor residual β phase and remnant lamellae. After annealed at 1180°C for 5 hours, a homogeneous microstructure with fine and equiaxed grains was obtained. With elimination of the residual β phase, the uniformity of the microstructure was greatly improved as well.