Microstructure evolution of the Ti-45Al-8.5Nb-W-Mo-Y alloy

The phase constitution of Ti-45Al-8.5Nb-W-Mo-Y alloy was studied. The results show that the microstructure of the as-cast alloy exhibits α₂+γ lamellae with a few B₂+ω phases. After 1200°C, 2 h annealing, the high temperature phases are transformed into the ω phase. After 70%-80% hot deformation, the microstructure of the alloy consists of bent lamellae, resident high temperature phases and equiaxed γ grains. The amount of resident high temperature phases can be decreased after 1280°C, 2 h treatment, and the amount of α₂ laths increases. Bent lamellae and equiaxed γ grains construct the as-extruded microstructure. The cyclic heat treatment can also be used to refine the grains.