The as cast microstructure of high-Nb contained TiAl-based alloys exhibits coarse and inhomogeneous

and there exists a little of B

2

phase and long strip silicide and boride precipitated along the grain boundaries

resulting in the degradation of alloy plasticity

strength and fracture toughness at room temperature.The influences of different heat treatments on the structure of Ti-45Al-8Nb-0.5W-0.8B-0.2Si alloy were investigated

and homogenization heat treatment and cycle heat treatment were adopted to eliminate segregation

improve phase composition and refine layer microstructure.The results show that desirable microstructure can be observed in the alloy by the homogenization process along with the furnace heated to 1 200℃for 24 h

and then air cooling and then recycle heat treatment with rapidly heated to 1 150 ℃for 4h

air cooling

repeating the process three times.