Effects of Heat Treatment on Microstructure and Tensile Properties at High Temperature of Powder Metallurgy Ti-45Al-7Nb-0.3W-0.1B Alloy

The effect of heat treatment processes on the microstructure of Ti-45Al-7Nb-0.3W-01B（at%） alloy prepared by powder metallurgy method was studied by OM and TEM. The tensile properties of Ti-45Al-7Nb-0.3W-01B（at%） alloy were tested at 750 ℃ and 800 ℃. The results show that the tensile properties of the alloy after heat treatment are related to the size of lamellar grains, the content of residual γ grains and the lamellar spacing. The higher the content of residual γ grains, the more likely the alloy is to fracture. The tensile strength of the alloy is lower when the lamellar size and spacing are too large.After heat treatment at 1380 ℃/30 min, the alloy has excellent comprehensive mechanical properties. Its tensile strength at750 ℃ and 800 ℃ is 450 MPa and 435 MPa, the yield strength is 315 MPa and 300 MPa, and the elongation is 1.5% and 6.1%, respectively.