Abstract:The microstructure evolution and mechanical properties of the as-deposited γ-TiAl-based alloy specimen fabricated via laser melting deposition and as-annealed specimens at different temperatures were investigated. The results show that the microstructure of as-deposited specimen is composed of fine α₂(Ti₃Al)+γ lamellae. With the increase of annealing temperature, the bulk γ_m (TiAl) phase gradually changes from single γ phase to γ phase + acicular α₂ phase, finally small γ phase + lamellar α₂₊γ phase. Compared with the mechanical properties of as-deposited γ-TiAl alloy (tensile strength 469 MPa, elongation 1.1%), after annealing at 1260 °C for 30 min followed by furnace cooling (FC), the room-temperature tensile strength of the specimen is 543.4 MPa and the elongation is 3.7%, which are obviously improved.

Key words: laser melting deposition; annealing; TiAl alloy; microstructure evolution; mechanical properties