Effects of annealing on microstructure and mechanical properties of γ-TiAl alloy fabricated via laser melting deposition
(School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China)
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 γm (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