1. Xi‘an Sailong AM Technologies Co. , Ltd. , Xi‘an 710018, China
2. State Key Laboratory of Porous Metals Materials, Northwest Institute for Nonferrous Metal Research,Xi’an 710016, China
In this paper, Ti2AlNb alloy samples fabricated by selective electron beam melting (SEBM) technology were treated with different heat treatment systems. The microstructure and phase composition of heat-treated samples were analyzed,the microhardness, tensile properties at room temperature and 650℃ and fracture morphology of the samples were evaluated.The results indicate that the microstructure of the heat-treated samples is mainly composed of B2 matrix phase,lath-like primary O/ α2 phase with large grain size and fine secondary needle O phase. Ti2AlNb alloy samples after 950 ℃ solution treatment and 700 ℃ aging treatment exhibit more needle-like O phase and α2 phase. The lath O/ α2 phase of samples after 800 ℃ aging treatment is coarsened to some extent. The heat-treated samples exhibit a microhardness
of 3190 ~ 3210 MPa. After aging treatment at 700 ℃, the samples show a higher ultimate tensile strength of (1068±12. 22) MPa and (843±39. 72) MPa at room temperature and 650 ℃ respectively. After aging treatment at 800 ℃, the samples show better tensile elongation of (7. 30±0. 58)% and (8. 50±0.50)% at room temperature and 650 ℃ respectively. After aging treatment at 700 ℃, the tensile fracture of the samples at room temperature exists cracks with large size. From the tensile fracture of samples after aging treatment at 800 ℃, no crack is found. Tensile fracture at high temperature shows a large number of dimples, exhibiting ductile fracture characteristics.