1 Xi'an Sailong Metal Materials Co., Ltd., Xi'an 710018, China 2 State Key Laboratory for Porous Metals Materials, Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China
Ti2AlNb based alloys is considered to be the most potential material material to replace the traditional Ni-based superalloys, because of its excellent high-temperature specific strength, creep resistance and high fracture toughness. Ti-22Al-25Nb alloy was fabricated by selective electron beam melting(SEBM), and the density of as-built samples reached 5.42-5.43 g/cm3through process optimization. The microstructure, phase evolution and mechanical property of the as-built and HIPed Ti2AlNb alloy samples were investigated. The results show that the microstructure of the as-built and HIPed samples both show the columnar crystalline structures along the deposition direction, which are all composed of B2, O and α2 phases, and the amount of O/α2 phase gradually increases from top to bottom. After HIP, the width and amount of the O/α2 phase are reduced and relatively uniform when compared with that of the as-built samples. In the bottom area, the microhardness of the as-built sample exhibits higher value of about (345.87±5.09)HV, while the hardness increases to 388.91-390.48HV after HIP. The ultimate tensile strength and elongation of the as-built sample at room temperature are (1061±23.71) MPa and (3.67±1.15)% respectively, and the ultimate tensile strength increases to (1101±23.07) MPa and the elongation reduces to 3.5% after HIP.
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