热处理对激光增材制造Ti_2AlNb基合金组织及性能的影响

Effect of Heat Treatment on Microstructure and Properties of Laser Additive Manufactured Ti_2AlNb-Based Alloy

利用激光增材制造技术制备出Ti-22Al-25Nb合金薄壁试样,分析了沉积态和热处理态试样的宏观形貌、相组成和显微组织,以及不同制度热处理态试样的组织和室温拉伸性能。结果表明,沉积态试样相组成沿沉积高度方向呈现由B2+O+α_2→B2+O→B2的变化趋势;热处理态试样的微观组织和相组成均匀,由B2、O、α_2 3相组成;经930℃保温2h空冷的固溶处理和800℃保温24h空冷的时效处理后,合金室温拉伸性能好,抗拉强度为1017MPa,断后伸长率为6.0%。

Thin-wall samples of Ti-22Al-25 Nb alloy are prepared through the laser additive manufacturing process. The macro morphology, phase composition and microstructure for as-deposited and heat-treated samples are investigated. In addition, the microstructure and room tensile properties of Ti-22Al-25 Nb alloy are analyzed after a series of heat treatments. The results indicate that for the as-deposited sample, the phase transforms as B2＋O＋α_2→B2＋O→B2 along the build-up direction, while the phase composition and microstructure of heat-treated sample become homogeneous, which is composed of B2, O and α_2 phases. After solution treatment of 930 ℃ ×2h/air cooling followed by aging treatment of 800℃ × 24h/air cooling, the laser additive manufactured Ti_2AlNb alloy shows better tensile properties with ultimate tensile strength of 1017 MPa and elongation of 6.0%.