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采用预合金粉末热等静压工艺制备了Ti-22Al-24Nb-0.5Mo(原子分数,%)粉末合金,对Ti-22Al-24Nb-0.5Mo粉末合金环坯和板坯进行电子束焊接.采用OM,SEM,EPMA和X射线三维成像技术对焊接接头的微观组织进行表征,研究了焊后热处理对焊接接头显微硬度、拉伸性能和持久性能的影响.结果表明,热等静压温度显著影响Ti-22Al-24Nb-0.5Mo粉末合金的孔隙分布.在1030oC热等静压成型的粉末环坯经980oC,2 h,真空炉冷热处理后表现出较好的可焊性.焊接接头熔合区、热影响区和母材的化学成分均匀,虽然显微组织差异明显,但是显微硬度无明显区别.拉伸及持久性能测试试样皆断裂于熔合区.焊接接头熔合区存在大量的显微孔隙是焊接接头发生断裂的失效机制.焊后热处理可以减少焊缝处的显微孔隙数量,从而提高焊接接头塑性及高温持久寿命.
The Ti-22Al-24Nb-0.5Mo (atomic fraction,%) powder alloy was prepared by pre-alloyed powder hot isostatic pressing, and the electron beam welding of Ti-22Al-24Nb-0.5Mo alloy powder ring and slab was carried out. The microstructure of the welded joint was characterized by OM, SEM, EPMA and X-ray imaging. The effect of post-weld heat treatment on the microhardness, tensile property and permanent property of the welded joint was studied. The results showed that the hot isostatic pressing temperature was significant Which affected the pore distribution of Ti-22Al-24Nb-0.5Mo powder alloy.It showed better solderability after hot isostatic pressing at 1030oC for 2h at 980oC, 2h, The chemical composition of the HAZ and the base metal are uniform. Although the differences of the microstructure are obvious, there is no obvious difference in the microhardness. The tensile and ductility test specimens are all broken in the fusion zone. Microporosity is the failure mechanism of the fracture of the welded joint.The post-weld heat treatment can reduce the number of micro-pores at the weld, thus improving the plasticity of the welded joint and the long-life at high temperature.