【摘要】 采用热处理和包套锻复合热机械处理两种路线对Ti-Al-Nb-W-B合金铸态组织进行了优化,观察在各种制度下β(B2)相的组织演变,对照Ti-Al-Nb三元相图对合金组织形貌演变及生长机理进行了研究,确定了消除室温TiAl基合金中晶界块状β(B2)相的基本工艺。实验结果表明:(1)采用在α+γ两相区的热处理工艺可以有效地消除Ti-Al-Nb-W-B合金铸态组织中的β(B2)相:在1220°C保温36h随炉冷却,可以明显地减少并基本消除β(B2)相,晶粒尺寸略微长大;提高热处理的温度至1260°C,可以极大的缩短保温时间,也能达到消除β(B2)相的效果,同时还能避免晶粒尺寸的长大。(2)通过总变形量大于80%的包套锻复合热机械处理,铸态组织晶界处的块状β(B2)相基本被破碎和消除,同时原始铸态的层片状组织也被明显优化为均匀的双态组织。更多还原

【Abstract】 The microstructures of as-cast Ti-Al-Nb-W-B alloy were investigated to assess the possibility of eliminating the triaxial β(B2) phase on the crystal boundary through heat treatment and multi-step forging thermal mechanical treatment.The microstructure evolution and growth mechanism were studied according to Ti-Al-Nb ternary phase diagram,and then the process of eliminating of the triaxial β(B2) phase on the crystal boundary was assessed.The results of the experiments indicate that the best way to eliminate β(B2) phase is holding at the 1260 °C for 8 h or 1220 °C for 36 h followed by furnace cooling,but the grains grow appreciably.On the other hand,after multi-step forging with a total deformation of more than 80%,the as-cast nearly lamellar structure can be refined obviously to the duplex microstructure,and the β(B2) phase is basically eliminated.更多还原