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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。
The as-cast microstructure of Ti-Al-Nb-WB alloy was optimized by two treatments of heat treatment and clad-forging combined thermo-mechanical treatment. The microstructure evolution of β (B2) Ternary phase diagram of the alloy microstructure evolution and growth mechanism was studied to determine the room temperature TiAl-based alloy block β (B2) phase of the basic process. The experimental results show that: (1) The β (B2) phase in the as-cast Ti-Al-Nb-WB alloy can be effectively eliminated by the heat treatment process in α + γ two- , The β (B2) phase can be obviously reduced and basically eliminated, and the grain size grows slightly; increasing the temperature of the heat treatment up to 1260 ° C can greatly shorten the holding time and also eliminate the effect of β (B2) phase, At the same time can also avoid the growth of grain size. (2) The massive β (B2) phase at the as-cast microstructure of the as-cast microstructure is basically broken and eliminated by the wrapping-forging combined thermal mechanical treatment with the total deformation greater than 80%, while the original as-cast lamellar structure is also Obviously optimized for a homogeneous, two-state structure.