中文摘要：

针对冷坩埚定向凝固条件下获得的大尺寸TiAl基合金坯锭试样,采用不同热处理工艺参数,包括普通退火处理,温度循环热处理和快速加热循环热处理,并对坯锭热处理前后的组织和力学性能进行了比较。结果表明,合适的热处理工艺在不改变原始定向凝固钛铝基合金的晶粒状态的同时,可以使柱状晶内片层组织变得均匀和细小致密,并提高了其力学性能。定向凝固试样在1360℃温度以上出现再结晶和晶粒长大现象,而温度低于1150℃时则不然。温度循环热处理和快速加热循环热处理对细化定向凝固组织TiAl基合金的全片层组织都起到很好的促进作用。

英文摘要：

Large size Ti-46Al-0.5Si-0.5W slabs solidified directionally with a cold crucible continuous melting method were heat-treated in different processes,including conventional solid solution treatment,cyclic heat treatment and rapid heating cyclic heat treatment.Microstructure and mechanical properties of the slabs with and without heat-treatment were investigated.Results show that appropriate heat treatment is able to refine the lamellar structure of TiAl-based alloy.Also it can homogenize structure and improve mechanical properties of the alloy,while keeping the column grains in original state.Recrystallization occurs and the grains grow larger when the as-DS slabs are heated above 1360 ℃,but they do not change in size below 1150 ℃.Cyclic heat treatment and rapid heating cyclic heat treatment are more effective on refining lamellae and improving mechanical properties than the conventional solid solution treatment.