为细化铸造TiAl基合金的显微组织,将成分为Ti-44.9Al、Ti-48Al以及Ti-44.3Al-3.0Cr(at%)的三种合金在略高于Ti-Al共析温度的1150℃进行长时保温处理。结果表明,保温一定时间后,合金中的Ti3Al+TiAl片层组织会发生三种类型的不连续粗化转变,转变结果均能在一定程度上细化合金的铸态晶粒尺寸,其中Ti-44.3Al-3.0Cr合金的晶粒细化效果最佳。此外,Al含量的增加,合金元素Cr的加入等都会大大促进合金的不连续粗化转变过程。

In order to obtain fine grain microstructure in as-cast TiAl based alloys, three alloys of Ti-44.9Al, Ti-48Al and Ti-44.3Al-3.0Cr(at%) were heat treated at 1150℃(just slightly above the TiAl eutectoid temperature). The results show that there are three typical types of discontinuous coarsening transformations of the Ti₃Al+TiAl lamellae in these Ti-Al based alloys and the ascast grain sizes of these TiAl alloys can be refined significantly by the discontinuous coarsening transformations. The best result of refining grains is achieved in Ti-44.3Al-3Cr alloy Moreover, the increase of aluminum content,addition of alloying element Cr can speed up the process of discontinuous coarsening greatly.