通过 SEM原位拉伸技术和双晶体压缩实验研究了全片层 Ti Al基合金晶界断裂行为。研究表明 ,在全层状组织的断裂行为中 ,晶界具有双重作用。一方面 ,微裂纹首先萌发于晶界区 ,其扩展方式取决于晶界两侧片层的取向。另一方面 ,不同类型的晶界对裂纹扩展的阻力不同 ,因而对全层状 Ti Al基合金韧性的作用不同 ,纵向晶界有助于断裂韧性的提高 ,而横向晶界对合金韧性不利 The fracture behavior of the whole lamellar TiAl-based alloy was investigated by SEM in situ tensile test and twin crystal compression experiment. It has been shown that grain boundaries have a dual role in the fracture behavior of full-thickness structures. On the one hand, micro-cracks first germinate in the grain boundary region, and its expansion depends on the orientation of the sheets on both sides of the grain boundary. On the other hand, the resistance of different types of grain boundaries to crack propagation is different, and thus the effect on the toughness of full-layered TiAl-based alloys is different. The longitudinal grain boundaries contribute to the improvement of fracture toughness, whereas the transverse grain boundaries are detrimental to the toughness of the alloy