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本文采用ＴＥＭ原位拉伸技术研究了处于不同取向的全层状结构的Ｔｉ－４９％Ａｌ（原子分数）合金（ＰＳＴ晶体）的断裂机制．结果表明：ＰＳＴ晶体裂纹萌发及扩展机制强烈依赖于ＰＳＴ晶体的晶体学取向，裂纹尖端位错发射能力的不同和界面的约束是造成不同取向ＰＳＴ晶体具有不同断裂机制的根本原因．
In this paper, the fracture mechanism of Ti-49% Al (atomic fraction) alloy (PST crystal) with full orientation in different orientations was investigated by TEM in-situ tensile technique. The results show that the mechanism of crack initiation and propagation in PST crystal is strongly dependent on the crystallographic orientation of PST crystal. The different dislocation emissivity at crack tips and interface constraints are the fundamental reasons for the different fracture mechanisms of PST crystals with different orientations.