运用分子动力学方法对单晶γ-TiAl 合金的裂纹扩展过程进行了研究，分析了不同孔洞位置对裂纹扩展的影响，得到相应的原子轨迹、能量演化以及应力-应变关系.结果表明无孔洞时，裂纹以脆性解理方式快速扩展至材料断裂，能量曲线只有一个波峰；L＝1．6 nm时裂纹先以脆性解理的方式扩展，孔洞抑制裂纹扩展，孔洞周围发射位错，裂纹以尖端空洞形核、长大成微裂纹，最终微裂纹与主裂纹连接的方式扩展，能量曲线有多个峰值；L＝4．8 nm时，裂纹初始扩展过程与L＝1．6 nm时相似，后期未出现空洞形核、长大成微裂纹并与主裂纹结合的现象；另外孔洞距裂尖距离不同，发射第一个位错的方向不同.
Molecular dynamics method has been applied to the research on the process of crack propagation of sin-gle crystalγ-TiAl,the atomic traj ectory figure,energy evolution and the relationship between stress and strain were obtained after the holes position effect had been studied.The results indicate that the crack propagates quickly in the form of brittle cleavage until the material fractures when there is no hole model in the material and only one wave crest could be discovered in the energy curve;In the case of L=1 .6 nm,the crack propagates in the form of brittle cleavage at first.Then,the propagation was inhibited by the hole,and dislocations emit a-round the hole.Next,micro cracks grow up by void nucleation.Finally,the coalescence and link-up between micro cracks and the main crack would turn into the main form of cracks propagation,and more wave crests could be discovered in energy curve;As for L=4.8 nm,the initial process of cracks propagations similar to the L=1 .6 nm,but void nucleation,growth,coalescence and link-up with the main crack could not appear at the later stage;also,the emission direction of the first dislocation is different when crack tips have a different dis-tance from holes.
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