单晶γ-TiAl中孔洞尺寸对裂纹扩展影响的分子动力学模拟

Effect of holes size on single crystal γ –TiAl alloy crackpropagation based on molecular dynamics simulation

摘要:

运用分子动力学方法研究单晶γ-TiAl合金的裂纹扩展行为，模拟时采用嵌入原子势方法，结合原子轨迹图、能量演化图以及应力-应变曲线，分析不同孔洞尺寸对裂纹扩展过程的影响。结果表明：随着孔洞半径增大，裂纹的启裂应力值减小；裂纹与孔洞结合后，R=1?时，孔洞变形后在孔洞边界的中心产生裂纹，沿[100]方向扩展至材料断裂，裂纹扩展中出现子母裂纹传播现象；R=2?时，孔洞变形后在一角处产生裂纹，沿[100]方向扩展至材料断裂；R=3?时，孔洞变形后在两个角处产生裂纹，沿[110]和 方向扩展，[110]方向裂纹扩展中出现子母裂纹传播现象，且边界产生子裂纹并与该方向裂纹汇合后扩展至材料断裂; 此外孔洞抑制裂纹扩展。

Abstract:

Molecular dynamics method has been applied to the research on the process of crack propagation of single crystal γ-TiAl. The atomic trajectory figure, energy evolution and the relationship between stress and strain were obtained after the holes size effect had been studied. The results indicate that the initiation stress decreased with holes size increased. After the crack combined with the hole: when R=1?, crack occurred at the center of holes boundary after holes deformation , and it propagated along the direction of [100] until material fracture, mother-child model was found; when R=2?, crack occurred at one corner after holes deformation, and it propagated along the direction of [100] until material fracture; when R=3?, crack occurred at two corners after holes deformation, and it propagated along the direction of [110]and , which mother-child model was found at the direction of [110], and child crack occurred at boundary which combined with crack in this direction and propagate until material fracture. In addition the crack propagate was inhibited by the hole.