晶体相场模拟揭示晶粒取向与裂纹扩展关系

Relationship Between Grain Orientation and Crack Propagation Revealed by Phase-Field Crystal Simulation

摘要:

采用晶体相场法，研究了双晶系统在动态拉伸条件下，不同取向角度对纳米双晶体系中微裂纹扩展机制的影响。结果表明，相同拉伸条件下，裂纹扩展方式、裂纹体积分数、裂纹扩展速率与晶粒取向相关。同取向差裂纹扩展机制差异取决于裂纹尖端附近的位错活动，位于裂纹尖端的单个位错，易会导致裂纹发生脆性扩展，加快裂纹扩展速率；裂纹尖端多个方向不同的位错可能会发生位错缠结，进而阻碍裂纹扩展。

Abstract:

The influence of different orientation angles on the microcrack propagation mechanism in nano twin crystal system under dynamic tensile conditions was investigated using the phase-field crystal method. The results show that under the same tensile conditions, the crack propagation mode, crack volume fraction, and crack propagation rate are related to the grain orientation. The difference in the crack propagation mechanism of the same orientation depends on the dislocation activity near the crack tip. A single dislocation located at the crack tip can easily lead to brittle expansion of the crack and accelerate the crack propagation rate. Dislocations in different directions at the crack tip may tangle together, which in turn hinders the crack propagation.