Abstract This work presents atomic simulations of crack tip behavior in HCP titanium single crystal with center crack under mode I loading condition. The simulation results show that the crack tip plasticity in most of the studied crack orientations is attributed to the activation of basal or prismatic 〈 a 〉 slips, which is in accordance with the slip characteristics analysis. Comparing the increment of crack tip advance with the applied strain under different conditions, it is found that brittle mode has the highest crack propagation rate, following by twinning dominated crack tip behavior and the latter is dislocation slip dominated crack tip behavior. The above toughness difference is further explained from the perspective of the atomic stress distribution in front of the crack tip. Finally, the simulation results are compared with theoretical predictions based on the linear elastic fracture mechanics. Besides, the observed crack kinking phenomenon is attributed to the preference of cleavage along the plane with lower critical stress intensity factor. In general, the simulation results indicate that titanium is an intrinsically ductile metal as plastic deformation can be observed in the vicinity of the crack tip for most of the studied crack orientations, though some slip modes that have relatively Schmid factors are suppressed by the applied boundary condition.

中文翻译：

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钛单晶中裂纹尖端行为的取向效应的原子模拟

摘要 这项工作提出了在模式 I 加载条件下具有中心裂纹的 HCP 钛单晶裂纹尖端行为的原子模拟。模拟结果表明，大多数研究裂纹方向的裂纹尖端塑性归因于基底或棱柱形<a>滑移的激活，这与滑移特性分析一致。比较不同条件下裂纹尖端推进的增量与外加应变，发现脆性模式裂纹扩展速率最高，其次是孪晶主导的裂纹尖端行为，后者是位错滑移主导的裂纹尖端行为。上述韧性差异从裂纹尖端前的原子应力分布角度进一步解释。最后，将模拟结果与基于线弹性断裂力学的理论预测进行比较。此外，观察到的裂纹扭结现象归因于具有较低临界应力强度因子的平面的解理偏好。一般来说，模拟结果表明钛是一种固有的延展性金属，因为对于大多数研究的裂纹方向，在裂纹尖端附近可以观察到塑性变形，尽管一些具有相对施密特因子的滑移模式被应用边界抑制状况。