CuZr金属玻璃中应力过冲和锯齿的原子起源
Atomistic origin of stress overshoots and serrations in a CuZr metallic glass
摘要：
在这项工作中，我们使用分子动力学模拟研究的应力过冲的金属玻璃Cu $_{50}$ Zr $_{50}$在三种情况下（卸载-重新加载，滑动-停止-滑动，和应力锯齿）与剪切带松弛。我们发现，弹性恢复效应后，剪切带中的原子体积在压缩松弛过程中几乎没有变化，但在拉伸松弛过程中减少，而本地五重对称性增加一致的情况下。我们建议，原子机制相关的应力过冲是由于结构对称性的松弛，而不是自由体积，在剪切带。卸载时，传播的剪切带在停止之前持续一段时间，这导致应力下冲，并可能导致材料在循环弹性载荷下的疲劳。由于模拟的应变率非常高，我们没有通过分子动力学模拟直接观察到应力锯齿。虽然非热准静态模拟产生锯齿状的流动应力，我们注意到，这种锯齿状的结果从全球雪崩的剪切事件，而不是松弛的剪切带。
英文摘要：
In this work we use molecular dynamics simulations to study the stress overshoots of metallic glass Cu$_{50}$Zr$_{50}$ in three scenarios (unloading-reloading, slide-stop-slide, and stress serrations) that are associated with shear band relaxation. We found that, after the elastic recovery effect is factored out, atomic volume in the shear band barely changes during compressive relaxation but decreases during tensile relaxation, while local fivefold symmetry increases consistently for both cases. We propose that the atomistic mechanism for the related stress overshoots is due to the relaxation of structural symmetry, instead of free volume, in the shear band. Upon unloading, a propagating shear band continues for some time before arrested, which results in a stress undershoot and could contribute to material fatigue under cyclic elastic loads. We did not directly observe stress serrations via molecular dynamics simulations due to the very high simulated strain rates. While athermal quasistatic simulations produce serrated flow stress, we note that such serrations result from global avalanches of shear events rather than the relaxation of the shear band.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
