Although metallic glasses (MGs) exhibit exceptional mechanical properties, their practical applications are often hindered by operational conditions that induce cyclic stress and strain fluctuations, leading to sudden failure through rapid shear-banding. Combining experimental tests and molecular dynamic (MD) simulations, we find that although cyclic stress induces the accumulation of shear instability and promotes shear bands (SBs) growth, a unique ‘self-repair’ process occurs inside mature SBs evidenced by an obvious decrease in potential energy and increase in stabilized cluster connections. The unique self-repair behavior is elaborated by coupling the STZ-vortex model and medium-range order (MRO) clusters defined by the gradient atom stacking structure, which suggests that the rotation centers composed of rigid solid-like clusters activate the inelastic deformation within surrounding atoms. Such shear-banding dynamic reveals that the self-repair event is caused by the transition from liquid-like atoms to opposite solid-like counterparts, which correlates strongly with enhancing face-sharing connections of MRO. These findings advance our understanding of structural evolution and plastic events during cyclic deformation of MGs.

中文翻译：

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循环纳米压痕作用下 CuZr 金属玻璃的剪切带动力学及自修复机制：实验与分子动力学模拟


尽管金属玻璃 （MG） 表现出卓越的机械性能，但其实际应用经常受到引起循环应力和应变波动的操作条件的阻碍，从而导致快速剪切带突然失效。结合实验测试和分子动力学 （MD） 模拟，我们发现，尽管循环应力会诱导剪切不稳定性的积累并促进剪切带 （SBs） 的增长，但成熟的 SBs 内部会发生独特的“自我修复”过程，其表现为势能的明显降低和稳定的簇连接增加。通过将 STZ 涡旋模型与梯度原子堆叠结构定义的中程有序 （MRO） 簇耦合来阐述独特的自修复行为，这表明由刚性固体状簇组成的旋转中心激活了周围原子内的非弹性变形。这种剪切带动力学表明，自修复事件是由从液体状原子到相反的固体状对应物的转变引起的，这与增强 MRO 的面共享连接密切相关。这些发现促进了我们对 MGs 循环变形过程中结构演变和塑性事件的理解。