As a novel and highly promising metal in the future application of weapons equipment and aerospace fields, metallic glasses (MGs) demonstrate intricate failure modes that encompass both the brittle and plastic characteristics when subjected to varying loading conditions. In this work, a set of Cu50Zr50 models subjected to a combined pure shear and equi-triaxial tension loading are simulated via molecular dynamics to investigate the impact of the stress state on the complex failure modes of MGs. The characteristic and critical moments when failure occurs are established under both the shear-band-induced shear failure and the micro-void-induced tensile fracture. The stress triaxiality is applied as a pivotal stress parameter that governs the transition from the shear failure mode to the tensile failure mode. The critical stress triaxiality of Cu50Zr50 MG is approximately in the range of (2.0, 3.0) when both the shear and tension failures simultaneously occur, resulting in the largest failure strain at various stress states. We subsequently obtain a nearly elliptical yield surface of the Cu50Zr50 MGs, in which the shear failure zone, tensile failure zone, and transition zone are clearly distinguished. The microstructural evolution of MGs during the failure transition is analyzed from the perspective of the specific short-range order. In contrast to the tensile deformation, icosahedral (quasi-icosahedral) clusters demonstrate a high level of shear resistance and remain stable in the shear-dominant deformations, which is confirmed as the structural origin of the stress state impacting the failure transition.

中文翻译：

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金属玻璃中的应力诱导失效转变


金属玻璃 （MG） 作为未来武器装备和航空航天领域应用中一种极具前景的新型金属，在不同的载荷条件下表现出复杂的失效模式，包括脆性和塑性特性。在这项工作中，通过分子动力学模拟了一组承受纯剪切和等三轴拉伸载荷组合的 Cu50Zr50 模型，以研究应力状态对 MGs 复杂失效模式的影响。在剪切带诱发的剪切破坏和微空隙诱发的拉伸断裂下，都建立了失效发生的特征和临界矩。应力三轴性作为关键应力参数应用，控制从剪切破坏模式到拉伸破坏模式的过渡。当剪切和拉伸破坏同时发生时，Cu50Zr50 MG 的临界应力三轴性大约在 （2.0， 3.0） 范围内，导致在各种应力状态下失效应变最大。随后，我们获得了 Cu50Zr50 MGs 的近椭圆形屈服面，其中剪切破坏区、拉伸破坏区和过渡区被清晰区分。从特定的短程顺序的角度分析 MGs 在失效过渡过程中的微观结构演变。与拉伸变形相反，二十面体（准二十面体）簇表现出高水平的抗剪切性，并在以剪切为主的变形中保持稳定，这被证实是影响失效过渡的应力状态的结构起源。