Abstract Deeply-notched metallic glasses can achieve significantly enhanced nominal tensile strain and strength under tension, and show the characteristics of dimples and “cup-and-cone” morphology on the fractographs. It has been expected that this deep-notch enhancement effect is resulted from the suppressed shear banding. In this study, we provided another interpretation for this effect through stress/strain field analyses based on the ellipse criterion. The results revealed the existence of relatively low but highly dispersed stress/strain instead of highly enhanced and localized stress/strain in deeply-notched metallic glasses, and therefore the actual stress is much lower than the nominal value. Owing to the positive third principal stress condition, the failure angle predicted by the ellipse criterion shifted from 45° at the edge of the notch to 90° at the center of the specimen, which was consistent with the “cup-and-cone” fracture morphology. These findings clarify the very high nominal stress/strain and special fracture process in deeply-notched metallic glasses. Our work provides a useful method to predict the shear-to-tensile failure mode transition of metallic glasses under complex loading conditions.

中文翻译：

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了解深缺口金属玻璃的拉伸断裂

摘要 深缺口金属玻璃在拉伸作用下可以显着提高标称拉伸应变和强度，并在断口图上表现出凹坑和“杯锥”形貌特征。预计这种深缺口增强效果是由抑制剪切带引起的。在这项研究中，我们通过基于椭圆准则的应力/应变场分析为这种效应提供了另一种解释。结果表明，深缺口金属玻璃中存在相对较低但高度分散的应力/应变，而不是高度增强的局部应力/应变，因此实际应力远低于标称值。由于正的第三主应力​​条件，椭圆准则预测的破坏角从缺口边缘的 45° 转变为试样中心的 90°，这与“杯锥”断裂形态一致。这些发现阐明了深缺口金属玻璃中非常高的标称应力/应变和特殊的断裂过程。我们的工作提供了一种有用的方法来预测复杂载荷条件下金属玻璃的剪切到拉伸破坏模式的转变。