Abstract In this study, finite element analyses of Mode I loading of stationary cracks in in-situ bulk metallic glass composites (BMGCs) are performed under plane strain, small scale yielding (SSY) conditions. In the first part of this work, a thermodynamically consistent finite strain constitutive theory for BMGCs is employed to represent the entire domain. In this homogenized model, the soft crystalline dendrites are considered to obey J 2 flow theory of plasticity with isotropic power law hardening, while the bulk metallic glass (BMG) matrix is taken to follow a free-volume based constitutive model. The effects of volume fraction V f and hardening of the crystalline dendrites on the macroscopic stress and plastic strain fields are systematically studied. The predicted trend of the fracture toughness versus V f corroborates well with experiments. In the second part, multi-scale SSY analyses are performed, with discrete soft dendrites in the BMG matrix close to notch tip explicitly simulated, while the surrounding region is represented by the homogenized BMGC model. It is found that low strength and/or low hardening dendrites with high V f dissipate more plastic work in the neighborhood of the notch tip, thereby shielding the relatively brittle BMG matrix.

中文翻译：

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模式Ⅰ、小规模屈服条件下块状金属玻璃复合材料固定裂纹的数值研究

摘要 在本研究中，在平面应变、小规模屈服 (SSY) 条件下对原位块状金属玻璃复合材料 (BMGC) 中的固定裂纹的 I 型加载进行了有限元分析。在这项工作的第一部分，BMGCs 的热力学一致的有限应变本构理论被用来表示整个域。在这个均质模型中，软结晶枝晶被认为遵循具有各向同性幂律硬化的 J 2 塑性流动理论，而块状金属玻璃 (BMG) 基体被认为遵循基于自由体积的本构模型。系统地研究了体积分数V f 和结晶枝晶硬化对宏观应力场和塑性应变场的影响。断裂韧性与 V f 的预测趋势很好地证实了实验。在第二部分中，进行了多尺度 SSY 分析，BMG 矩阵中的离散软树突靠近缺口尖端明确模拟，而周围区域由均质 BMGC 模型表示。发现具有高 V f 的低强度和/或低硬化枝晶在缺口尖端附近消散更多的塑性功，从而屏蔽相对脆性的 BMG 基体。