For this study, the effects of thermal annealing and compressive strain rate on the complexity of the serration behavior in a Zr-based bulk metallic glass (BMG) was investigated. Here, as-cast and thermally-annealed (300 °C, 1 week) Zr52.5Cu17.9Ni14.6Al10Ti5 BMG underwent room-temperature compression tests in the unconstrained condition at strain rates of 2 × 10−5 s−1 and 2 × 10−4 s−1. The complexity of the serrated flow was determined, using the refined composite multiscale entropy technique. Nanoindentation testing and X-ray diffraction characterization were performed to assess the changes in the microstructure and mechanical properties of the BMG that occurred during annealing. The results indicated that the BMG did not crystallize during annealing in the prescribed heating condition. Nanoindentation tests revealed that annealing led to a significant increase in the depth-dependent nanoindentation hardness and Young’s modulus, which were attributed to the structural relaxation in the glass. Furthermore, both annealing and an increased strain rate resulted in a marked enhancement in the complexity of the serrated flow during compression. It was concluded that the increase in the sample entropy with increasing strain rate is related to an increase in the number of defect interactions during the serrated flow.

中文翻译：

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Zr基块状金属玻璃缺陷相互作用与锯齿动力学的关系

在本研究中，研究了热退火和压缩应变速率对 Zr 基块状金属玻璃 (BMG) 锯齿行为复杂性的影响。在这里，铸态和热退火（300 °C，1 周）Zr52.5Cu17.9Ni14.6Al10Ti5 BMG 在无约束条件下以 2 × 10−5 s−1 和 2 × 10-4 秒-1。使用改进的复合多尺度熵技术确定了锯齿流的复杂性。进行纳米压痕测试和 X 射线衍射表征以评估退火过程中 BMG 的微观结构和机械性能的变化。结果表明，在规定的加热条件下退火过程中，BMG 没有结晶。纳米压痕测试表明，退火导致与深度相关的纳米压痕硬度和杨氏模量显着增加，这归因于玻璃中的结构松弛。此外，退火和增加的应变率都导致压缩过程中锯齿状流动的复杂性显着增加。得出的结论是，随着应变速率的增加，样品熵的增加与锯齿状流动过程中缺陷相互作用数量的增加有关。