Atomic-scale homogeneous plastic flow beyond near-theoretical yield stress in a metallic glass
Atomic-scale homogeneous plastic flow beyond near-theoretical yield stress in a metallic glass
复制标题
DOI：
10.1038/s43246-021-00124-3
复制
发表时间：
2021-02
影响因子：
7.8
通讯作者：
Jiaxin Yu;A. Datye;Zheng Chen;Chao Zhou;Omur E. Dagdeviren;J. Schroers;U. Schwarz
中科院分区：
文献类型：
--
作者：
Jiaxin Yu;A. Datye;Zheng Chen;Chao Zhou;Omur E. Dagdeviren;J. Schroers;U. Schwarz
由于进行原子尺度塑性变形实验以直接了解潜在的基本变形机制的困难，大块金属玻璃在室温下屈服的开始和相关的原子尺度塑性流动行为尚未完全了解。在这里，我们通过将独特的样品制备方法与基于原子力显微镜的压痕相结合来克服这些限制，该方法可以研究含有大约1000个原子的铂基大块金属玻璃的屈服应力，屈服开始和原子尺度的塑性流动。观察到的屈服应力明显高于传统的纳米压痕测试，超过了当前将屈服应力与测试体积相关的模型的预测；随后的流动被确定为均匀的，没有表现出集体剪切局部化或加载速率依赖。总的来说，由于自由体积的波动而引起的玻璃性质的变化比以前认为的要小得多。
The onset of yielding and the related atomic-scale plastic flow behavior of bulk metallic glasses at room temperature have not been fully understood due to the difficulty in performing the atomic-scale plastic deformation experiments needed to gain direct insight into the underlying fundamental deformation mechanisms. Here we overcome these limitations by combining a unique sample preparation method with atomic force microscopy-based indentation, which allows study of the yield stress, onset of yielding, and atomic-scale plastic flow of a platinum-based bulk metallic glass in volumes containing as little as approximately 1000 atoms. Yield stresses markedly higher than in conventional nanoindentation testing were observed, surpassing predictions from current models that relate yield stress to tested volumes; subsequent flow was then established to be homogeneous without exhibiting collective shear localization or loading rate dependence. Overall, variations in glass properties due to fluctuations of free volume are found to be much smaller than previously suggested.