Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation.
Local microstructure evolution at shear bands in metallic glasses with nanoscale phase separation.
复制标题
具有纳米级相分离的金属玻璃剪切带处的局部微观结构演化
DOI：
10.1038/srep25832
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发表时间：
2016-05-16
影响因子：
4.6
通讯作者：
Greer AL
中科院分区：
文献类型：
--
作者：
He J;Kaban I;Mattern N;Song K;Sun B;Zhao J;Kim do H;Eckert J;Greer AL
在室温下，金属玻璃的塑性流动强烈地局限于剪切带中，这是金属玻璃塑性变形的一个重要特征。尽管剪切带的重要性已经明确，并且已经进行了数十年的研究，但剪切带的形成条件、结构演化和增殖机制仍然存在争议。在这项工作中，我们调查的剪切带在新的相分离的大块MG含有玻璃纳米球和压缩下表现出特殊的塑性的局部条件。结果发现，剪切带内的玻璃态纳米球溶解通过机械混合驱动的尖锐的应变局部化，而那些附近的基体中的Ostwald熟化由于原子的流动性增加而变粗。实验结果表明，在剪切带周围存在一个影响区。这一区域可能是由带之间基体中的低应变塑性变形引起的。这些结果表明，所测量的性能变化不仅源于剪切带本身，而且还来自相邻基体中的受影响区域。这项工作揭示了直接可视化的变形相关的影响，特别是增加原子的流动性，在剪切带周围的区域。
At room temperature, plastic flow of metallic glasses (MGs) is sharply localized in shear bands, which are a key feature of the plastic deformation in MGs. Despite their clear importance and decades of study, the conditions for formation of shear bands, their structural evolution and multiplication mechanism are still under debate. In this work, we investigate the local conditions at shear bands in new phase-separated bulk MGs containing glassy nanospheres and exhibiting exceptional plasticity under compression. It is found that the glassy nanospheres within the shear band dissolve through mechanical mixing driven by the sharp strain localization there, while those nearby in the matrix coarsen by Ostwald ripening due to the increased atomic mobility. The experimental evidence demonstrates that there exists an affected zone around the shear band. This zone may arise from low-strain plastic deformation in the matrix between the bands. These results suggest that measured property changes originate not only from the shear bands themselves, but also from the affected zones in the adjacent matrix. This work sheds light on direct visualization of deformation-related effects, in particular increased atomic mobility, in the region around shear bands.