Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass
Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass
复制标题
Cu-Zr金属玻璃热回复过程中与局域原子有序相关的非均匀结构变化
DOI：
10.1080/14686996.2019.1624140
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发表时间：
2019-06
影响因子：
5.5
通讯作者：
M. Wakeda;J. Saida
中科院分区：
文献类型：
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作者：
M. Wakeda;J. Saida
摘要 在这项研究中，我们研究了金属玻璃热过程（热再生）中结构激发的原子机制。在分子动力学框架中，Cu-Zr金属玻璃通过在高于玻璃化转变温度的温度下进行等温热处理，然后快速冷却组成的热处理过程得以恢复活力。对局部重排、势能和几何结构的原子分析揭示了再生过程中与局部原子顺序相关的结构变化。在热再生热处理的早期阶段，结构激发表现出纳米尺度的空间异质性。更激发的区域（即具有较大原子非仿射和仿射变换的区域）表现出低序结构，反之亦然，这意味着局部结构激发与局部原子有序显着相关。随着上述等温过程的进行，结构激发由部分激发转变为整体激发。尽管再生降低了有序结构，但计算结果表明新有序局部结构和新无序局部结构的形成与热过程中的局部结构激发和原子动力学相关。这些结果表明，再生过程的异质结构演化导致金属玻璃微观结构中局部原子有序度的重新分布。图文摘要
ABSTRACT In this study, we investigated the atomistic mechanism of structural excitation in a thermal process (thermal rejuvenation) of metallic glass. In a molecular dynamics framework, Cu-Zr metallic glass was rejuvenated by a thermal process composed of an isothermal heat treatment at a temperature above the glass transition temperature , followed by fast cooling. Atomistic analyses of the local rearrangement, potential energy, and geometrical structure revealed structural changes correlating to the local atomic order in the rejuvenation process. In the early stage of the heat treatment for thermal rejuvenation, the structural excitation exhibited spatial heterogeneity at the nanometer scale. More-excited regions (i.e., regions with large atomic non-affine and affine transformations) exhibited low-ordered structures and vice versa, implying that the local structural excitation is significantly correlated with the local atomic order. The structural excitation transitioned from partial to whole as the isothermal process proceeded above . Although rejuvenation decreased the ordered structure, the calculation results suggested the formation of newly ordered local structures and newly disordered local structures correlated to local structural excitations and atomic dynamics in the thermal process. These results indicate that the heterogeneous structure evolution of the rejuvenation process induces a redistribution of the local atomic order in the microstructure of metallic glasses. Graphical abstract