Chemical and topological order in shear bands of Cu64Zr36 and Cu36Zr64 glasses
Chemical and topological order in shear bands of Cu64Zr36 and Cu36Zr64 glasses
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DOI：
10.1063/1.4717748
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发表时间：
2012-05-15
影响因子：
3.2
通讯作者：
Albe, Karsten
中科院分区：
文献类型：
--
作者：
Ritter, Yvonne;Albe, Karsten
用分子动力学方法研究了Cu 64 Zr 36和Cu 36 Zr 64二元金属玻璃中的剪切带，讨论了剪切带的化学和拓扑短程有序性.在这两种玻璃中，剪切带的形成沿着剪切带内过量体积的增加。只有在富铜合金，其中铜为中心的二十面体代表最丰富的拓扑单元，剪切带内的膨胀是有关的二十面体单元的数量减少，而交联度和集群的大小减少时，剪切带的形式。相反，在Cu 36 Zr 64玻璃中，当材料开始屈服并形成剪切带时，没有拓扑特征改变。然而，在剪切带内的两种材料，这是揭示了Cu-Cu和Zr-Zr键的数量增加的化学短程顺序的影响。由于所有结构修饰都是塑性变形的结果，而不是先决条件，因此我们得出结论，不同拓扑特征（例如二十面体单元）的存在并不是剪切带形成的先决条件。(C)2012年美国物理学会。[http：//dx.doi.org/10.1063/1.4717748]
Shear bands in binary Cu64Zr36 and Cu36Zr64 metallic glasses are studied by molecular dynamics simulations with respect to their chemical and topological short range order. In both glasses, shear band formation goes along with an increase in excess volume inside the shear band. Only in the Cu-rich alloy, where Cu-centered icosahedra represent the most abundant topological unit, the dilatation within the shear band is related to a decrease in the number of icosahedral units, while the degree of cross-linking and the cluster size decrease when a shear band forms. In the Cu36Zr64 glass, in contrast, no topological feature changes when the material starts yielding and a shear band is formed. The chemical short range order, however, is affected in both materials within the shear band, which is revealed by an increase in the number of Cu-Cu and Zr-Zr bonds. Since all structural modifications are rather the result of plastic deformation than a pre-requisite, we conclude that the presence of distinct topological features, such as icosahedral units, is not a pre-requisite for shear band formation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4717748]