Interfaces and interphases in nanoglasses: Surface segregation effects and their implications on structural properties
Interfaces and interphases in nanoglasses: Surface segregation effects and their implications on structural properties
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DOI：
10.1016/j.actamat.2016.05.002
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发表时间：
2016-07-01
期刊：
影响因子：
9.4
通讯作者：
Albe, Karsten
中科院分区：
文献类型：
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作者：
Adjaoud, Omar;Albe, Karsten
最初在惰性气体中凝聚的非晶态纳米颗粒可以通过冷压实来制备金属纳米玻璃。实验发现，纳米玻璃的一个特征是在微观结构中发生原子密度变化，这不能用化学均质材料中界面诱导的拓扑变化来解释。这里我们介绍了分子动力学模拟，它揭示了玻璃-玻璃界面和体积材料之间的成分变化可能是由于初级粒子中已经存在的表面分离效应造成的。通过比较Pd80Si20和Cu64Zr36金属玻璃的结果，我们发现非晶态纳米粒子在玻璃转变为固态之前，在气相中安装了一个不均匀的元素平衡分布。对由化学平衡表面合并产生的平面界面的详细分析表明，玻璃-玻璃界面可以理解为不同组成和短程有序度的界面，其中局部拓扑、自由体积和局部组成密切相关。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
Metallic nanoglasses can be prepared by cold compaction of amorphous nanoparticles initially condensed in inert gas atmosphere. Experimentally, it has been found that a characteristic feature of nanoglasses is the occurrence of atomic density variations within the microstructure, that cannot be explained by interface induced topological variations in a chemically homogeneous material. Here we present molecular dynamics simulations, which reveal that compositional variations between glass-glass interfaces and the volume material can result from surface segregation effects already present in the primary particles. By comparing results for Pd80Si20 and Cu64Zr36 metallic glasses, we show that amorphous nanoparticles install an inhomogenous elemental equilibrium distribution in the gas phase before they undergo the glass transition into the solid state. A detailed analysis of planar interfaces generated by merging chemically equilibrated surfaces shows that glass-glass interfaces can be understood as interphases of different composition and short-range order, where the local topology, free volume and local composition are intimately linked. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.