Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction
Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction
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DOI：
10.1039/c6cp03261c
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发表时间：
2017-03-28
影响因子：
3.3
通讯作者：
Christie, Jamieson K.
中科院分区：
文献类型：
--
作者：
Gulenko, Anastasia;Chungong, Louis Forto;Christie, Jamieson K.
我们使用经典的分子动力学模拟和中子衍射相结合，以确定五种不同的Mg-Zn-Ca大块金属玻璃的原子结构，覆盖了一系列的组合物，植入体外时具有显著不同的行为。从计算机模拟得到的结构与实验结果有很好的一致性。键长和总相关函数不随组成而显著变化。锌和钙的键合表现出组成之间的差异：Zn-Ca键长的分布随着Zn含量的增加而变窄，并且Zn和Ca避免彼此键合的偏好变得不那么强，并且对于Zn-Ca，转变为正偏好彼此键合。这种转变发生在大约相同的Zn含量下，在该Zn含量下，注入行为发生变化，暗示可能的结构连接。还发现Voronoi多面体的分布非常广泛，并且这种分布随着锌含量的增加而变宽。通常用来描述大块金属玻璃结构的有效团簇堆积模型不能很好地描述这些系统。
We use a combination of classical molecular dynamics simulation and neutron diffraction to identify the atomic structure of five different Mg-Zn-Ca bulk metallic glasses, covering a range of compositions with substantially different behaviour when implanted in vitro. There is very good agreement between the structures obtained from computer simulation and those found experimentally. Bond lengths and the total correlation function do not change significantly with composition. The zinc and calcium bonding shows differences between composition: the distribution of Zn-Ca bond lengths becomes narrower with increasing Zn content, and the preference for Zn and Ca to avoid bonding to themselves or each other becomes less strong, and, for Zn-Ca, transforms into a positive preference to bond to each other. This transition occurs at about the same Zn content at which the behaviour on implantation changes, hinting at a possible structural connection. A very broad distribution of Voronoi polyhedra are also found, and this distribution broadens with increasing Zn content. The efficient cluster packing model, which is often used to describe the structure of bulk metallic glasses, was found not to describe these systems well.