Cheng Kuiyu, Zhang Liang, Lu Cheng, Tieu Kiet
School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
Sci Rep. 2016 May 3;6:25427. doi: 10.1038/srep25427.
The shear-induced coupled grain boundary motion plays an important role in the deformation of nanocrystalline (NC) materials. It has been known that the atomic structure of the grain boundary (GB) is not necessarily unique for a given set of misorientation and inclination of the boundary plane. However, the effect of the structural multiplicity of the GB on its coupled motion has not been reported. In the present study we investigated the structural multiplicity of the symmetric tilt Σ5(310) boundary in aluminium and its influence on the GB behaviour at a temperature range of 300 K-600 K using molecular dynamic simulations. Two starting atomic configurations were adopted in the simulations which resulted in three different GB structures at different temperatures. Under the applied shear deformation each GB structure exhibited its unique GB behaviour. A dual GB behaviour, namely the transformation of one GB behaviour to another during deformation, was observed for the second starting configuration at a temperature of 500 K. The atomistic mechanisms responsible for these behaviour were analysed in detail. The result of this study implicates a strong relationship between GB structures and their behaviour, and provides a further information of the grain boundary mediated plasticity in nanocrystalline materials.
剪切诱导的耦合晶界运动在纳米晶（NC）材料的变形中起着重要作用。众所周知，对于给定的一组晶界取向差和晶界面倾斜度，晶界（GB）的原子结构不一定是唯一的。然而，晶界结构多样性对其耦合运动的影响尚未见报道。在本研究中，我们使用分子动力学模拟研究了铝中对称倾斜Σ5(310)晶界的结构多样性及其在300 K - 600 K温度范围内对晶界行为的影响。模拟中采用了两种初始原子构型，这导致在不同温度下产生了三种不同的晶界结构。在施加的剪切变形下，每种晶界结构都表现出其独特的晶界行为。对于第二种初始构型，在500 K温度下观察到了双重晶界行为，即在变形过程中一种晶界行为向另一种晶界行为的转变。详细分析了导致这些行为的原子机制。本研究结果表明晶界结构与其行为之间存在密切关系，并为纳米晶材料中晶界介导的塑性提供了进一步的信息。
