Deformation mechanism crossover and mechanical behaviour in nanocrystalline materials
Deformation mechanism crossover and mechanical behaviour in nanocrystalline materials
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DOI：
10.1080/09500830031000120891
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发表时间：
2003-06
影响因子：
1.2
通讯作者：
V. Yamakov;D. Wolf;S. Phillpot;Amiya K. Mukherjee;H. Gleiter
中科院分区：
文献类型：
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作者：
V. Yamakov;D. Wolf;S. Phillpot;Amiya K. Mukherjee;H. Gleiter
我们使用分子动力学模拟来阐明从位错到晶界为基础的变形机制在纳米晶面心立方金属晶粒尺寸减小的过渡。我们的模拟结果表明，这种交叉是伴随着一个明显的过渡，在材料的机械行为，即，在晶粒尺寸发生交叉（“最强的尺寸”），拉伸伸长率下的应变率经历了一个最小值。这种同时过渡的变形机制和相应的机械行为提供了一个解释实验观察到的交叉纳米晶材料的屈服强度，从霍尔-佩奇硬化到“逆霍尔-佩奇”软化。
We use molecular dynamics simulations to elucidate the transition with decreasing grain size from a dislocation- to a grain-boundary-based deformation mechanism in nanocrystalline fcc metals. Our simulations reveal that this crossover is accompanied by a pronounced transition in the mechanical behaviour of the material; namely, at the grain size where the crossover occurs (the 'strongest size'), the strain rate under tensile elongation goes through a minimum. This simultaneous transition in both the deformation mechanism and the corresponding mechanical behaviour offers an explanation for the experimentally observed crossover in the yield strength of nanocrystalline materials, from Hall-Petch hardening to 'inverse Hall-Petch' softening.