Grain Size Dependence of Creep in Nanocrystalline Copper by Molecular Dynamics
Grain Size Dependence of Creep in Nanocrystalline Copper by Molecular Dynamics
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DOI：
10.2320/matertrans.md201122
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发表时间：
2012-01-01
影响因子：
1.2
通讯作者：
Ogata, Shigenobu
中科院分区：
文献类型：
--
作者：
Wang, Yun-Jiang;Ishii, Akio;Ogata, Shigenobu
蠕变的晶粒尺寸依赖性是理解纳米金属塑性变形机制的关键。本文采用分子动力学方法研究了纳米晶铜蠕变过程中应力诱导的晶粒尺寸指数转变。晶粒尺寸指数随应力的增加而增加，在某一临界应力后减小。推导出的晶粒尺寸指数与低应力下扩散和晶界滑动蠕变的实验结果一致。而位错形核蠕变的晶粒尺寸指数随应力的增加而减小，这与常规材料的结果相反。本文提出了位错形核控制蠕变的本构方程，用以解释蠕变随应力变化的晶粒尺寸依赖性。[doi：10.2320/matertrans.MD201122]
The grain size dependence of creep is critical to understand the plastic deformation mechanism of nanoscale metals. Here we used molecular dynamics to study the stress-induced grain size exponent transition in creep of nanocrystalline copper. The grain size exponent was found to initially increase with increasing stress, then decrease after some critical stress. The derived grain size exponents are in agreement with experimental results for diffusional and grain boundary sliding creep at low stress. While, the founded decreasing grain size exponent with increasing stress for dislocation nucleation creep in nanocrystal is in contrast with conventional materials. We propose a constitutive equation for dislocation nucleation govemed creep in nanocrystal to explain its grain size dependence transition with stress. [doi: 10.2320/matertrans.MD201122]