Deformation-mechanism map for nanocrystalline metals by molecular-dynamics simulation
Deformation-mechanism map for nanocrystalline metals by molecular-dynamics simulation
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DOI：
10.1038/nmat1035
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发表时间：
2004-01-01
期刊：
影响因子：
41.2
通讯作者：
Gleiter, H
中科院分区：
文献类型：
--
作者：
Yamakov, V;Wolf, D;Gleiter, H
分子动力学模拟最近已被用来阐明过渡与减少晶粒尺寸从位错为基础的晶界为基础的变形机制，在纳米晶f.c.c.金属.变形机制的这种转变导致在晶粒尺寸（“最强尺寸”）处的最大屈服强度，该晶粒尺寸强烈地依赖于层错能、金属的弹性性质和所施加应力的大小。在这里，通过探索在这个交叉的堆垛层错能的作用，我们阐明了如何从晶界形核的扩展位错的大小影响的机械行为。建立在这些模拟暴露的变形的基本物理，我们提出了一个二维应力晶粒尺寸变形机制地图的纳米晶f.c.c.的机械行为。低温下的金属该地图捕捉这种转变的变形机制和相关的机械行为与晶粒尺寸减小，以及其依赖于堆垛层错能，材料的弹性性能，和施加的应力水平。
Molecular-dynamics simulations have recently been used to elucidate the transition with decreasing grain size from a dislocation-based to a grain-boundary-based deformation mechanism in nanocrystalline f.c.c. metals. This transition in the deformation mechanism results in a maximum yield strength at a grain size (the 'strongest size') that depends strongly on the stacking-fault energy, the elastic properties of the metal, and the magnitude of the applied stress. Here, by exploring the role of the stacking-fault energy in this crossover, we elucidate how the size of the extended dislocations nucleated from the grain boundaries affects the mechanical behaviour. Building on the fundamental physics of deformation as exposed by these simulations, we propose a two-dimensional stress-grain size deformation-mechanism map for the mechanical behaviour of nanocrystalline f.c.c. metals at low temperature. The map captures this transition in both the deformation mechanism and the related mechanical behaviour with decreasing grain size, as well as its dependence on the stacking-fault energy, the elastic properties of the material, and the applied stress level.