Influence of grain size on deformation mechanisms: an extension to nanocrystalline materials
Influence of grain size on deformation mechanisms: an extension to nanocrystalline materials
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DOI：
10.1016/j.msea.2005.05.111
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发表时间：
2005-11
期刊：
影响因子：
6.4
通讯作者：
Yuntian Zhu;T. Langdon
中科院分区：
文献类型：
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作者：
Yuntian Zhu;T. Langdon
粗晶多晶材料的变形机制现在已经得到了相当好的理解。主要变形过程与位错的晶内运动有关，无论是通过低温下的晶体学滑移，还是通过高温下位错攀移和滑移的组合。晶粒间过程在具有小晶粒尺寸的多晶材料中变得重要，包括应力导向的空位扩散和晶界滑动。它已被证明使用分子动力学模拟，并在实验中证实，不同的过程可能变得重要时，晶粒尺寸减小到纳米级。在晶粒尺寸为10- 50 nm时，来自晶界的部分位错发射成为主导过程，这导致即使在具有高层错能的材料（例如铝）中也形成变形孪晶。在低温下，晶粒尺寸小于10 nm时，晶界滑动也成为主导。本文研究了晶粒尺寸对多晶材料变形机制的影响，特别强调了在纳米晶水平上变得重要的新机制。
The deformation mechanisms occurring in coarse-grained polycrystalline materials are now understood reasonably well. The primary deformation processes are associated with the intragranular movement of dislocations either through crystallographic slip at low temperatures or through a combination of dislocation climb and glide at high temperatures. Intergranular processes become important in polycrystalline materials with small grain sizes including stress-directed vacancy diffusion and grain boundary sliding. It has been shown using molecular dynamic simulations, and confirmed in experiments, that different processes may become important when the grain size is reduced to the nanometer level. Partial dislocation emission from grain boundaries becomes a dominant process at grain sizes of 10–50nm and this leads to the formation of deformation twins even in materials with high stacking-fault energies such as aluminum. Grain boundary sliding also becomes dominant at grain sizes below ∼10nm at low temperatures. This paper examines the influence of grain size on the deformation mechanisms in polycrystalline materials with special emphasis on the new mechanisms that become important at the nanocrystalline level.