Kinematics of polycrystal deformation by grain boundary sliding
Kinematics of polycrystal deformation by grain boundary sliding
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DOI：
10.1016/j.actamat.2011.03.060
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发表时间：
2011-06
期刊：
影响因子：
9.4
通讯作者：
J. Weissmüller;J. Markmann;M. Grewer;R. Birringer
中科院分区：
文献类型：
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作者：
J. Weissmüller;J. Markmann;M. Grewer;R. Birringer
我们分析了多晶固体的宏观变形，由于在晶界的核心的局部变形事件。中心的结果是一个方程，分解成三个变形模式，即：（i）在大部分的微晶的弹性应变的贡献的有效宏观应变;（ii）位错滑移和攀爬过程的结果;和（iii）在晶界核心的变形事件。后一个过程由位移矢量场的跳跃表示，位移矢量场可以分解为切向（“滑动”）和法向（“拉伸”）分量。晶界介导的变形的相关措施是不是位移跳跃矢量，但晶界不连续张量，取决于位移跳跃和晶界法线的方向。在三重连接处的调节过程对宏观应变没有显著的贡献。通过算例，将该理论应用于晶界处具有过剩滑移柔量的纳米晶材料的有效弹性响应。的预测，特别是对泊松比的大小依赖性，同意最近的纳米晶Pd的实验。Pd中晶界的滑移柔量值为18 pm GPa−1。
We analyze the macroscopic deformation of a polycrystalline solid due to local deformation events in the core of grain boundaries. The central result is an equation that decomposes the effective macroscopic strain into contributions from three deformation modes, namely: (i) the elastic strain in the bulk of the crystallites; (ii) the results of dislocation glide and climb processes; and (iii) the deformation events in the grain boundary core. The latter process is represented by jumps in the displacement vector field that can be decomposed into tangential (“slip”) and normal (“stretch”) components. The relevant measure for the grain-boundary-mediated deformation is not the displacement jump vector but a grain-boundary discontinuity tensor that depends on the displacement jump and on the orientation of the grain boundary normal. Accommodation processes at triple junctions do not contribute significantly to the macroscopic strain. By means of example, the theory is applied to the effective elastic response of nanocrystalline materials with an excess slip compliance at grain boundaries. The predictions, specifically on the size dependence of the Poisson ratio, agree with recent experiments on nanocrystalline Pd. The value of the slip compliance for grain boundaries in Pd is obtained as 18 pm GPa−1.