Grain rotation by dislocation climb in a finite-size grain boundary
Grain rotation by dislocation climb in a finite-size grain boundary
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DOI：
10.1016/j.actamat.2012.09.014
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发表时间：
2012-12
期刊：
影响因子：
9.4
通讯作者：
D. Bachurin;A. Nazarov;J. Weissmüller
中科院分区：
文献类型：
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作者：
D. Bachurin;A. Nazarov;J. Weissmüller
本文用离散位错方法研究了倾斜晶界双晶体中刃型位错壁的弛豫过程，研究了倾斜晶界双晶体中的晶粒旋转动力学。边界在一个方向上无限延伸，在正交方向上有限。弛豫过程的数值模拟通过求解位错的运动方程，假设攀登扩散输运在边界平面。令人惊讶的是，我们发现边界永远不会旋转到巧合。相反，最终的状态是一个亚稳态阵列与18个位错，因此，与有限的取向差，取决于边界长度和伯格斯矢量。所有少于18个位错的晶界也是亚稳的。弛豫时间达到亚稳态配置被发现是成比例的位错的数量的对数和边界的长度的立方。我们给出了一个关键的讨论图像力的论点，根据早先的工作粮食旋转，并验证目前的图像力的分析不满足自由表面的边界条件。研究结果对纳米粒子在衬底上的旋转动力学以及金属薄膜中晶粒和亚晶粒边界的稳定性具有重要意义。
We investigate the kinetics of grain rotation in a bicrystal with a tilt grain boundary by studying the relaxation of an edge dislocation wall in a discrete-dislocation approach. The boundary is infinitely extended in one direction and of finite size in the orthogonal one. The relaxation process is simulated numerically by solving the equations of motion of the dislocations, assuming climb by diffusive transport in the boundary plane. Surprisingly, we find that boundaries never rotate all the way into coincidence. Instead, the final state is a metastable array with 18 dislocations and, hence, with a finite misorientation that depends on the boundary length and the Burgers vector. All boundaries with fewer than 18 dislocations are also metastable. The relaxation time to reach the metastable configuration is found to be proportional to the logarithm of the number of dislocations and to the cube of the length of the boundary. We give a critical discussion of image force arguments that underlie earlier work on grain rotation, and verify that the present analysis of image forces does satisfy the boundary conditions at the free surfaces. The results have implications for the kinetics of rotation of nanoparticles on a substrate and for the stability of grain and subgrain boundaries in thin metal films.