Dislocation Climb Models from Atomistic Scheme to Dislocation Dynamics
Dislocation Climb Models from Atomistic Scheme to Dislocation Dynamics
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DOI：
10.1016/j.jmps.2016.11.012
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发表时间：
2016-07
影响因子：
5.3
通讯作者：
Xiaohua Niu;T. Luo;Jianfeng Lu;Y. Xiang
中科院分区：
文献类型：
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作者：
Xiaohua Niu;T. Luo;Jianfeng Lu;Y. Xiang
我们从原子尺度上的随机模型出发，通过尺度放大，建立了空位辅助位错攀移的介观位错动力学模型。我们的模型结合了微观机制（i）体扩散的空缺，（ii）体和位错核心之间的空缺交换动力学，（iii）空位管扩散沿着的位错核心，和（iv）空缺的附着-脱离动力学在凹凸导致凹凸运动。我们的介观模型由空位体扩散方程和位错攀移速度公式组成。这些微观机制的影响被纳入由罗宾边界条件附近的位错的体扩散方程和一个新的贡献，由于空位管扩散驱动的应力变化沿沿着的位错攀移速度。我们的攀登公式是能够定量地描述平移的棱柱环在低温时，体扩散可以忽略不计。利用这个新的提法，我们推导出解析公式的直刃位错和棱柱形的圆形回路的爬升速度。我们的位错攀移公式可以实现在位错动力学模拟，将所有上述四个微观机制的位错攀移。
We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk diffusion equation and a dislocation climb velocity formula. The effects of these microscopic mechanisms are incorporated by a Robin boundary condition near the dislocations for the bulk diffusion equation and a new contribution in the dislocation climb velocity due to vacancy pipe diffusion driven by the stress variation along the dislocation. Our climb formulation is able to quantitatively describe the translation of prismatic loops at low temperatures when the bulk diffusion is negligible. Using this new formulation, we derive analytical formulas for the climb velocity of a straight edge dislocation and a prismatic circular loop. Our dislocation climb formulation can be implemented in dislocation dynamics simulations to incorporate all the above four microscopic mechanisms of dislocation climb.