晶粒生长的双区域动力学蒙特卡洛模拟

Bi-region Kinetic Monte Carlo Simulation of Grain Growth

现有的动力学蒙特卡洛方法模拟晶粒生长过程的结果与理论计算值之间大多存在偏差,其中重要的原因是现有方法大多采用只适用于计算小角度晶界Read-Shockley公式。针对此问题,本文提出了一种对大、小角度晶界都适用的双区域动力学蒙特卡洛模拟方法。该方法通过基于势函数的格点能量获得取向概率,从而避免使用Read-Shockley公式。为了解决引入势函数导致计算量大的问题,划分动力学蒙特卡洛的单区域结构为晶界区域和非晶界区域的双区域结构,并将势函数的计算限制在晶界区内,从而减少了计算时间。实验模拟结果表明:与传统的和改进的动力学蒙特卡洛方法相比,双区域动力学蒙特卡洛方法的微观组织演变更符合晶粒生长特征,晶粒生长指数也更接近理论值。

There exist deviations between the results of most kinetic Monte Carlo （kMC） simulation of grain growth and the theoretical value of grain growth. An important reason is that the Read-Shockley formulation in most kMC simulation is only suitable for the computation of small-angle grain boundary. Aiming at this problem,a bi-region kMC method is proposed in this paper,which handles both situation of small-angle grain boundary and large-angle grain boundary. In the proposed method, the transition probability of orientation number is obtained using lattice energy based on potential functions, not using Read-Shockley formula. In order to solve the large computational problem caused by introducing potential functions,kMC single-region structure of traditional dynamics is divided into two regions.the one without grain boundary and the one with the grain boundary. Due to potential function computation only used in the region of grain boundary, the computing time is reduced. Experiment results show that the micro-structure evolution of bi-region kMC method is more consistent with the feature of grain growth than that of existing traditional and improved kMC,and the grain growth exponent is closer to the theoretical value than that of existing kMC.