Grain boundary model in phase-field simulation during microstructure evolution in solid states is discussed based on the way to express grain boundary and its physical background. The effects of different values of simulation parameters on feature of grain boundary in the phase field model are investigated systematically and a new conception of grain boundary range is suggested based on the simulation results of recrystallization of AZ31 magnesium alloy. The gradient range of the order parameter expresses the boundary range, whose physical meaning is found to be the range of grain boundary energy distribution across the boundary. The range is also corresponding to the segregation range of alloying elements around the boundary. It is shown that the gradient parameter determines the boundary range but the grain boundary energy is determined by both the gradient parameter and the coupling parameter. The effect of the boundary range value on microstructure feature is examined by simulating the recrystallization of the alloy. The simulation results are consistent well with reported experimental measurements when the boundary range has a value of 1. 18 μm. Grain growth phase-field simulation in industrial space and time scale is realized for the first time using the new model developed by introducing the new conception of the grain boundary range.%讨论了当前固态组织演变过程的相场法模拟模型,论证了相场法中界面的概念以及模型中界面的各种处理方法,以AZ31镁合金再结晶系统为例,研究了模型参数取值对界面特征的影响,提出了晶界作用域的概念,阐述了晶界作用域就是相场模型中界面处有序化变量的变化范围,其物理意义是界面能量的分布范围,并对应于成分界面偏析的范围.模拟得出,晶界作用域宽度主要由梯度项系数决定,晶界能则由梯度项系数和耦合项系数共同决定.对于AZ31镁合金,模拟研究了晶界作用域宽度取值的合理性和对显微组织影响的关系,得出取值为1.18μm时,模拟符合实验结果.引入界面作用域的新概念后,利用本模型首次实现了相场法晶粒长大的真实空间、时间的工业尺度的模拟.
展开▼
