相场法研究初始微结构对晶粒长大的影响

【目的】研究不同初始微结构对晶粒长大过程及生长动力学的影响。【方法】采用相场法(Phase Field)模拟二维多晶材料中正常晶粒长大及初态分别为柱状和梯度微结构的晶粒长大过程。【结果】正常晶粒长大的相对晶粒尺寸分布具有时间不变性的特点;柱状微结构的长宽比和梯度微结构的梯度指数均直接影响晶粒长大动力学,这两种初始微结构在演化过程中均向均匀等轴微结构转变。【结论】晶粒长大是大晶粒不断吞噬相邻小晶粒的过程;晶界曲率对晶粒长大过程有显著影响,曲率越大,晶粒长大越快。

Phase Field Study on Effect of Initial Microstructure on Grain Growth

Objective]The effects of different initial microstructures on grain growth process and growth dynamics were studied.Methods]The growth processes of normal grain,columnar and graded microstructures in two-dimensional polycrystalline materials were studied by phase field method.Results]The relative normalized grain size distribution of normal grain growth has time-invariant nature,and the aspect ratio of columnar microstructure and gradient index of graded microstructure directly affect grain growth dynamics,while these two kinds of initial microstructures evolve towards uniform and equiaxed microstructures during grain growth.Conclusion]Grain growth is a process in which large grains grow at the expense of their smal-ler neighbours.Grain boundary curvature has a significant influence on the grain growth process,i.e.,the larger the boundary curvature is,the faster the grain grows.