相场法模拟第二相颗粒对柱状晶定向生长的影响

目的]第二相颗粒的存在能影响晶粒的长大,提高材料的力学性能,因而我们用计算机模拟了含第二相颗粒的镍基合金材料在再结晶后的定向退火过程中的柱状晶生长。方法]在相场法的基础上引入一个温度控制晶界运动的二维平面退火模型,使用该模型对含第二相颗粒的样品进行定向退火处理,观察退火过程中组织形貌的变化,并从第二相颗粒的含量和位置两个方面来讨论退火过程中第二相颗粒对柱状晶组织生长的影响,通过对柱状晶长宽比的统计来反应这些变化。结果]定向退火处理可产生柱状晶结构;弥散分布的第二相颗粒的存在不利于柱状晶生长,并且含量越高柱状晶越粗,长宽比越小。结论]第二相颗粒位置可以改变柱状晶晶界的形成方向,间距可以影响长宽比的大小,颗粒间的横向间距和纵向间距都存在一个临界值使柱状晶的长宽比最大。

Phase Field Method Simulation of Directional Growth of Grain with Second Phase Particles

Objective] The second particle has effect on the grain growth. In order to improve the mechanical properties of materials, we use computer to simulate the growth of the direction columnar of Ni-based alloy in the process of annealing after recrystallizing.Methods] Based on the phase field method, a two-dimensional annealing model for temperature controlled grain boundary motion is introduced to treat the samples with the second phase particles, and the changes of microstructure were observed. The effect of second phase particles on the growth of columnar crystal structure was discussed from two aspects:The content and the position of the second phase particles, and counting the aspect ratio to reflect the change of the columnar crystals.Results] The directional annealing process can produce columnar crystal structure. Second phase particles of dispersion distribution are not conducive to the growth of columnar crystals, and the higher the content, the more the columnar crystal, the smaller the aspect ratio.Conclusion] The position of second phase particles can change the columnar crystal formation direction, and there is a critical value in the horizontal and vertical spacing between the particles, which guarantees the aspect ratio of columnar crystals to reach the largest.