材料期刊网

采用相场法模拟了Fe--0.5%C合金等温凝固过程中单个枝晶和多个枝晶的生长, 研究了过冷度、各向异性、界面厚度、晶体取向以及扰动对枝晶形貌的影响, 获得了具有二次分枝的枝晶形貌, 再现了枝晶生长过程及枝晶臂之间的竞争生长. 模拟结果表明: 凝固过程中存在溶质富集和枝晶偏析, 枝晶主干溶质浓度最低, 枝晶臂之间的液相浓度最高. 随着过冷度的增大, 枝晶生长加快且分枝发达; 界面厚度直接影响枝晶的生长速度; 各向异性影响枝晶的形态; 晶体取向与坐标轴方向一致时枝晶优先生长；扰动的加入导致枝晶分枝的形成.

The evolution of a single dendrite growth and the morphology of multi–dendrite during isothermal solidification of Fe–0.5%C alloy are simulated using phase field method. The effects of supercooling, anisotropy of crystal, interface thickness and crystal orientation as well as the noise on the dendritic morphology are studied. The results illustrate that the morphology of the dendrite is composed of the primary and secondary arms. The process of the dendrite growth and the competition between the dendrite arms are reproduced during solidification. The solute enrichment and the dendrite segregation occur during solidification. The primary arms have the lowest concentration, but the regions between the arms have the highest concentration because of the build–up of solute. With the increment of supercooling, the dendrite grows quickly and the branches are developed. The interface thickness impacts the growth velocity of dendrite. The anisotropy of the crystal exerts an influence on the dendritic morphology. The dendrite grows preferentially when the crystal orientation is consistent with the coordinate axis. The noise leads to the development of the dendritic branches.