枝晶(数学)
扩散
材料科学
过冷
有效扩散系数
扩散层
相(物质)
热力学
半径
扩散方程
定向凝固
谐振器耦合系数
扩散过程
晶界扩散系数
化学
微观结构
图层(电子)
复合材料
物理
有机化学
服务(商务)
创新扩散
经济
谐振器
磁共振成像
经济
放射科
医学
知识管理
光电子学
晶界
计算机科学
计算机安全
数学
几何学
作者
San‐Yan Chu,Chunwen Guo,Zhijun Wang,Junjie Li,Jincheng Wang
出处
期刊:Chinese Physics
[Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences]
日期:2019-01-01
卷期号:68 (16): 166401-166401
被引量:1
标识
DOI:10.7498/aps.68.20190603
摘要
Solute diffusion is an important process that determines the dendrite growth during solidification. The theoretical model generally simplifies the solute diffusion coefficient in liquid phase into a constant. Nevertheless, the composition of the boundary layer changes greatly in the solidification process, the diffusion coefficient will no longer be a constant and is dependent on concentration. In this paper, the quantitative phase field model is used to simulate the effect of concentration-dependent diffusion coefficient on dendrite growth in directional solidification. In the model, the concentration-dependent diffusion process is investigated by coupling the concentration-dependent diffusion coefficient in the liquid solute diffusion equation. A series of simulation results confirms that the concentration-dependent diffusion process has a significant effect on the dendrite growth. The results show that the increase of the coupling intensity of solute concentration will enhance the diffusion of solute in the mushy zone between primary dendrites to the dendrite tip, resulting in the increase of solute enrichment at the dendrite tip, thereby increasing the tip undercooling. The variation of diffusion coefficient in liquid phase has little effect on the tip radius of dendrite, and the simulation results are in good agreement with those from the theoretical model. Moreover, the amplitude of dendritic side branches decreases with the increase of solute diffusion coefficient. In the study of dendrite arrays, it is found that the concentration-dependent diffusion coefficient increases the primary spacing and reduce the tip position. The results of this study indicate that for a system with a concentration-dependent coefficient significantly, the effect of concentration-dependent diffusion on tip undercooling and side branches should be considered in the quantitative and experimental verification of the existing model.
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