Hu Mengdan, Sun Chang, Fang Hui, Zhu Mingfang
Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, 211189, Nanjing, P.R. China.
Eur Phys J E Soft Matter. 2020 Mar 2;43(3):16. doi: 10.1140/epje/i2020-11941-4.
A two-dimensional (2-D) cellular automaton-finite difference method (CA-FDM) model and in situ observation experiments of directional solidification using a transparent alloy of SCN-2wt.% ACE are employed to investigate various microstructural evolution of columnar dendrites during directional solidification. In the present model, the growth of columnar dendrites is simulated using a CA technique. The solute diffusion is solved using the FDM. The model is capable of visualizing the interaction between the formation of dendrite arrays with identical or different growth orientations, and the evolving solute concentration field. Several dendritic competitive growth modes between two converging and diverging dendrite arrays are reproduced. The simulation results agree well with the experimental observations. The simulations are also performed to study the effects of temperature gradient and cooling rate on the growth morphology of diverging dendrites. It is found that with the increase of temperature gradient and cooling rate, the tertiary branches produced from the well-developed side branches of the unfavorably oriented grain at the divergent grain boundaries are more likely to become the new primary dendrite arms.
采用二维（2-D）细胞自动机-有限差分法（CA-FDM）模型以及使用SCN-2wt.% ACE透明合金进行定向凝固的原位观察实验，来研究定向凝固过程中柱状枝晶的各种微观结构演变。在本模型中，使用细胞自动机技术模拟柱状枝晶的生长。用有限差分法求解溶质扩散问题。该模型能够可视化具有相同或不同生长取向的枝晶阵列形成与不断演变的溶质浓度场之间的相互作用。再现了两个汇聚和发散枝晶阵列之间的几种枝晶竞争生长模式。模拟结果与实验观察结果吻合良好。还进行了模拟以研究温度梯度和冷却速率对发散枝晶生长形态的影响。结果发现，随着温度梯度和冷却速率的增加，在发散晶界处取向不利晶粒发育良好的侧枝产生的三次枝晶更有可能成为新的一次枝晶臂。
