Abstract.

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.

Graphical abstract

中文翻译：

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透明合金定向凝固过程中竞争性枝晶的生长：建模和实验。

摘要。

二维（2-D）细胞自动机有限差分法（CA-FDM）模型和原位使用SCN-2wt。％ACE的透明合金进行定向凝固的观察实验，用于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CA技术模拟了柱状树突的生长。溶质扩散通过FDM解决。该模型能够可视化具有相同或不同生长方向的枝晶阵列的形成与不断发展的溶质浓度场之间的相互作用。再现了两个会聚和发散的树突阵列之间的几种树突竞争增长模式。仿真结果与实验结果吻合良好。还进行了仿真，以研究温度梯度和冷却速率对分散的树枝状晶体的生长形态的影响。研究发现，随着温度梯度和冷却速率的增加，不良取向的晶粒在分支晶界处由发达的侧枝产生的三级枝更有可能成为新的初级枝晶臂。

图形概要