Fang Hui, Xue Hua, Zhang Qingyu, Pan Shiyan, Hu Mengdan, Zhu Mingfang
Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, 211189, Nanjing, China.
Shagang School of Iron and Steel, Soochow University, 215137, Suzhou, China.
Eur Phys J E Soft Matter. 2020 Jul 8;43(7):44. doi: 10.1140/epje/i2020-11968-5.
A two-dimensional quantitative cellular automaton (CA) model is employed to simulate dendrite arm fragmentation and dendrite arm coarsening in mushy zones. The phenomenon of dendrite arm fragmentation of an Al-Cu alloy during heating is well represented by the CA simulation, and it is analyzed in detail by comparing the local actual concentration and local equilibrium concentration. The CA simulations for the dendritic microstructures of SCN-ACE alloys during isothermal holding in a mushy zone reproduce the typical dendrite coarsening features as observed in experiments. The effects of holding temperature and alloy composition on the microstructures and dendrite coarsening kinetics are investigated. It is found that the melting of small dendrite arms and interdendritic groove advancement are the two main mechanisms in dendrite coarsening. The mechanism of coalescence by joining arm tips is more likely to take place at a lower temperature or for a lower alloy composition, while the dendrite arm fragmentation mechanism tends to occur at a higher temperature. The coarsening rate constant is found to decrease with increasing holding temperature and alloy composition.
采用二维定量细胞自动机（CA）模型来模拟糊状区中枝晶臂的破碎和枝晶臂的粗化。通过CA模拟很好地呈现了Al-Cu合金在加热过程中枝晶臂破碎的现象，并通过比较局部实际浓度和局部平衡浓度对其进行了详细分析。对SCN-ACE合金在糊状区等温保持期间的枝晶微观结构进行的CA模拟再现了实验中观察到的典型枝晶粗化特征。研究了保温温度和合金成分对微观结构和枝晶粗化动力学的影响。发现小枝晶臂的熔化和枝晶间沟槽的推进是枝晶粗化的两个主要机制。通过连接臂尖进行合并的机制更可能在较低温度或较低合金成分下发生，而枝晶臂破碎机制倾向于在较高温度下发生。发现粗化速率常数随保温温度和合金成分的增加而降低。
