Jiangsu Key Laboratory for Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing, 211189, China.
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Sci Rep. 2017 Dec 19;7(1):17809. doi: 10.1038/s41598-017-17857-2.
The microstructural evolution of dendrite coarsening during isothermal holding is simulated using a quantitative cellular automaton (CA) model involving the mechanisms of both solidification and melting. The present model encompasses the essential aspects of thermodynamics and kinetics, particularly the evolution/influence of composition, temperature, and curvature, leading to valid simulations of simultaneous solidification and melting. Model validation is performed through a comparison of the CA simulations with analytical predictions for a liquid pool migrating in the mushy zone of a SCN-0.3 wt.% ACE alloy due to temperature gradient zone melting. The model is applied to simulate the microstructural evolution of columnar dendrites of a SCN-2.0 wt.% ACE alloy during isothermal holding in a mushy zone. The simulation results are compared with those of a previous CA model that does not include the melting mechanism under otherwise identical conditions. The role of melting for dendrite coarsening is quantified, showing how the melting influences the coarsening process. The present model effectively reproduces the typical dendrite coarsening features as observed in experiments reported in the literature. The simulations reveal how local solidification and melting stimulate each other through the complicated interactions between phase transformation, interface shape variation, and solute diffusion.
采用包含凝固和熔化机制的定量元胞自动机（CA）模型模拟了等温保持过程中枝晶粗化的微观结构演变。本模型包含了热力学和动力学的基本方面，特别是成分、温度和曲率的演变/影响，从而可以有效地模拟同时凝固和熔化。通过将 CA 模拟与由于温度梯度区熔在 SCN-0.3wt.%ACE 合金糊状区迁移的液池的分析预测进行比较，对模型进行了验证。该模型应用于模拟 SCN-2.0wt.%ACE 合金在糊状区等温保持期间的柱状晶枝晶的微观结构演变。将模拟结果与在其他条件相同的情况下不包括熔化机制的先前 CA 模型的结果进行了比较。定量研究了熔化对枝晶粗化的作用，表明了熔化如何影响粗化过程。本模型有效地再现了文献中报道的实验中观察到的典型枝晶粗化特征。模拟揭示了局部凝固和熔化如何通过相变、界面形状变化和溶质扩散之间的复杂相互作用相互刺激。
