(1. 南昌航空大学 轻合金加工科学与技术国防重点学科实验室，南昌 330063；
2. School of Engineering, The Ohio State University, Columbus, OH 43210, USA)
摘 要: 基于KKS相场模型，针对hcp晶系镁合金，建立了一个耦合溶质场、流场、取向场和温度场的多枝晶生长相场模型。为了描述具有不同晶体学取向的多枝晶生长并减少计算量，该模型采用Kobayashi等提出的通过扩散奇异性来保持晶粒内部取向一致的方法，引入取向场θ来对不同晶粒的结晶取向进行描述，实现了单相场控制不同取向多个枝晶的生长。为进一步提高计算效率，在模型求解中使用了二重网格技术。以AZ91D合金为例，对纯扩散下和强迫对流作用下不同取向多枝晶的生长行为进行了模拟，并与实验结果进行对比，模拟结果与实验结果十分吻合。
关键字: 镁合金；相场法；多枝晶；取向场；计算机模拟
（1. National Defence Key Discipline Laboratory of Light Alloy Processing Science and Technology Institute,
Nanchang Hangkong University, Nanchang 330063, China;
2. School of Engineering, The Ohio State University, Columbus, OH 43210, USA）
Abstract:Based on the KKS model which couples concentration field, flow field, orientation field and temperature field, the phase-field model for magnesium alloys with hcp structure was developed. In order to simulate the growth of multiple grains with different preferred growth orientation and reduce calculation amount, a orientation field which keeps the same of orientation in the interior of the grain using the strangeness of diffusion is added to describe the crystallographic orientation, which implements the control of multiple grains with different preferred growth orientation using one phase field controlling equation. The double mesh technique is used to solve the model in order to improve the computing efficiency ulteriorly. Taking AZ91D alloy for example, the dendritic growth of multiple grains with different preferred growth orientation during solidification without and with flow are simulated, the microstructure simulation results are compared with the experimental results, and they are in good agreement in dendritic morphology.
Key words: magnesium alloy; phase-field method; multiple grains; orientation field; computer simulation
