Mg-Gd合金凝固过程中枝晶生长的相场模拟  

Phase-field Simulation of Dendritic Growth during Solidification of Mg-Gd Alloy

作　　者：王永彪 位明光 贾森森 陈聪 刘新田 WANG Yongbiao;WEI Mingguang;JIA Sensen;CHEN Cong;LIU Xintian(Henan Key Laboratory of Mechanical Equipment Intelligent Manufacturing,Zhengzhou Light Industry University,Zhengzhou 450002,China)

机构地区：[1]郑州轻工业大学河南省机械装备智能制造重点实验室,河南郑州450002

出　　处：《热加工工艺》2020年第9期63-68,72,共7页Hot Working Technology

基　　金：国家自然科学基金-青年科学基金项目(51901208);河南省高等学校重点科研项目(20B430020);郑州轻工业大学博士科研启动基金项目(010013501050043)。

摘　　要：基于Karma定量相场模型对Mg-6Gd(wt%)合金等温凝固过程中单枝晶和多枝晶的生长规律进行了模拟。定量研究了相场参数和溶质偏析对凝固过程中枝晶演化的影响。结果表明,各向异性强度越小,单枝晶尖端的失稳现象越明显,极易生成二次枝晶臂。同时讨论了各向异性强度与枝晶尖端半径和移动速率之间的关系,其结果与微观可解理论吻合较好。空间步长过大会导致枝晶形貌的变异,过小则计算效率低,合理的范围在(0.2~0.8)W0(W0为界面厚度)内。多枝晶生长模拟结果表明,枝晶臂弯曲是由于多枝晶在等温条件下的竞争生长所致。同时,大量溶质在枝晶间富集和分离,抑制枝晶的生长。Based on Karma quantitative phase-field model, the growth rules of single dendrites and multiple-dendrites in Mg-6 Gd(wt%) alloy were simulated under the isothermal solidification. The effects of phase-field parameters and solute segregation on the evolution of dendrites were studied. The results show that the smaller the anisotropic strength is, the more obvious the instability of the single dendrite tip is, and it is easy to generate secondary dendrite arms. At the same time, the relationship between the anisotropic strength and the tip radius and tip velocity of dendrite was discussed. The results are in good agreement with the microscopic solvable theory. Too large spatial step size will cause changes in dendritic morphology,and too small will lead to unacceptable computation costs, and reasonable range should be controlled within the range of(0.2-0.8)W0(W0 is interface thinckness). The simulation results of multi-dendritic growth indicate that dendrite arms bend due to the competitive growth of multiple-dendrites under isothermal condition. Meanwhile, a large number of solutes enrich and segregate between dendrites, inhibiting the growth of dendrites.

关 键 词：相场模拟 枝晶生长 相场参数 溶质偏析 

分 类 号：TG244.3[金属学及工艺—铸造] TG292