冷却速率对Mg-Gd-Y三元镁合金凝固组织影响的相场模拟  

Phase-Field Simulation on the Influence of Cooling Rate on the Solidification Microstructure of Mg-Gd-Y Ternary Magnesium Alloy

作　　者：赵雪婷 尚闪 张天向 张瑞杰 王先飞[4] 李中权[4] 韩志强 Zhao Xueting;Shang Shan;Zhang Tianxiang;Zhang Ruijie;Wang Xianfei;Li Zhongquan;Han Zhiqiang(School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Key Laboratory for Advanced Materials Processing Technology(Ministry of Education),Tsinghua University,Beijing 100084,China;Collaborative Innovation Center of Steel Technology,University of Science and Technology Beijing,Beijing 100083,China;Shanghai Spaceflight Precision Machinery Institute,Shanghai 201600,China)

机构地区：[1]清华大学材料学院,北京100084 [2]清华大学先进成形制造教育部重点实验室,北京100084 [3]北京科技大学钢铁共性技术协同创新中心,北京100083 [4]上海航天精密机械研究所,上海201600

出　　处：《稀有金属材料与工程》2020年第11期3709-3717,共9页Rare Metal Materials and Engineering

基　　金：National Key Research and Development Program of China(2016YFB0701204);National Natural Science Foundation of China(U1737208)。

摘　　要：结合Mg-Gd-Y体系热、动力学模型,首次考虑冷却速率,建立了Mg-Gd-Y三元镁合金的相场模型。应用该模型模拟了GW103(Mg-1.69%Gd-1.32%Y,摩尔分数)合金在不同冷却速率下的凝固组织微观形貌和成分分布。采用重力铸造法制备GW103合金并对其进行试验表征以验证相场模型。结果表明,GW103合金呈不发达枝晶形貌且一次枝晶臂具六次对称性,二次枝晶臂呈突起状且无更高次枝晶臂。在多晶粒相场模拟中,随着冷却速率的增加,GW103微观组织细化,晶粒尺寸减小、一次枝晶臂变细、二次枝晶臂数目减少。较高的冷却速率加剧了Gd和Y在枝晶间的溶质富集现象,令成分分布更不均匀。A phase-field model of ternary Mg-Gd-Y magnesium alloy was developed by coupling with the thermodynamics of Mg-Gd-Y system and considering cooling rate for the first time.It was applied to simulate the solidification microstructure and concentration distribution of GW103(Mg-1.69 mol%Gd-1.32 mol%Y)alloy at different cooling rates both in one-grain and multigrain simulation cases.Then GW103 alloys were prepared by gravity casting method and characterized to verify the model.Results give new understanding that the GW103 alloy exhibits thick six fold primary dendrite,a few protuberance-like secondary arms and even no higher-order arms,instead of developed dendrite.The ascending cooling rate results in refinement of microstructure of GW103,which exhibits smaller grain size,slimmer primary dendrite and less secondary arms in multigrain simulation case.Besides,higher cooling rate aggravates the solute enrichment and inhomogeneous distribution of Gd and Y in interdendritic area.The simulation and the experimental results are matched well.

关 键 词：相场 模拟 镁 微观结构 冷却速率 

分 类 号：TG146.22[一般工业技术—材料科学与工程]