摘要
为探究重稀土对镁合金凝固组织及熔体流动性的影响,分别制备了添加0.3%、0.6%、0.9%、1.2%和1.5%(质量分数)Gd的AZ91D镁合金。采用XRD、SEM-EDS对该合金凝固组织进行物相鉴定和形貌成分分析,双热电偶法对凝固区间及枝晶搭接温度进行测定,螺旋试样模具对熔体流动性进行评估,并采用洛氏硬度计对合金硬度进行测试。结果表明,稀土Gd可明显细化α-Mg晶粒及β-Mg_(17)Al_(12)相的尺寸,当Gd含量为0.9%时,α-Mg平均晶粒尺寸最小,为135.87μm。稀土相Al_(2)Gd主要分布在晶界处且成块状析出。添加适量稀土Gd减小了合金凝固区间,并降低了枝晶搭接温度,使得熔体流动性得到大幅提高。随着Gd含量的增加,合金硬度先提高后降低,当Gd含量为0.9%时,达到最大值75.1 HRB。本研究可为拓展镁合金应用和实现稀土资源综合利用提供理论依据。
In order to investigate the effect of heavy rare earth on the solidification microstructure and melt fluidity of magnesium alloy,AZ91D magnesium alloys with 0.3%,0.6%,0.9%,1.2%and 1.5%(mass fraction)Gd were prepared.The phase identification and morphology and composition analysis of the solidification microstructure of the alloys were carried out by XRD and SEM-EDS.The solidification interval and dendrite coherency temperature were determined via a dual-thermocouple technique.The melt fluidity was evaluated by a spiral sample mold,and the hardness of the alloys was measured by a Rockwell hardness tester.The results show that rare earth Gd can significantly refine both theα-Mg grains andβ-Mg_(17)Al_(12)phase.When the Gd content is 0.9%,the average grain size ofα-Mg is the smallest,which is 135.87μm.The rare earth phase Al_(2)Gd is mainly distributed along the grain boundary and blockily precipitated.The addition of an appropriate amount of rare earth Gd reduces the solidification interval and dendrite coherency temperature of the alloy,which greatly improves the melt fluidity.With the increase of Gd content,the hardness of the alloy increases first and then decreases,reaching a peak of 75.1 HRB at 0.9%Gd.This study can provide a theoretical basis for expanding the application of magnesium alloys and realizing the comprehensive utilization of rare earth resources.
作者
韩静飞
刘香君
郭文涛
张家辉
白庆伟
HAN Jing-fei;LIU Xiang-jun;GUO Wen-tao;ZHANG Jia-hui;BAI Qing-wei(Inner Mongolia Key Laboratory of New Metal Material,College of Materials Science and Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,China;College of Mechanical Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,China;Inner Mongolia Autonomous Region Carbon Neutral Collaborative Innovation Center,Inner Mongolia University of Science and Technology,Baotou 014010,China;Key Laboratory of Green Extraction&Efficient Utilization of Light Rare-Earth Resources,Ministry of Education,College of Rare Earth Industry,Inner Mongolia University of Science and Technology,Baotou 014010,China;China-Ukraine Institute of Welding,Guangdong Academy of Sciences,Guangzhou 510650,China)
出处
《稀有金属与硬质合金》
北大核心
2025年第3期84-92,150,共10页
Rare Metals and Cemented Carbides
基金
内蒙古自治区自然科学基金项目(2024SHZR2341)
内蒙古自治区关键技术攻关计划项目(2021GG0095)
内蒙古自治区一流学科科研专项(YLXKZX-NKD-017,YLXKZX-NKD-041)
内蒙古自治区研究生科研创新项目(S20241109)
内蒙古科技大学基础研究业务费项目(2024QNJS132,2024YXXS016,2024YXXS011)。
关键词
镁合金
AZ91D
重稀土
GD
凝固区间
枝晶搭接点
熔体流动性
硬度
magnesium alloy
AZ91D
heavy rare earth
Gd
solidification interval
dendrite coherency point
melt fluidity
hardness
