摘要
研究了稀土Y变质(0%~0.8%,质量分数)对Mg-5Sn-1Si合金显微组织的影响。通过XRD和SEM分析了该合金的组织和相组成。结果表明,受成分过冷的作用,适量Y能有效细化铸态组织。随着Y含量从0.2%增加到0.8%,生长抑制因子GRF值从Mg-5Sn-1Si-0.2Y的16.94增大到Mg-5Sn-1Si-0.8Y的17.96,枝晶臂间距平均尺寸从不含Y的Mg-5Sn-1Si合金的23.7μm减小至Mg-5Sn-1Si-0.8Y合金的12.5μm,减小了约47%。由于Y元素在Mg2Si表面的偏聚,Mg-Y二元相或是Mg-Si-Y三元相将在Mg2Si和α-Mg前沿析出,抑制了共晶Mg2Si的异向生长,使复杂汉字状的Mg2Si转变为棒状组织。当Y含量达到0.8%时,Y元素对Mg2Si变质效果最佳。通过XRD和SEM分析了该合金的相组成,合金由α-Mg基体、Mg2Sn、Mg2Si和少量的Mg24Y5和Mg Si Y组成。使用CASTEP软件包基于第一性原理,计算了三种Mg Si Y晶胞结构的结合能Ecoh,计算结果与Mg2Si结合能的对比,证实了Mg Si Y存在的可能性。
The influence of modification of rare earth Y on the microstructure and phase composition of Mg-5Sn-1Si magnesium alloys were studied.The addition quantity of Y to the alloy is in the range of 0 to 0.8(wt%).The microstructure and phase composition of Mg-5Sn-1Si-xY magnesium alloys were analyzed by XRD and SEM.The results indicate that Y element has refining effect on the as-cast microstructure due to the influence of constitutional under cooling.Increasing Y addition from 0.2%to 0.8%,the value of growth restriction factor(GRF)increases from 16.94 to 17.96 for the alloyed Mg-5Sn-1Si-xY alloy.At the same time,the dendritic arm spacing reduces from 23.7μm for the alloy without Y addition to12.5μm for Mg-5Sn-1Si-0.8Y alloy and decreases by about 47%.Due to the segregation of Y element in the front of solidified Mg2Si,some Mg-Y binary or Mg-Si-Y ternary phases precipitate in the front of the Mg2Si andα-Mg.The precipitated phases restrict the heterotropic growth of the eutectic Mg2Si and furthermore change the complex Chinese characters Mg2Si into rod microstructure.When the Y content is 0.8%,the modification effect of Y on the microstructure of the alloy is excellent.The alloy consists ofα-Mg,Mg2Sn,Mg2Si and a small amount of Mg24Y5 and Mg Si Y.The cohesive energy of three crystal cells of Mg Si Y was calculated by CASTEP(cambridge serial total energy package)based on the first principles and the calculation results were compared with that of Mg2Si,the existence possibility of Mg Si Y was proved.
作者
马健
郭学锋
王英
崔红保
于合帅
MA Jian;GUO Xuefengu;WANG Ying;CUI Hongbao;YU Heshuai(School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;Henan International Joint Research Laboratory for High-Performance Light Metallic Materials and Numerical Simulations, Jiaozuo 454000, China)
出处
《热加工工艺》
北大核心
2019年第12期34-39,共6页
Hot Working Technology
基金
国家自然科学基金项目(51571086,1271073)
河南理工大学自然科学基金项目(B 2010-20)
作者简介
马健(1987-),男,四川德阳人,助理工程师,硕士,研究方向为金属材料与加工工程;E-mail:211606020001@home.hpu.edu.cn;通讯作者:郭学锋(1962-),男,教授,博导,博士,研究方向为金属材料的制备与应用;E-mail:guoxuef@hpu.edu.cn.
