Rapid cooling effect during solidification on macro-and micro-segregation of as-cast Mg-Gd alloy  

作　　者：Xin Tong Guoqiang You Jingchuan Luo Mahmoud Ebrahimi Guohua Wu 

机构地区：[1]National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai,200240,China [2]College of Materials Science and Engineering,Chongqing University,Chongqing,400045,China [3]National Engineering Research Center for Magnesium Alloys,Chongqing University,Chongqing,400044,China [4]Department of Mechanical Engineering,Faculty of Engineering,University of Maragheh,P.O.Box 55136-533,Maragheh,Iran

出　　处：《Progress in Natural Science:Materials International》2021年第1期68-76,共9页自然科学进展·国际材料（英文版）

基　　金：the Key Project of the National Key Research&Development Program of China(No.2016YFB0301100);the Key Research&Development Project of Guangdong Province(No.2020B010186002);the National Natural Science Foundation of China(No.51775334).

摘　　要：The high performance of as-cast Mg-RE alloys is always related to their high RE additions.However,RE elements can be readily segregated in Mg alloys and the segregation becomes more significant with the increasing RE content.In this research,the effect of cooling rate on the macro-and micro-segregation in the as-cast Mg-8Gd alloy was studied.The Gd content at the bottom of the fabricated ingot with the cooling rate of 4.6~6.9℃/s was~1.7 times of that at the top and coarse eutectics as well as some non-equilibrium phases ofα-Gd,MgGd,Mg2Gd were distributed along the grain boundaries.The formation mechanisms of the specific gravity segregation and grain boundary segregation were also proposed.Upon the application of the water-cooled copper mold with the cooling rate of 27-200℃/s,only fine Mg5Gd and some nanoscale metastableβ1 andβ'phases were found to disperse uniformly in the grain interior,thus the homogeneity of the composition,microstructure,and perfor-mance within the whole ingot was considerably improved.It is expected that these restflts will facilitate the processing design for the fabrication of the highly-homogenized Mg-RE alloy castings.

关 键 词：As-cast Mg–Gd alloy Segregation Rapid cooling SOLIDIFICATION SEDIMENTATION 

分 类 号：TG292[金属学及工艺—铸造]