Effect of Gd content on hot-tearing susceptibility of Mg-6Zn-xGd casting alloys  

作　　者：He Qin Guang-yu Yang Xun-wei Zheng Shi-feng Luo Tong Bai Wan-qi Jie 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China [2]Dongfeng Nissan Aeolus Xiangyang Automobile Co.,Ltd.,Xiangyang 441100,Hubei,China

出　　处：《China Foundry》2022年第2期131-139,共9页中国铸造（英文版）

基　　金：supported by the National Key R&D Program of China(Grant No.2018YFB1106800);the National Natural Science Foundation of China(Grant No.51771152).

摘　　要：The hot-tearing susceptibility(HTS)of Mg-6Zn-xGd(x=0.5,1,2,3,4,6)alloys was evaluated using a constrained rod casting(CRC)method.The results show that the HTS curve follows a typical"Λ"shape with the increase of Gd content.The Mg-6Zn-2Gd alloy has the highest while Mg-6Zn-6Gd alloy has the lowest HTS value.The hot-tearing behavior characteristics of Mg-6Zn-xGd alloys were further studied through a multifunctional hot-tearing test device.According to the dendrite contact point inferred from the stress curve,the Clyne-Davies criterion was modified and found to be accurate in predicting the HTS of Mg-6Zn-xGd alloys.Microstructure observation reveals that the grain size and the volume of eutectic liquid are the two key factors affecting HTS of Mg-6Zn-xGd alloys.The large grain with columnar structure can easily promote initiation and propagation of hot-tearing due to the poor feeding and coordinating deformation capability,which have a harmful effect on HTS.A higher volume fraction of eutectic phase can refill the cracking and provide continuous feeding channels by dendrite bridge and thicker liquid film,thus increase the hot-tearing resistance.

关 键 词：Mg-Zn-Gd alloy hot-tearing susceptibility modified Clyne-Davies model microstructure 

分 类 号：TG146.22[一般工业技术—材料科学与工程]