Microstructure evolution and age-hardening response in Mg-Sn-Sm alloys under a wide range of Sm/Sn ratio  

作　　者：Feng Liu Wen-xin Hu Zheng-hua Yang Wei Wang Wei He 

机构地区：[1]State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization,Baotou 014030,Inner Mongolia,China [2]Baotou Research Institute of Rare Earths,Baotou 014030,Inner Mongolia,China

出　　处：《China Foundry》2022年第3期211-217,共7页中国铸造（英文版）

基　　金：the Natural Science Foundation of Inner Mongolia under Grant No.2020MS05014;the Science and Technology Planning of Inner Mongolia under Grant No.2020GG0318.

摘　　要：The microstructure evolution and age-hardening response for different Sm/Sn ratios(0-2.55,in wt.%)of Mg-Sn-Sm alloys were investigated.The second phase formation in as-cast alloys and the Mg_(3)Sm precipitates formed in aged alloys were characterized using XRD,FESEM and HAADF-STEM with EDS techniques.Results indicate that the Sm/Sn ratio has a great influence on the phase constitution,α-Mg grain size and age-hardening response.With the increment of Sm/Sn ratio,Mg_(41)Sm_(5) and thermally stable MgSnSm phases precipitate.When the Sm/Sn ratio is about 1.19,the secondary dendrite arm spacing ofα-Mg grains significantly decreases.Furthermore,the alloy with Sm/Sn ratio up to 2.55 exhibits the highest age-hardening response,the hardness value increases from 52 HB at solution-treated condition to 74 HB at peak-aged condition(ageing at 220 ℃ for a short time of 4 h).This is attributed to the large volume fraction of needle-like Mg_(3)Sm precipitates formed in theα-Mg matrix during ageing treatment,which results in a significant precipitation strengthening effect.

关 键 词：magnesium alloy AS-CAST microstructure evolution AGE-HARDENING PRECIPITATES Sm/Sn ratio 

分 类 号：TG146.22[一般工业技术—材料科学与工程]