Regulating Mg/Fe interfacial compound formation by in-situ alloying with Gd and Y  

作　　者：Qiang Lang Nan Li Xin Liu Muhammad Shehryar Khan Gang Song Liming Liu 

机构地区：[1]School of Materials Science and Engineering,Dalian University of Technology,Dalian,116000,China [2]Department of Materials Science and Engineering,Massachusetts Institute of Technology,77 Massachusetts Ave,Cambridge,MA 02139,USA

出　　处：《Journal of Magnesium and Alloys》2024年第12期5179-5193,共15页镁合金学报(英文)

基　　金：sponsored by the National Key Research and Development Program of China(2022YFB4600900);the National Natural Science Foundation of China(No.U1960111/52375309);the Liaoning Province Applied Basic Research Program Project(2023JH2/101300157)。

摘　　要：This study revealed that the presence of Cr and Ni in stainless steel is one of the leading causes for the weakening of the Mg/Fe interface when using a traditional Mg-Zn-Al(i.e.,AZ61)filler wire.By using a novel Mg-Gd-Y-Zr filler wire without Al,the interfacial structure between Mg/Fe was optimized,and the joint integrity was significantly improved.Using advanced multiscale characterization tools,the coherent matching mechanism of rare earth elements in regulating Mg/Fe interfacial compounds was clarified.The results showed that Gd and Y exhibited lower diffusion activation energy and faster diffusion rates in Fe compared to Al resulting in IMCs with more stiffness and mechanical integrity than Al-Mg compounds that are generated at the Mg/Fe interface when using the AZ61 filler wire.High-resolution TEM results revealed that the lattice distortion caused by the diffusion of metal elements changes the original semi-coherent matching interfaces of(0001)_(HCP-Mg)and(012)_(BCC-Mg24(Y,Gd)5),as well as lattice planes of(012)_(BCC-Mg24(Y,Gd)5)and(5723)_(HCP-Fe17(Y,Gd)2)into a coherent matching interface,which is known to improve mechanical strength.Although lattice planes of(5723)_(HCP-Fe17(Y,Gd)2)and(111)_(BCC-Fe)were found to be incoherent interfaces,it was found that Gd,Y,and Zr with larger atomic radii compared to Al diffused into the bulk Fe to form a wide range of(Fe,Gd,Y,Zr,Cr,Ni,Mn)interstitial solid solutions,which helped strengthen the integrity of the joint.The results showed that the load bearing capacity of the AZ31B/Mg-RE/316 L joint was about 290 N/mm,which is 2.5 times that of the AZ31B/AZ61/316 L joints,which was measured at 115 N/mm.

关 键 词：Laser-GTAW hybrid welding Dissimilar materials Magnesium alloy Stainless steel Rare earth Coherent interface 

分 类 号：TG457.1[金属学及工艺—焊接]