Effect of the processing route on the microstructure and mechanical behavior of superlight Mg-9Li-1Zn alloy via friction stir processing

作     者：Mengran Zhou Zhuoran Zeng Chun Cheng Yoshiaki Morisada Qingyu Shi Jian-Yih Wang Hidetoshi Fujii 

作者机构：Joining and Welding Research Institute(JWRI)Osaka UniversityOsakaJapan Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of TribologyTsinghua UniversityBeijingChina Key Laboratory for Advanced Materials Processing Technology Ministry of Education of ChinaTsinghua UniversityBeijing 100084China College of Engineering and Computer ScienceAustralian National UniversityACT 2601Australia Department of Materials Science and EngineeringNational Dong-Hwa UniversityHwa-LianTaiwanChina 

出 版 物：《Journal of Magnesium and Alloys》 (镁合金学报（英文）)

年 卷 期：2022年第10卷第11期

页      面：3064-3081页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：partially supported by the JST-Mirai Program Grant Number JPMJMI19E5 a Grant-in-Aid for Science Research from the Japan Society for the Promotion of Science 

主　　题：Mg-Li-Zn alloy Friction stir processing Microstructure In-situ SEM-DIC Mechanical properties 

摘      要：In this study, the effect of the processing route using a friction stir processing(FSP) method on the microstructure and mechanical behavior of a Mg-9Li-1Zn alloy was systematically investigated. In the FSP method, the odd-numbered(1st and 3rd) process directions and even-numbered(2nd and 4th) passes were alternated to distribute the strain throughout the whole processed zone uniformly. Consequently, the processed zone had a much more uniform microstructure and hardness distribution than the processed zone obtained using the conventional FSP method. Using this method, the grain size of a Mg-9Li-1Zn sheet alloy was refined from ~31 μm to ~0.21 μm with uniformly distributedα and β phases. The processed alloy exhibited a high strength-ductility synergy with an ultimate tensile strength(UTS) of 220.1 MPa and total elongation of 70.0% at a strain rate of 10^(-3)s^(-1), overwhelmingly higher than those of the base metal, 155.6 MPa in UTS and 36.0%in elongation. The in-situ SEM-DIC analysis and TEM observation demonstrated that such an outstanding ductility with moderate strength is caused by grain boundary sliding, the dominant deformation mechanism of the ultra-fine-grained sample after FSP. The processing route with reverse processing direction was proven to be efficient in producing the ultrafine grain size microstructure and improving the mechanical properties of superlight Mg-9Li-1Zn alloy.