Effects of stress loading mode on microstructures and properties of Mg-9Gd-2Nd-0.5Zr alloy treated by creep aging

作     者：Simin Shen Yongpeng Zhuang Ming Li Hongxia Wang Lifei Wang Weili Cheng Hang Li Hua Hou Kwangseon Shin 

作者机构：College of Materials Science and EngineeringShanxi Key Laboratory of Advanced Magnesium based MaterialsTaiyuan University of TechnologyTaiyuan 030024China Southwest Technology and Engineering Research InstituteChongqingP.R.China School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of Materials Science and EngineeringNorth University of ChinaTaiyuan 030051China Magnesium Technology Innovation CenterSchool of Materials Science and EngineeringSeoul National UniversityGwanak-roGwanak-guSeoul 08826Korea 

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

年 卷 期：2023年第11卷第11期

页      面：4263-4273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：supported by Natural Science Foundation of Shanxi province (20210302123135,20210302123163) Science and Technology Major Project of Shanxi province (20191102008) Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi province (202104021301022) The Ministry of Science and Higher Education of the Russian Federation for financial support under the Megagrant (No.075-15-2022-1133) the National Research Foundation (NRF) grant funded by the Ministry of Science and ICT (2015R1A2A1A01006795) of Korea through the Research Institute of Advanced Materials The central government guided local science and technology development projects (YDZJSX2021A010) China Postdoctoral Science Foundation (2022M710541) the projects of International Cooperation in Shanxi (201803D421086) Research Project Supported by Shanxi Scholarship Council of China (2022- 038) 

主　　题：Mg-9Gd-2Nd-0.5Zr alloy Precipitated phase Stress orientation effect PFZ Mechanical properties 

摘      要：Creep aging forming(CAF) is a potential process used to manufacture large integral components of magnesium(Mg) alloys. The selected stress plays a crucial role in creep aging processes but the mechanism by which stress loading method affects creep aging of Mg alloys is still unclear. In this paper, the microstructural evolution of precipitated phases and precipitation-free zones(PFZ) at grain boundaries with different stress loading modes(unstressed, unidirectional tensile stress, and cyclic stress) at 250 ℃ were investigated along with changes in mechanical properties. The results showed that the addition of stress during aging effectively promoted the precipitation of precipitated phases, while unaffecting grain size. Unidirectional tensile stress caused directional growth of β phase([1010]), as well as rotation of weave towards the basal plane texture, resulting in namely stress orientation effect. Solute atoms diffused in the direction of tensile stress while vacancies moved perpendicular to the direction of tensile stress, resulting in PFZ at grain boundaries(157.06 nm). By contrast, cyclic stresses led to the growth of β phase in three directions([1010], [1100] and [0110]). The solute atoms and vacancies were uniformly distributed in the Mg matrix instead of directional diffusion, effectively reducing the width of PFZ(112.39 nm) at the grain boundary. These features significantly improved the mechanical properties of alloy specimens after cyclic stress creep aging when compared to unidirectional stress creep aging, with yield strength(YS), ultimate tensile strength(UTS), and elongation(EL) enhanced from 171.6 MPa, 305.5 MPa, and 4.4%to 174.8 MPa, 326.3 MPa, and 6.9%, respectively.