Precipitate characteristics and their effects on the mechanical properties of as-extruded Mg-Gd-Li-Y-Zn alloy  

作　　者：Zijian Yu Xi Xu Adil Mansoor Baotian Du Kang Shi Ke Liu Shubo Li Wenbo Du 

机构地区：[1]College of Materials Science and Engineering,Beijing University of Technology,Beijing,100124,PR China

出　　处：《Journal of Materials Science & Technology》2021年第29期21-35,共15页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(No.51801048);the Beijing Municipal Natural Science Foundation(No.2202004)。

摘　　要：In this work,a high-performance Mg-8.4 Gd-4.4 Li-3.5 Y-1.4 Zn(wt%)alloy was successfully prepared by low-temperature hot extrusion.The studied alloy has a TYS of 295±1 MPa and an EL of 2.5%±0.2%at room temperature,159±8 MPa and 15.9%±1.4%at 150℃,and 143±4 MPa and 19.8%±1.8%at200℃.The high performance at tempe ratures up to 200°is attributed to the dispersion strengthening of three Mg3 RE phase variants,the solid solution strengthening of alloying elements and the bimodal structure consisting of fine DRXed grains with random texture and coarse un-DRXed grains with basal texture.A novel island shapedβ_(1 R)phase(FCC,a=0.78 nm)with a size of 30 nm-100 nm is observed in the studied alloy.Theβ_(1 R)phase precipitates on the{1100}_(α)prismatic planes.The strain-induced,dislocationassisted dynamic precipitation during low-temperature hot extrusion is responsible for the formation of theβ_(1 R)phase.The growth of theβ_(1 R)phase is owing to the aid of the formation and transformation of zig-zag structures.The basal slip of dislocations is the dominate deformation mechanism of the studied alloy in the early stage of tensile deformation at room temperature,while non-basal slip of and dislocations at 200℃.Due to the strong interaction betweenβ_(1 R)precipitates and dislocations,the densely distributedβ_(1 R)precipitates significantly improve the mechanical properties via the Orowan strengthening both at room temperature and elevated temperatures.

关 键 词：Mg-RE-Li alloy Rare earth Mechanical properties Metastable phase Hot extrusion 

分 类 号：TG379[金属学及工艺—金属压力加工]