A comparative study of the role of Ag in microstructures and mechanical properties of Mg-Gd and Mg-Y alloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:731

Article

Zhang, Yu^1,2,3,4  Rong, Wei^2,3  Wu, Yujuan^2,3  Peng, Liming^2,3  Nie, Jian-Feng⁴  Birbilis, Nick⁴ 

[1] Chongqing Univ, Coll Mat Sci & Engn, Chongqing 400044, Peoples R China

[2] Shanghai Jiao Tong Univ, Natl Engn Res Ctr Light Alloy Net Forming, Shanghai 200240, Peoples R China

[3] Shanghai Jiao Tong Univ, State Key Lab Met Matrix Composite, Shanghai 200240, Peoples R China

[4] Monash Univ, Dept Mat Sci & Engn, Clayton, Vic 3800, Australia

关键词: Mg alloys;    Precipitation;    Mechanical properties;    Fracture;    HAADF-STEM;   

DOI  :  10.1016/j.msea.2018.06.084

来源: Elsevier

【 摘 要 】

Mg-Gd and Mg-Y are two fundamental Mg alloy systems. Four alloys with a equi-concentration of total alloying elements: Mg-2.8Gd-0.1Zr (at%), Mg-2.4Gd-0.4Ag-0.1Zr (at%), Mg-2.8Y-0.1Zr (at%) and Mg-2.4Y-0.4Ag-0.1Zr (at%) were designed. The roles of Ag in the Mg-Gd and Mg-Y alloys were comparatively studied. The Ag addition enhances the age-hardening response of the Mg-2.4Gd-0.4Ag-0.1Zr due to a combined strengthening effect of the prismatic beta' and basal gamma precipitates. In contrast, the Mg-2.4Y-0.4Ag-0.1Zr exhibits a weakened age-hardening response in comparison with the Mg-2.8Y-0.1Zr, which is due to the formation of the basal gamma precipitates at the expense of the prismatic beta' precipitates. The Ag addition also promotes the formation of precipitation free zones (PFZs) along grain boundaries in both Mg-2.4Gd-0.4Ag-0.1Zr and Mg-2.4Y-0.4Ag-0.1Zr. The grain boundary PFZ is supposed to relax stress concentration to some extent during plastic deformation, which is beneficial to ductility. In summary, the Ag addition not only improves the tensile yield strength (YS) and ultimate tensile strength (UTS), but also improves the elongation of the Mg-2.4Gd-0.4Ag-0.1Zr. In comparison, the Ag addition in the Mg-2.4Y-0.4Ag-0.1Zr improves the UTS and elongation but reduces the YS in comparison with the Mg-2.8Y-0.1Zr. The results in this study suggest that Ag is more effective to strengthen Mg-Gd than Mg-Y alloys.

【 授权许可】

Free