Composition optimization of high-strength Mg-Gd-Y-Zr alloys based on the structural unit of Mg-Gd solid solution

Rui Jiang¹，Shengnan Qian¹，Chuang Dong^1,2，Ying Qin¹，Yujuan Wu³，Jianxin Zou³，Xiaoqin Zeng³

1. Key Laboratory of Materials Modification (Ministry of Education), School of Material Science and Engineering, Dalian University of Technology2. School of Materials Science and Engineering, Dalian Jiaotong University3. National Engeering Research Center of Light Alloys Net Forming, School of Material Science and Engineering, Shanghai Jiao Tong University

摘 要：Mg-Gd-Y-Zr alloys with high strength fall within narrow composition range.The present paper explains their composition rule by establishing the cluster-plus-glue-atom unit of Gd-containing Mg solid solution with the aid of Mg matrix and Mg₅ Gd precipitate phase.First,based on the structural homologue between Gd-containing Mg solid solution and Mg₅ Gd precipitate phase and in combination with our previously established method for calculating the glue atoms,[Gd-Mg₁₂]Mg₅ is obtained as the chemical unit of Gd-containing Mg solid solution.Then,seven compositions are designed using different combinations of this unit and that of pure Mg [Mg-Mg₁₂Mg₃.After a systematic experimental investigation on the microstructure and mechanical property evolutions as a function of the unit proportions,it is revealed that the Mg-10.1 Gd-3.3 Y-0.9 Zr alloy,being issued from equi-proportion mixing of the two units,shows the strongest tendency of precipitation and reaches the highest strength of 374 MPa after aging.The composition and strength of this alloy are quite close to GW103 K which is well recognized for its general mechanical performance in Mg-Gd-Y-Zr system.

关键词：