Microstructure and mechanical properties of as-cast and solid solution treated Mg-8Li-xAl-yZn alloys
(1. National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
2. State Key Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: The effects of Al/Zn ratio (mass ratio) on microstructure and mechanical properties of the Mg-8Li alloy were investigated. The results indicate that in the as-cast Mg-8Li-xAl-yZn (x+y=5) alloys (LAZ alloys), when the Al/Zn ratio is 1:4 and 2:3, the secondary phases are mainly AlLi and MgLiZn phases; when the Al/Zn ratio is 3:2 and 4:1, the secondary phases are mainly AlLi and MgLi2Al phases. The decomposition temperature of MgLiZn phase is about 300 °C and the decomposition temperatures of AlLi phase and MgLi2Al phase are higher (~350 °C). Solid solution strengthening is the main factor for the improvement of strength of Mg-8Li-xAl-yZn alloys. The Mg-8Li-3Al-2Zn alloy after solution treatment at 350 °C for 4 h has the best comprehensive mechanical properties (yield strength of 272.5 MPa, ultimate tensile strength of 315.0 MPa and elongation of 3.4%) among the studied as-cast and solid solution treated Mg-8Li-xAl-yZn alloys.
Key words: Mg-Li alloy; Al/Zn ratio; microstructure; mechanical properties