Effect of zinc addition on microstructure and mechanical properties of Mg-7Y-3Sm-0.5Zr alloy
(1. National Engineering Research Center of Light Alloy Net Forming,
Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China)
Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: The effect of zinc addition on the microstructure and mechanical properties of Mg-7Y-3Sm-0.5Zr casting alloy was investigated. Creep test was carried out at 200-300 °C under 50-120 MPa. Within the limits of the creep test conditions used in this study, the creep activation energy of the investigated alloys was in the range of 156-221 kJ/mol. The microstructure evolution during creep was characterized by optical metallography, SEM and TEM. The results show that the creep life of the alloy is increased from 52.2 to 152.8 h at 300 °C under 50 MPa by only 1% addition of Zn, though both the alloys have similar creep behaviors below 250 °C, which suggests that the thermally stable compound and lamellar structure can improve the high temperature creep resistance of the alloy with the addition of Zn.
Key words: Mg-Y-Sm-Zr alloy; zinc; microstructure; mechanical properties; creep behavior