Microstructure Evolution and Mechanical Properties of Mg-3Zn-0.5Er-0.5Al Alloy

The microstructure evolution of the Mg-3Zn-0.5Er-0.5Al (mass fraction, %) alloy under the different condition was investigated. The results showed that as-cast Mg-3Zn-0.5Er-0.5Al alloy mainly consisted of primary large irregular Mg4Zn7 phase and needlelike (Mg, Zn, Er, Al) quaternary phase. Mg4Zn7 phase almost dissolved into the matrix after solid solution treatment at 400 oC for 10 h, while the (Mg, Zn, Er, Al) quaternary phase still existed. The solution treated alloy was extruded at 250 °C. The ultimate tensile strength of the as-extruded alloy was approximately 268 MPa and the YTS was approximately 163 MPa companying with an elongation of 28%. The tensile strength of the as-extruded alloy improved obviously, which was mainly attributed to the grain refinement.