Microstructure and Tensile Properties of Mg-4Zn-2Sn-2Al Alloy

The microstructures and tensile properties of as-cast, solution-treated and aged Mg-4Zn-2Sn-2Al (wt.%) alloy have been investigated. The microstructure of the as-cast alloy consists of α-Mg, Mg2Sn and Mg32(Al,Zn)49 phases. The yield tensile strength and the ultimate tensile strength of the as-cast alloy are 87.7 MPa and 241.3 MPa, respectively, and the elongation reaches to 18.8% showing excellent ductility. After solution treatment, all of the Mg32(Al,Zn)49 phase and the majority of Mg2Sn particles have dissolved into the matrix. During aging process, Mg2Sn phase precipitates from the α-Mg supersaturated solid solution. With the precipitation strengthening of Mg2Sn phase, the yield tensile strength and the ultimate tensile strength of the alloy increase to 112.5 MPa and 280.4 MPa, respectively, while, the elongation decreases to 12%.