Effects of Sr addition on microstructures and mechanical properties of Mg-1Zn-1Ca-xSr alloys

Abstract

The Sr-containing magnesium alloys have unique characteristics and demonstrate potentials to broaden the application of magnesium alloys. The microstructures and room temperature tensile properties of the as-cast Mg-1Zn-1Ca-xSr (x = 0.1, 0.5, 1.5, 2.5 weight%) alloys were investigated in this study. The results indicated that the grains of the Sr-containing alloys were gradually refined and the quantity of second phases was obviously increased with increasing the Sr content. In addition, the phase constituents of the alloys were found to be α-Mg, Mg2Ca, Mg6Ca2Zn3 and Mg17Sr2. The tensile results at room temperature showed that the tensile strength and elongation increased for low Sr-content alloys, but didn't change or even decreased a little for high Sr-content alloys. The yield strength changed little with increasing Sr content. The alloy with 0.1% Sr exhibited the best comprehensive properties, with yield strength of 65.69 MPa, tensile strength of 118.23 MPa and elongation of 2.45%. Fracture analysis showed that the fracture mode of the alloys was mainly quasi-cleavage mechanism.