Effect of Zn on mechanical and corrosion properties of Mg-Sc-Zn alloys

The effect of different Zn concentrations (0 wt.%, 1 wt.%, 3 wt.%, and 6 wt.%) on the microstructure, corrosion property, and mechanical property of Mg-0.3Sc-xZn (x = 0 wt.%, 1 wt.%, 3 wt.%, and 6 wt.%) alloys was investigated. Here, MSZ1 alloy exhibits the highest corrosion resistance (0.194 mm/y) and appropriate mechanical properties with an ultimate tensile strength of 228 MPa and elongation of 19%. The superior corrosion resistance of Mg-0.3Sc-1Zn alloys is attributed to the homogeneous volta-potential distribution and the dense corrosion product film. With the increase in zinc content, the strength and plasticity of Mg-0.3Sc-xZn alloys (x = 0 wt.%, 1 wt.%, 3 wt.%, 6 wt.%) improved to some extent. The precipitated ScZn phase plays the role of the second phase strengthening, which enables MSZ6 to obtain the maximum tensile strength. However, the ScZn phase with low volta potential intensifies the galvanic corrosion, resulting in the decline of the corrosion performance.