The influence of Sc addition on microstructure and tensile mechanical properties of Mg–4.5Sn–5Zn alloys

Abstract

The microstructure and tensile properties of the as-cast and as-rolled Mg–4.5Sn–5Zn alloys by adding various Sc content were investigated. Improvement of the tensile properties in as-cast Sc-containing alloys is attributed to the grain refinement and modification of secondary phase morphology. Three types of precipitates, namely spherical Mg2Sn, rod-like MgZn and Sc-rich phases were dispersed in the matrix of the Sc added Mg–4.5Sn–5Zn alloys after hot rolling deformation. In addition, weakening and deflecting of the basal texture in as-rolled alloys were found and were attributed to Sc addition. Further increasing the Sc addition rate to 0.4 wt.%, however, resulted in the clustering of the Sc-rich phases and was found to reduce the tensile properties of the alloy, especially the elongation. The as-rolled Mg–4.5Sn–5Zn–0.3Sc alloy exhibits an optimum combination of tensile properties. The ultimate tensile strength, yield strength and elongation are 293.0 MPa, 164.2Mpa and 21.5%, respectively, and the elongation is about 68% higher than that of Sc-free alloy. Keywords: Magnesium alloys, Scandium, Microstructure, Mechanical properties