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

摘要

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 M g-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 293.0MPa,164.2Mpa and 21.5%,respectively,and the elongation is about 68%higher than that of Sc-free alloy.