Improving the strength and ductility of magnesium alloys by Sc alloying: An experimental and first-principles study

Mg–Sc alloys have great application potential due to the positive effect of Sc on improving corrosion resistance and mechanical properties. In this work, the effects of Sc content on the strength and ductility of Mg-xSc (x=0, 1, 2, 3 at.%) alloys were investigated by experiments and first-principles calculations. The results indicate that, with the increase of Sc content, the hardness, strength, and ductility of the alloys increase significantly. The improvement of strength is attributed to the solid solution strengthening and grain size refinement effect. The addition of Sc reduces the prismatic unstable stacking fault energy of the alloys, thereby promoting the activation of stacking faults and dislocations, resulting in the significant improvement of ductility. The mechanism of the enhanced ductility of Mg-xSc solid solution alloys is revealed, which provides guidance for designing high-performance Mg alloys. •The addition of Sc improves the strength and ductility of Mg–Sc binary alloys.•More stacking faults and dislocations occur with the addition of Sc.•The addition of Sc reduces the prismatic unstable stacking fault energy of Mg alloys.