Improvement of mechanical properties of hot extruded and age treated Mg–Zn–Mn–Ca alloy through Sn addition

Developing high strength magnesium (Mg) alloys without rare earth elements is a long-term goal in the field of light alloys. Herein, it is indicated that addition with Sn in Mg–Zn–Mn–Ca increased the mechanical properties in hot extruded and age treated condition. The results showed that addition of Sn suppressed the formation of Ca2Mg6Zn3 and a new CaMgSn phase was found in Sn-containing alloys. Addition of Sn promoted recrystallization process for as-extruded alloys. The strength of alloys enhanced gradually with Sn content from 0 wt % to 3 wt % in extrusion state. And the as-extruded Mg–6Zn–1Mn–2Sn-0.5Ca alloy showed a comprehensive mechanical property, with yield strength, ultimate tensile strength and elongation being 299 MPa, 366 MPa and 9.2%, respectively. The main contributor for strengthening was precipitates strengthening. During the aging treatment, Sn addition both refines the precipitates and increases precipitates density. β′ precipitates were still the dominant strengthening phase for aged alloys in this study. The peak aged Mg–6Zn–1Mn–2Sn-0.5Ca alloy exhibited excellent mechanical properties, with yield strength, ultimate tensile strength and elongation being 379 MPa, 407 MPa and 7.5%, respectively.