Effects of Li addition on the microstructure and mechanical properties of Mg–3Zn–1Sn–0.4Mn based alloys

•Mg–xLi–3Zn–1Sn–0.4Mn alloys were melted and extruded at 200 °C.•Li addition resulted in the formation of MgLi2Sn intermetallic compound.•Li addition resulted in the development of the random texture.•By Li addition, the ductility was significantly increased.•Sn addition resulted in the improvement of strength.

In this work, Mg–3 wt%Zn–1 wt%Sn–0.4 wt%Mn alloys with different Li addition (5, 8 and 11 wt%) were melted and extruded at 200 °C. Effects of Li addition on microstructure and mechanical properties of as-cast and as-extruded Mg–xLi–3Zn–1Sn–0.4Mn alloys were investigated. Li addition to Mg–3Zn–1Sn–0.4Mn based alloy resulted in the formation of MgLi2Sn intermetallic compound. By Li addition from 5 wt% to 8 and 11 wt%, the ductility was significantly increased from 18.1% to 30.9% and 49.3% at room temperature due to transformation from HCP to BCC crystal structure and formation of a weaker basal texture of the α-Mg phase region. The ultimate tensile strength (UTS) was decreased from 252.0, 201.1 and 148.7 MPa as Li content increased from 5 to 8 and 11 wt%. On the other hand, the tensile strength of Sn containing alloys was remarkably increased compared to the alloys without Sn addition due to the presence of the fine MgLi2Sn intermetallic compounds.