Effect of Mn content on the microstructure and mechanical properties of Mg-6Li-4Zn-xMn alloys

The as-cast Mg-6Li-4Zn-xMn alloys were prepared and extruded at 280 degrees C with an extrusion ratio of 25:1. The effects of Mn content on the microstructure and mechanical properties of Mg-6Li-4Zn-xMn alloys were investigated in this study. The XRD results show that Mg-6Li-4Zn-xMn alloys consisted of alpha-Mg (hcp) + beta-Li (bcc) duplex structured matrix, MgLi2Zn and Mn phases. The grains of the extruded Mg-6Li-4Zn-xMn alloys were refined by dynamic recrystallization during the extrusion process. The EBSD results show that the extruded alloys had basal textures. The grain size of the extruded alloys decreased while the basal texture was strengthened with the increasing Mn addition. The TEM results show that a large amount of nanoscale Mn precipitates existed in the extruded Mg-6Li-4Zn-1.2Mn alloy, which can effectively inhibit the dynamic recrystallized (DRXed) grains growth during the hot extrusion and is beneficial to the improvement of mechanical properties. Mg-6Li-4Zn-1.2Mn alloy in this research possesses the best mechanical properties with the ultimate tensile strength and yield strength of 321 MPa, 250 MPa, respectively.

Automated summary

In this study, Mg-6Li-4Zn-xMn alloys were prepared and extruded, with the addition of Mn showing significant improvements in mechanical properties. The alloy containing 1.2% Mn exhibited the best mechanical properties, with enhanced strength and resistance to grain growth during extrusion.