Microstructure and enhanced mechanical properties of Mg-3Sn alloy with Mn addition

Abstract

The effects of Mn content on the microstructure and mechanical properties of the extruded Mg-3Sn-xMn (x = 0, 0.5, 1.5, 2.5) alloys was systematically investigated in this study. More importantly, the relationship between microstructure and mechanical properties of Mg-Sn-Mn alloy was revealed in detail by calculating the various strength contribution value. The microstructure and mechanical properties of the alloys were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and universal testing machine. The results revealed that the average grain size (AGS) decreased from 21.45 μ m to 10.51 μ m and then increased to 13.41 μ m with increasing Mn content. It was observed that the second phases are dispersed in Mg-Sn-Mn alloys, namely the granular Mg _2 Sn phase and the rod-shaped α -Mn. Furthermore, the Mg-3Sn-1.5Mn alloy exhibits the optimal comprehensive mechanical properties with ultimate tensile strength (UTS), yield strength (YS), and elongation to fracture (EL) of 249.5 MPa, 203.3 MPa, and 19.3%, respectively. The YS of Mg-3Sn-1.5Mn alloy was significantly enhanced by 42.5 MPa than that of Mg-3Sn alloy, accompanied by a moderately improved elongation from 15.4% to 19.3%. The higher strength of the Mg-3Sn-1.5Mn alloy was attributed to grain refinement (25.2 ∼ 28.8 MPa) and second phase strengthening (17.097∼17.147 MPa), while the enhanced plasticity of the alloy is due to the weakening of the basal texture, and the higher SF of the prismatic 〈a〉 slip.

Keywords

• Mg-Sn-Mn alloy
• microstructure
• mechanical properties
• strengthening mechanisms