Compression yield behavior and corresponding microstructure characterization of Mg-1.5Sn (at.%) alloys

The compression yield behavior and corresponding microstructure characterization of as-cast and as-extruded Mg-1.5Sn (at.%) alloys are investigated by uniaxial compression and electron backscatter diffraction (EBSD). The as-cast and as-extruded Mg-1.5Sn alloys are uniaxially compressed at room temperature with a strain rate of 1 × 10−3 s−1. It shows that the extrusion obviously improves the compressive strength of Mg-1.5Sn alloys with an obvious yield plateau. A new-found micro-structure evolution and compression yield behavior of as-cast and as-extruded Mg-1.5Sn alloys are discussed in detail. The microstructure of as-extruded Mg-1.5Sn alloy is composed of refined dynamic recrystallization grains (DRXed grains) and un-dynamic recrystallization grains (unDRXed grains). The DRXed grains are beneficial to the dislocation slip and grains rotation. Meanwhile, the result shows that the {11–20} twins grow at about 45° along the long axis of unDRXed grains regularly, which probably alleviates the accumulation of dislocations. The compression deformation mechanism is different in various strain stages, resulting in an obvious yield plateau. However, the compression yield plateau is not observed in the as-cast Mg-1.5Sn alloy with a noticeable compressive elastic and a lower strength due to its coarse and relatively uniform grains. The differences on compression behavior between as-cast and as-extruded Mg-1.5Sn alloys are discussed clearly, which can provide a theoretical basis and reference for the further development of high-strength and high-elastic Mg alloys.