High strength and superior ductility of an ultra-fine grained magnesium-manganese alloy

The addition of manganese in magnesium has the positive effects on improving the corrosion resistance, creep behavior and damping capacity, and refining the microstructure of as-extruded Mg-Gd, Mg-Zn, Mg-RE-Zn etc. magnesium alloys. However, magnesium-manganese binary alloys are not considered as structural applications because of their poor ductility and insufficient strength at room temperature which can be attributed to the strong basal texture and coarsened microstructure. In the present work, therefore, microstructure and mechanical properties of Mg-1.0Mn alloy subjected to low temperature extrusion process has been investigated. The results reveal that the alloy shows superior elongation with sustained yield strength at room temperature. The outstanding elongation is explained as the ultra-fined microstructure by reducing the critical resolved shear stress (CRSS) that favors prismatic slip activity to accommodate basal slip. A simultaneous increasing in yield strength and yield anisotropy is as a result of the ultra-fined grains and finer Mn precipitates in the alloy.