Effect of manganese on microstructure and properties of Mg-2Gd magnesium alloy

Effect of various Mn content (0, 0.5, 1.3, 1.5 2.0 wt%) on microstructure and mechanical properties were systematically investigated. The 0.5 wt% Mn addition results in complete recrystallization of as-extruded Mg-2Gd alloy, thus providing the best ductility comparable to other alloys. In the as-extruded Mg-2Gd-0.5Mn alloy, the majority of grains have a soft orientation, which is advantageous for starting basal slip and reducing the yield asymmetry. When the content of Mn exceeds 1.3 wt%, Mn takes effect in refining the grain size of as-extruded alloys but increases the proportion of unrecrystallization microstructure. With the addition of Mn, the strength of as-extruded alloys increases gradually while the ductility deteriorates. The main reasons for the strength increase are attributed to the combination of fine-grained strengthening, precipitation strengthening and texture strengthening. Besides, the addition of Mn enhances the corrosion resistance of as-extruded Mg–Gd alloys system because Mn removes harmful impurities.