Effect of Y addition on microstructure and mechanical properties of extruded Mg–Mn alloys

Two homogenized as-cast magnesium (Mg)–1 wt% manganese (Mn) alloys containing 1·0 and 4·0 wt% alloying yttrium (Y) were processed at an extrusion ratio of 17:1 at 400°C using a ram speed of 0·3 mm/s. The effect of yttrium additions on the microstructure and mechanical properties of the extruded alloy was analyzed and compared. The average grain size of the extruded Mg–1Mn–4Y (MW14) alloy was much smaller than that of the extruded Mg–1Mn–1Y (MW11) alloy. In addition, the tensile strength of the MW14 alloy was higher than that of the MW11 alloy at the investigated temperature ranging form RT to 200°C, although the former exhibited a lower elongation to failure. The fracture surface of the MW14 alloy exhibited the cleavage fracture mode. Conversely, a dimple was observed in the MW11 alloy which the significant differences in performance between the two alloys are attributed to their Y contents.