High strength magnesium alloy with α-Mg and W-phase processed by hot extrusion

Fine-grained Mg-6Zn-4Y alloy was prepared by an ingot metallurgy process with hot extrusion at 300 C. The microstructure was studied by XRD, OM, SEM and TEM, and the tensile properties were tested at room temperature. The results show that the alloy is composed of alpha-Mg and W-phase. The microstructure of the as-extruded alloy has a bimodal grain size distribution. The fine grains with the mean size of 1.2 mu m are formed by dynamic recrystallization. The coarse grains (about 23% in area fraction) are unrecrystallized regions which are elongated along extrusion direction. The engineering stress-strain curve shows a pronounced yield point. The ultimate tensile strength, yield strength, and elongation are (371 +/- 10) MPa, (350 +/- 5) MPa and (7 +/- 2)%, respectively. The high strengths are attributed to the fine-grained matrix structure enhanced by W-phase particles, nano-scaled precipitates, and strong basal plane texture.