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 α-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 μm 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.