Abstract:Mg-6Al-2Nd-2Ca alloy and Mg-6Al-2Nd-2Ca-1.2Zn alloy were prepared by the gravity casting method in a permanent mould. The as-cast alloys were homogenized, hot extruded and thereafter tested and analyzed by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and tensile test. Effect of Zn addition on the microstructure and mechanical properties of Mg-6Al-2Nd-2Ca alloy were analyzed. The experimental results show that the addition of Zn could refine grains, which mainly exist in the α-Mg matrix, reduce the solid solubility of Al in the α-Mg matrix and generate more Al-Nd phases. After homogenization treatment, the microstructure of the two alloys were more uniform, and the amount of precipitated phase was reduced compared with that of the as-cast alloys. After hot extrusion, the hard and brittle phases in the two alloys were crushed, the grains was refined, and the mechanical properties was obviously improved. The tensile strength, yield strength and elongation of the Mg-6Al-2Nd-2Ca-1.2Zn were 294.0 MPa, 197.1 MPa and 11.6%, respectively, which were attributed to the combination of refinement strengthening and second phase strengthening.