LAUSR

This study investigated the microstructure, mechanical properties, corrosion behavior of as-cast Mg–1.8Zn–0.4Zr–1.74Gd– x Y ( x  = 0, 0.25, 0.5, 0.75, 1.0, 1.25 wt%) biodegradable magnesium alloys. Microstructures of the alloys were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the alloys were mainly composed of α-Mg matrix (Mg, Zn) 3 (Gd, Y) phase, Mg 3 Zn 3 (Gd, Y) 2 phase and Mg 12 Zn(Gd, Y) phase. It was found that 0–1.25 wt% Y addition led to significant grain refinement of the alloys from 111.5 to 57.3 μm. Moderate amount of Y resulted in improved strength. However, the strength and elongation decreased when the Y content exceeded 0.5 wt%. With 0.5 wt% of Y, the corrosion rate and corrosion current density were 0.721 ± 0.042 mm y −1 and 4.76 μA cm −2 , respectively, which were lower than the other investigated alloys. Among all the tested samples, Mg–1.8Zn–0.4Zr–1.74Gd–0.5Y alloy has the moderate corrosion rate and mechanical properties, making it promising for the future optimization of the biodegradable Mg–Zn–Zr–Gd–Y alloys.