Abstract:The Zn-Mg alloys with Mg additions of 35%, 40% and 45%(mass fraction) were prepared by conventional casting method, with the aim to develop new biodegradable materials. The effects of cooling rate and composition on the microstructures, hardness and corrosion resistance were studied by XRD, SEM, microhardness and corrosion testing techniques. The corrosion behaviors of experimental alloys in simulated body fluids were analyzed. The results show that the amount of the petal-like MgZn₂ phase decreases, as well as the hardness of the alloys, but that of the polygonal MgZn₂ phase increases with the increase of Mg content when the cooling rate is constant. When the alloy composition is constant, the MgZn₂ phase changes easily from petal-like to polygon, and the hardness decreases with the decrease of the cooling rate.

Key words: Zn-Mg alloys; microstructure; corrosion behavior