Microstructure, mechanical property, in vitro biodegradation behavior and biocompatibility of as-extruded Mg-2Zn-0.2Zr-xNd (x=0.2, 0.6, 1.0) alloys

The microstructure, mechanical property and in vitro degradation behavior of as-extruded Mg-2Zn-0.2Zr-xNd (ZK-xNd, x = 0.2, 0.6, 1.0, wt%) alloys were investigated. The 1.0% Nd addition in Mg-2Zn-0.2Zr (ZK) alloy refines grains, promotes the formation of the MgZn2Nd phase and weakens the basal texture. As-extruded ZK0.2Nd alloy exhibits a low degradation rate (Dw = 1.13 & PLUSMN; 0.15 mm & BULL;y  1). In the early immersion stage, an intergranular degradation occurs because of few dislocations at grain boundaries. With the immersion proceeding a homogeneous degradation occurs and compact rich Ca-P by-products form. All tested ZK-Nd alloys exhibit no cytotoxicity on HUVEC cells. The tensile strength and ductility, however, have no obvious change. It is mainly attributed to less solid solution strengthening, precipitation strengthening and the premature failure caused by incoherent interfaces between the hard MgZn2Nd phase and & alpha;-Mg matrix.