Effect of Ag Addition on Microstructure, Mechanical and Corrosion Properties of Mg-Nd-Zn-Zr Alloy for Orthopedic Application

The as-extruded Mg-3Nd-0.2Zn-0.4Zr-xAg (x=0, 0.2, 0.5, 1 wt%) alloys were prepared for biomedical applications. Scanning electron microscope, electron backscattered diffraction, X-ray diffraction, tensile test machine, electrochemical workstation, and immersion experiments were used to study microstructures, mechanical properties, and corrosion behavior of the as-extruded alloys. The results indicate that the microstructures of all the as-extruded alloys are composed of coarse undynamic recrystallized grains, fine equiaxed recrystallized grains, and precipitated phases. Ag element plays a positive role in promoting dynamic recrystallization and grain refinement. And during the extrusion, all the four alloys generate a < 10 (1) over bar0 >//ED fiber texture. With the increase of Ag element, the volume fraction of Mg12Nd phase increases and then decreases slightly. By increasing Ag addition, both yield strength and ultimate tensile strength of the as-extruded alloys reduce first and then improve, and the elongation improves gradually from 9.4 to 12.7%. More importantly, the addition of Ag accelerates corrosion of the as-extruded alloys in simulated body fluid, and all the as-extruded alloys show uniform corrosion mode.