Microstructures and biocorrosion properties of biodegradable Mg–Zn–Y–Ca–xZr alloys

Abstract The influence of Zr microalloying on the microstructures and corrosion resistance of as-cast Mg-3.0Zn-0.6Y-0.3Ca (wt.%) alloy were investigated by means of optical microscopy, X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, immersion testing and electrochemical measurements. The results indicated that Zr induced the formation of a strip-like eutectic phase at the grain boundaries, and discouraged the formation of isolated particles. With the Zr addition, the microstructure was refined and the corrosion resistance was enhanced. The alloy with a Zr content of 0.5 wt.% has an optimal corrosion resistance, which can be attributed to the fine and continuously distributed strip-like I-phase and fine grain structure.