The microstructure and corrosion resistance of Mg–Zn-0.5Ag-xCa (x=0, 0.5, 1.0, 1.5 wt%) alloys in Hank's solution

Abstract

Due to the excellent biocompatibility of Zn, Ag, and Ca, these elements were chosen for the development of a Mg–Zn–Ag–Ca alloy system for biomedical applications. This study studied the effect of Ca on the microstructure and corrosion behavior of as-cast Mg–Zn-0.5Ag-xCa alloy. The composition and microstructure of the alloys were analyzed using metallographic microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The alloys were immersed in Hank's solution for weight loss experiments to analyze the corrosion rate and micro-corrosion morphology of alloys with different Ca contents. It was observed that with the increase of Ca content, grain refinement and the amount of the second phase increased. Corrosion tests in Hank's solution demonstrated that a minor addition of Ca could reduce the corrosion rate, but the rate increased sharply once the Ca content exceeded 1.0 wt%. Considering corrosion performance, the optimal range of Ca concentration was determined to be 1.0 wt% to 1.5 wt%.