In Vitro Degradation Behavior and Microstructural Evolution of a Novel Biodegradable Zn-Mg-Sr Alloy During Homogenization

Zn alloys have attracted considerable attention owing to their favorable biocompatibility, mechanical strength, and corrosion resistance. Such outstanding biodegradable metallic materials may also have potential practical applications in biomedicine. By means of microstructure characterization, immersion corrosion tests, and electrochemical measurement, this study researched into the effect of homogenization treatment on the microstructure and in vitro degradation behavior of a novel biodegradable Zn-Mg-Sr alloy. The experimental results indicated serious dendritic segregation in the as-cast Zn-Mg-Sr alloy. The metallic phases in the as-cast Zn-Mg-Sr alloy were non-equilibrium MgZn2, Sr-rich SrZn13, and equilibrium Mg2Zn11. By raising the homogenization temperature or lengthening soaking time, the non-equilibrium MgZn2 and SrZn13 gradually dissolved into the Zn matrix, and the dendritic segregation was mostly eliminated. Compared with as-cast Zn-Mg-Sr alloys, homogenized alloys exhibited a slower degradation rate and better pitting corrosion resistance. Based on the experimental results and homogenization kinetic analysis, the optimum homogenizing parameters for the biodegradable Zn-Mg-Sr alloy were 350 °C and 24 h, so the corresponding degradation rate was 0.083 mm/year.