Role of Sr in Microstructure, Hardness and Biodegradable Behavior of Cast Mg-2Zn-2Ca-0.5Mn (ZXM220) Alloy for Potential Implant Application

摘要

Microstructure, hardness and biocorrosion properties of ZXM220-xSr alloys (x = 0, 0.2, 0.4, 0.8 and 1 wt%) were investigated, and the results were compared with each other. Microstructural characterizations were carried out by XRD, optical and scanning electron microscopes. Biocorrosion properties were determined by immersion and electrochemical corrosion tests, performed in a simulated body fluid solution at 37 degrees C. Compared to the Sr-free alloy, Sr-bearing alloys exhibited a smaller grain size and a higher volume fraction of second-phase particles. The hardness of the alloy was also gradually improved by increasing Sr additions. Biocorrosion properties of the alloy significantly improved by 0.2 wt% Sr addition, and these properties deteriorated with higher additions of Sr due to the strong microgalvanic effect of coarse second-phase particles. Therefore, the ZXM220-0.2Sr alloy can be regarded as a promising candidate for a new biodegradable implant material due to the optimum results of mechanical and biocorrosion properties.