Insights of Microstructural Features and Their Effect on Degradation and the In Vitro Bioactivity Response of as-Cast Mg-Sn Alloys for Orthopedic Implant Applications

The present work focuses on a deep understanding of microstructural evolution and phase formation in a binary Mg-Sn alloy system. Mg-xSn (x = 1, 5, 10 wt.%) alloys were cast using a squeeze casting technique. Phase identification and microstructural analysis were done using XRD (X-ray Diffraction) and FESEM with EDS (Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy), respectively. The mechanical behavior of the alloys under study was evaluated by conducting a compression test. The corrosion behavior of all the alloys were intricately studied using electrochemical corrosion tests and an immersion test in the simulated body fluid (SBF) environment for different immersion periods. The bioactivity response of Mg-Sn alloys systems under this study was investigated by immersing the samples in SBF for 14 days. From the analysis of the results, it was understood that the amount of Sn addition has a large influence on the metallurgical, corrosion, and bioactivity properties. Interesting facts about the intermetallic phase formation and segregation of Sn were observed when the wt.% of Sn was varied in the alloy and the evolution of the microstructure was described clearly. Mechanical properties of Mg-Sn alloys were improved, as the Sn content increased up to 5 wt.% and declined in the case of a 10 wt.% Sn addition. A similar trend was observed even in the case of corrosion resistance and bioactivity properties. Among the alloy compositions studied, Mg with a 5 wt.% addition has proved to be a promising candidate material for orthopedic implant applications with an acceptable elastic modulus, higher corrosion resistance, and an excellent bioactive response.