Microstructural, Mechanical, and Electrochemical Characterization of Calcium-Modified Mg-Zn Biodegradable Alloys

Magnesium has been of interest to researchers as a potential biodegradable alternative to metal orthopedic implants due to its biocompatibility and mechanical properties that are similar to those of bone. However, magnesium implants corrode more quickly than would be beneficial. This study focused on the influence of calcium modification on the microstructure and mechanical and electrochemical degradation (in simulated body fluids at 25 °C and 40 °C) of selected Mg-Zn alloys. Four alloys, Mg1Zn, Mg2Zn, Mg1Ca1Zn, and Mg1Ca2Zn, were fabricated by levitation induction melting under an argon atmosphere. Microstructural characterization was performed using optical microscopy and SEM/EDS analysis, mechanical behavior was evaluated by microhardness testing and Gaussian mixture modeling, and corrosion performance was assessed in Ringer's lactate solution. The results indicated that calcium addition modified the microstructural morphology. Moderate Ca addition modified the distribution of secondary phases and altered the local mechanical response of the Mg matrix. Among the investigated compositions, Mg1Ca1Zn exhibited the best balance between the microstructural characteristics, mechanical properties, and corrosion resistance. These results provide useful criteria for the further development of Mg-based alloys for temporary bone fixation applications, particularly where compressive loading is predominant.