Microstructure, Mechanical, and Electrochemical Corrosion Performance of Ti/HA (Hydroxyapatite) Particles Reinforced Mg-3Zn Squeeze Casted Composites

This research presents a novel approach to overcome the stress shielding effect and non-degradability commonly observed in metallic implants, which often require revision surgery. The study introduces a hybrid metal/ceramic (Ti/HA) reinforcement within the Mg-3Zn binary alloy matrix fabricated using the squeeze casting technique. The alloy matrix incorporates 1 wt% Ti and varying weight percentages (0.5, 1, and 1.5 wt%) of hydroxyapatite (HA). Microstructure analysis revealed significant grain refinement in the alloy upon adding the hybrid reinforcement. Phase analysis using XRD confirmed the presence of Mg-Zn intermetallic phases and corresponding reinforcement phases. Vickers microhardness testing demonstrated a 14.4% (89 HV) increase in hardness for the hybrid composite with 1Ti/1.5HA compared to the unreinforced alloy and other composites. Compressive testing revealed enhanced mechanical properties in the hybrid composites. The 1Ti/1.5 HA hybrid composite displayed a 12% (121 MPa) increase in compressive yield strength (CYS) compared to the alloy, while the 1Ti/1HA hybrid composite exhibited an impressive 22.5% (217 MPa) increment in compressive strength. Corrosion performance evaluation in a phosphate-buffered saline (PBS) environment indicated that the 1Ti/1.5 HA hybrid composites demonstrated comparable corrosion performance to the unreinforced alloy, with a corrosion density of 4.53 × 10−5μA/cm2and a linear polarization resistance of 893 ohms. Based on the findings, the Mg-3Zn alloy with 1Ti/1.5 HA hybrid reinforcement emerges as a promising material for load-bearing biodegradable implants.