Biodegradable Mg–3Zn Alloy/Titanium–Hydroxyapatite Hybrid Composites: Corrosion and Cytotoxicity Evaluation for Orthopedic Implant Applications

This research addresses the demand for biodegradable orthopedic implants by enhancing magnesium-based alloys. Biodegradable magnesium alloy-based hybrid composites, produced through squeeze casting, incorporate titanium (Ti) and hydroxyapatite (HA) particles to improve microstructure, hardness, and compressive strength. The Mg–3Zn/1Ti/1.5HA composite exhibits a 13% increase in hardness and a 15.8% enhancement in compression strength compared to the base MZA alloy. In corrosion assessments at 216 h, MZA/1Ti/1.5HA shows a 21% lower corrosion rate than MZA/1Ti/0.5HA and a 10% lower rate than MZA/1Ti/1HA. The refined grain structure and formation of protective oxide layers resulting from Ti and HA incorporation contribute to enhanced corrosion resistance. Cytotoxicity assessments reveal excellent biocompatibility, with the Mg–3Zn/1Ti/1.5HA composite exceeding an 80% relative growth rate due to the formation of bone-like apatite layer, surpassing MZA/1Ti/0.5HA and MZA/1Ti/1HA. These findings underscore the potential of squeeze-casted magnesium alloy-based hybrid composites, particularly Mg–3Zn/1Ti/1.5HA, as promising orthopedic implant biomaterials.