Biodegradable Zn-3Mg-0.7Mg₂Si composite fabricated by high-pressure solidification for bone implant applications

Zinc (Zn)-based alloys have been considered potential biodegradable materials for medical applications due to their good biodegradability and biocompatibility. However, the insufficient mechanical properties of pure Zn do not meet the requirements of biodegradable implants. In this study, we have developed a biodegradable Zn-3Mg-0.7Mg₂Si composite fabricated by high-pressure solidification. Microstructural characterization revealed that the high-pressure solidified (HPS) composite exhibited uniformly distributed fine MgZn₂ granules in an α-Zn matrix. Comprehensive tests indicated that the HPS composite exhibited exceptionally high compression properties including a compressive yield strength of 406.2 MPa, an ultimate compressive strength of 1181.2 MPa, and plastic deformation up to 60% strain without cracking or fracturing. Potentiodynamic polarization tests revealed that the HPS composite showed a corrosion potential of -0.930 V, a corrosion current density of 3.5 μA/cm², and a corrosion rate of 46.2 μm/y. Immersion tests revealed that the degradation rate of the HPS composite after immersion in Hanks' solution for 1 month and 3 months was 42.8 μm/y and 37.8 μm/y, respectively. Furthermore, an extract of the HPS composite exhibited good cytocompatibility compared with as-cast (AC) pure Zn and an AC composite at a concentration of ≤25%. These results suggest that the HPS Zn-3Mg-0.7Mg₂Si composite can be anticipated as a promising biodegradable material for orthopedic applications.