Substantial Improvement in Mechanical Properties and Anti-corrosion Properties of Rolled Zn-Mg-Sr Alloys as an Orthopedic Implant

This study investigates a Zn-Mg alloy, enhanced for biodegradability and biocompatibility, by introducing trace amounts of Sr and subjecting it to hot-rolling. The resulting Zn-Mg-Sr alloy shows a reduced average grain size to 3.35 mu m and a transformed Mg2Zn11 phase from lamellar to finely dispersed particles, while maintaining a uniform SrZn13 phase distribution. The as-rolled alloy exhibits significantly improved mechanical properties, with a tensile strength of 340 MPa and 40% of elongation, attributed to grain-boundary strengthening, reinforcement by second-phase particles, and the presence of intragranular dislocations and nanoscale precipitates. This microstructural refinement enhances the elongation by hindering crack propagation. Corrosion resistance tests reveal the superior performance of the as-rolled alloy, owing to the finely distributed eutectic particles, which mitigated localized corrosion and altered the corrosion morphology from localized to finer corrosion pits. In vitro biocompatibility assessments show over 80% cell viability in C3H10 cultures with 50% Zn-Mg-Sr alloy extract, indicating low cytotoxicity. Furthermore, the alloy exhibits promising bone-promoting properties, highlighting its potential for biomedical applications. Zn-Mg-Sr alloys, processed by rolling, have microstructures with fine grains and particle-shape eutectic structure, which is fully fragmented owing to stress concentration that occurred around ScZn13 phase. Microstructural refinement promotes improvement of mechanical properties and corrosion resistance, meanwhile, inherits good biocompatibility of Zn-Mg-Sr alloys.image (c) 2024 WILEY-VCH GmbH