Preparing high-strength diluted Zn-Mg alloy as orthopedic implants by refining grain size

Abstract Enhancing the mechanical properties of biodegradable zinc (Zn) alloys is of paramount importance for their biomedical applications. Alloying with magnesium (Mg) represents a promising strategy to augment mechanical performance through appropriate deformation processing, which facilitates grain refinement. Following extrusion, the Zn-0.1 Mg alloy exhibits an average grain size of 8.17 μm, which further decreases to 0.71 μm upon subsequent rolling. This refined microstructure not only bolsters mechanical properties but also enhances corrosion resistance. The increase in strength can be primarily attributed to grain boundary strengthening. In the as-rolled Zn-0.1 Mg alloy with an ultrafine-grained microstructure, grain boundary strengthening emerges as the predominant strengthening mechanism. Moreover, while the as-rolled Zn-0.1 Mg alloy displays pronounced grain boundary corrosion, the as-extruded Zn alloy is more susceptible to pitting corrosion. The improved corrosion resistance observed in ultrafine-grained Zn alloys stems from their higher grain boundary density, which facilitates the formation of a protective corrosion layer. Notably, Zn-0.1 Mg alloys exhibit comparable cytocompatibility, osteogenic potential, and antibacterial properties. Our findings provide an effective approach to enhancing the mechanical properties of diluted Zn-Mg alloys by refining their grain size to the sub-micrometer scale.