Development of biodegradable Zn–Li–Mg alloy with superior mechanical and corrosion properties fabricated by laser powder bed fusion technology

Zn alloys exhibit appropriate degradation rates and acceptable biocompatibility for load-bearing bone implants and have attracted great attention in recent years. However, biomedical applications of pure zinc (Zn) are restricted by its insufficient mechanical properties and tendency toward localized corrosion. These limitations can be effectively addressed by alloying methods. In this study, a ternary Zn-0.4Li-0.4 Mg biodegradable alloy was successfully designed and fabricated using the laser powder bed fusion (LPBF) method. The relative density, microstructural evolution, mechanical and corrosion properties of LPBF-produced Zn-0.4Li-0.4 Mg alloy were systematically investigated. The results indicate that the alloy exhibited a uniform microstructure consisting of fine equiaxed α-Zn grains, with Mg 2 Zn 11 and LiZn 4 phases precipitated along the grain boundaries. Notably, grain size of α-Zn was refined to 4.7 ± 0.07 μm due to the addition of Li and Mg and LPBF process. The as-built specimen shows excellent strength, exhibiting an ultimate strength of 382 MPa, a yield strength of 343 MPa, and a compressive yield strength of 327 MPa, while maintaining structural integrity after 62% compressive deformation. The enhanced strength was mainly attributed to the formation of secondary phases, Mg 2 Zn 11 and LiZn 4 , which contribute significantly to strengthening. In addition, the presence of nanoscale particles provides further strengthening. More interestingly, as-built specimen illustrates a moderate corrosion rate of 97 μm/year after immersing in the Hanks solution for 28 days. As a result, the incorporation of Li and Mg led to a significant improvement in the mechanical and corrosion properties of the Zn matrix. Overall, the Zn-0.4Li-0.4 Mg alloy shows a strong potential candidate for biodegradable implant applications.