Additively manufactured Zn–Mg alloys as orthopedic implants: effects of laser power and scanning rates

Additive manufacturing of biodegradable metals enables patient-specific orthopedic implants that can resorb in vivo and avoid removal surgery. Among candidates, Zn–Mg alloys balance Zn’s limited bioactivity with Mg’s rapid corrosion. The enhanced osteogenesis has been demonstrated through additive manufacturing of Zn-Mg alloys scaffolds. However, the effects of processing parameters (laser power and scanning rates) on microstructures, mechanical properties, degradation, and osteogenesis are not systemically investigated. Here we fabricate Zn–3Mg alloys by laser powder bed fusion (L-PBF). Porosities of additively manufactured Zn-Mg alloys are decreased, achieving high yield strength (compression) over 600 MPa at a 70 W laser power and a 600 mm/s of scanning rate. Corrosion rates are reduced to ∼0.1 μm/day by forming dense degradation products on the surface of Zn-Mg alloys. In vitro and in vivo studies show markedly improved bone regeneration compared with bioinert Ti. This benefit correlates with reduced release of Zn 2+ and Mg 2+ , enhancing cytocompatibility and promoting osteogenic differentiation. These results clarify processing parameters–microstructures–properties–biology relationships in biodegradable Zn-based alloys and provide guidance for engineering next-generation orthopedic implants.