Gadolinium-tailored Zn-Cu-Li alloys: Enhanced strength, controlled degradation, and cytocompatibility for orthopedic use

Pure zinc (Zn) and Zn alloys exhibit poor strength and weak ductility in their as-cast state, limiting their use in bone implants. Consequently, various alloying elements, such as rare earth elements (REE), and thermomechanical processes such as hot rolling (HR) have been explored to enrich their properties. This study reports the effect of gadolinium (Gd) (0.2–0.6 wt%) on the microstructure, mechanical properties, corrosion resistance, and biocompatibility of a Zn-3Cu-0.2Li (ZCL) alloy prepared via casting and HR. The results showed that Gd addition generated a new secondary phase of GdZn 12 and HR refined the grain size, which together significantly enhanced the strength and the ductility of the ZCL-xGd alloys. The HR ZCL-0.6Gd alloy displayed a tensile yield strength (σ TYS ) of 245 MPa, an ultimate tensile strength (σ UTS ) of 361 MPa, and an elongation (ε) of 33 %. Overall, the HR ZCL-xGd alloys demonstrated superior tensile properties with a σ TYS in the range of 228–248 MPa, σ UTS in the range of 341–371 MPa, and ε in the range of 23–33 %, meeting orthopedic implant requirements. The resistance to corrosion of HR ZCL-xGd alloys decreased as a function of Gd level, with the HR ZCL-0.6Gd showing the highest degradation rate (60.5 μm/y in Hanks’ solution for 30 days). Cytocompatibility tests indicated an insignificant level of toxicity in relation to osteoblast-like SaOS2 cells. The HR ZCL-0.6Gd alloy exhibited optimal strength, biodegradability, and biocompatibility for bone implants. • Mechanical, corrosion & cytotoxicity properties of Zn-3Cu-0.2Li-xGd are studied. • As-cast Zn-3Cu-0.2Li-(0.2–0.6 %) Gd alloys were hot rolled for optimal properties. • Gd addition (∼0.6 %) significantly improved properties of HR Zn-3Cu-0.2Li alloys. • Alloys showed yield strengths of 228–248 MPa, UTS of 341–371 MPa, and ε of 23–33 %. • Enhanced properties exceeded bone implant needs, showing potential for medical use.