Biodegradable Zn-0.5Li alloys with supersaturated solid solution-aging treatment for implant applications

To solve the problems of poor mechanical properties and local corrosion caused by the coarse dendrites grain and the second phase of as-cast (AC) Zn-Li alloy, AC Zn-0.5Li alloys were treated by ultra-high pressure (3 GPa) solid solution-aging treatment (UHPS-AT) at 375 & DEG;C. The microstructure, mechanical, corrosion behavior, cell compatibility, and anti-bacterial properties of UHPS-AT Zn-0.5Li alloys were characterized and evaluated. After the UHPS-AT treatment, the TEM images showed the presence of large Zn/b-LiZn4 layered grain inside UHPS-AT alloy, and the dendritic grain and coarse second phase disappeared. The mechanical properties and wear resistance of Zn-0.5Li alloys were improved compared with AC alloys after UHPS-AT treatment. However, the compressive yield strength of UHPS Zn-0.5Li alloy decreased after aging, indicating that the strengthening effect of solid so-lution is better than that of the second phase precipitation, which was also proved by theoretical calculation. A dense passivation film was formed on the surface of the UHPS-AT sample, hindering further corrosion of the alloy, resulting in the change of the corrosion mechanism from local corrosion in the as-cast state to uniform corrosion in the UHPS-AT state. Cytotoxicity assays with Zn-0.5Li alloys showed that extracts at concentrations below 12.5% were not cytotoxic. Moreover, the Zn-0.5Li alloy exhibited good antibacterial properties against E. coli bacteria.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).