Influence of Alkaline Earth Barium on the Microstructure, Corrosion Behavior, and Cytocompatibility of Biodegradable Zinc

ABSTRACT

Biodegradable Zn‐based alloys are promising candidates for temporary implants, yet excessive Zn ²⁺ release during degradation may induce cytotoxicity and adverse tissue responses. In this study, Zn‐ x Ba alloys ( x  = 0.1 wt%, 0.5 wt%, 1.0 wt% and 3.0 wt%) were developed to achieve controlled corrosion behaviors with improved biocompatibility. The alloys were fabricated by vacuum induction melting followed by hot extrusion, and their microstructures, corrosion behaviors, and in vitro cytocompatibility were systematically evaluated. Ba addition promoted the formation of BaZn ₁₃ phase and refined the grain structure, whereas micro‐galvanic interactions between the BaZn ₁₃ particles and Zn matrix significantly accelerated corrosion. The corrosion rate increased from 7.97 μm year ⁻¹ for pure Zn to 14.17 and 48.93 μm year ⁻¹ for Zn‐0.1Ba and Zn‐3.0Ba during 30‐day immersion. After 90 days, the corrosion rates decreased to 1.08–5.13 μm year ⁻¹ due to the shielding effect of corrosion products, and yet Zn‐ x Ba alloys still degraded faster than pure Zn. ICP‐MS analysis showed preferential Ba release with reduced Zn ²⁺ release, owing to the selective dissolution of BaZn ₁₃ . The Ba ²⁺ concentration remained below its cytotoxic threshold, and Zn‐ x Ba alloys exhibited comparable or even improved cytocompatibility compared with that of pure Zn. These results demonstrate that proper Ba alloying balances the trade‐off between corrosion rate and biocompatibility of biodegradable Zn, which will provide some new ideas in the research and development of novel biodegradable Zn alloys with better performances.