Corrosion-Associated Mechanical Behavior of Zn-Based Biodegradable Metals During Long-Term In Vitro Immersion Degradation in Hank's Solution
Biodegradable metals (BMs) are designed to corrode gradually in physiological environments, yet this corrosion can compromise their mechanical integrity, potentially causing premature implant failure. For emerging zinc-based alloys, the corrosion-mechanical property relationship remains inadequately characterized. This study systematically investigated the long-term corrosion-associated mechanical behavior of hot-extruded Zn-Cu and Zn-Cu-Fe alloys, promising Zn-based bio-metals, in comparison with pure Zn, under immersion degradation in Hank's solution. Electrochemical impedance spectroscopy and mechanical testing revealed that the evolving corrosion profile governs mechanical performance. Alloying with Cu and Fe mitigated corrosion's detrimental effects: grain refinement reduced localized corrosion susceptibility, while finely dispersed second phases acted as cathodic sites, promoting uniform corrosion. Additionally, Cu and Fe facilitated the formation of protective corrosion product layers, suppressing further matrix attack. Consequently, the overall reduced corrosion, particularly localized corrosion, lowered stress concentration susceptibility, delaying mechanical decline and preserving structural integrity. These findings elucidate the degradation-mechanical property correlation in Zn-based bio-metals and underscore critical considerations for developing new bio-metals for clinical translation.