Original Article

Influence of minor Fe addition on the corrosion behavior of Zn–6Cu alloys for biodegradable implant Applications

Computational and Experimental Materials Innovation Group (CEMIG), Department of Metallurgical Engineering, NED University of Engineering and Technology, University Road, Karachi 75270, Pakistan

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Received: 2 October 2025
Accepted: 6 July 2026

Abstract

This study investigates the effect of minor iron (Fe) additions on the corrosion behavior of Zn–6Cu alloys for potential use in biodegradable implant applications. Alloys with compositions Zn–6Cu–xFe (x = 0.16 and 0.22 wt.%) were synthesized via induction melting, with pure Zn as a reference. Phase identification was carried out via X-ray diffraction (XRD). Electrochemical measurements in physiological saline solution were conducted to assess charge transfer resistance, double-layer capacitance, corrosion current density, and corrosion rate. -XRD confirmed the presence of η-Zn, CuZn₅, and FeZn₁₃ phases, indicating that Fe participates in the formation of distinct intermetallic compounds. Results of potentiodynamic polarization and electrochemical impedance spectroscopy indicate that Fe addition significantly influences corrosion mechanisms. The Zn–6Cu–0.16Fe alloy demonstrated the lowest corrosion rate and highest impedance among the studied samples, indicating suppressed electrochemical activity and enhanced corrosion resistance without forming a passive film. In contrast, the Zn–6Cu–0.22Fe alloy exhibited a transient passive film accompanied by a measurable pitting potential, suggesting a transition from uniform corrosion to localized attack at higher Fe content. Both Fe-containing alloys outperformed pure Zn in corrosion performance; however, the alloy with 0.16 wt.% Fe proved most effective in achieving controlled and uniform degradation in physiological saline. These results underscore the importance of precise Fe addition in Zn–Cu alloys for biodegradable implants, where a lower Fe content improves corrosion resistance by inhibiting active dissolution, while higher Fe content may promote passivation but with an increased risk of localized corrosion in chloride-rich environments.