Microstructure, corrosion behavior and cytotoxicity of Zr–Nb alloys for biomedical application

In this work, the effects of Nb content on microstructure and corrosion behaviors of biomedical Zr–Nb alloys were systematically studied. The results of XRD analysis and optical microscopy indicated that the experimental Zr–Nb alloys had a duplex structure of α and β phases, and the content of β phase increased with the increase of Nb content. The electrochemical impedance spectroscopy (EIS) studies showed an improvement on the resistance of the spontaneous oxide film with increasing Nb content. The EIS data, fitted by Rs(QpRp) model, suggested a single passive film formed on the experimental material surfaces. Polarization tests in Hankʹs solution revealed a nobler electrochemical behavior of the Zr–Nb alloys after alloying Nb to pure Zr. The corrosion resistance increased with increasing Nb content, as indicated by lower corrosion current densities and passive current densities and higher pitting potentials. The major components on the surfaces of the corroded Zr–Nb alloy samples detected by XPS were ZrO2 and Nb2O5. The biocompatibility of Zr–Nb alloys was primarily evaluated by culturing L-929 cells in the extraction media of Zr–Nb alloy samples and excellent results were obtained. All of these above results suggested that the Zr–22Nb alloy, among the experimental alloys, showed a promising potential for biomedical applications.