Electrochemical properties, chemical composition and thickness of passive film formed on novel Ti–20Nb–10Zr–5Ta alloy

Abstract

The properties of a novel, quaternary Ti–20Nb–10Zr–5Ta alloy were investigated in relation to its use in biomedical applications. Its microstructure was revealed by X-ray diffraction, and composition by energy dispersive X-ray measurements. Electrochemical oxidation in three simulated physiological solutions, 0.9% NaCl, Hanks’ physiological solution and minimum essential medium, was studied and compared to the behaviour of its individual metal components. Its electrochemical behaviour is similar to those of tantalum and niobium and is superior to those of titanium and, especially, zirconium. The superior corrosion protectiveness in physiological solution was ascribed to the formation of a complex oxide layer. The composition of the latter was studied as a function of formation potential, using X-ray photoelectron spectroscopy. The layer is comprised predominantly of titanium oxide but also contains oxides of alloying elements. The incorporation of alloying oxides in the passive layer is probably the basis for the exceptional protectiveness of this alloy under simulated physiological conditions. These characteristics form the basis of a great potential for the use of Ti–20Nb–10Zr–5Ta alloy in biomedical applications.