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The new Ti-15Ta-5Zr alloy revealed a homogeneous bi-phase α + β microstructure without inclusions or secondary phases. The alloy native passive film contains both Ti2O3, and TiO2 oxides and very resistant Ta2O5 and ZrO2 oxides (X-ray photoelectron spectroscopy). All main electrochemical and corrosion parameters in artificial Carter-Brugirard saliva had more favourable values than those of Ti and other implant alloys, due to the Ta and Zr alloying elements, which contributed with their protective oxides to the native passive film and due to the alloy very homogeneous microstructure. Impedance spectra indicated a passive film formed by two layers: an inner, insulating, barrier layer that provides the high corrosion resistance and an outer, porous, less protective layer that permits the absorption of ions and species from surrounding environment into its pores, favouring both interaction and bioactivity. X-ray photoelectron spectroscopy and scanning electron microscopy detected new depositions (Na3PO4 and K3PO4 protective compounds) of 5 nm thickness on the alloy surface after 1000 h in Carter-Brugirard saliva, which confer to the substrate both corrosion resistance and bioactivity. [ABSTRACT FROM AUTHOR]

In this paper, we applied the potentiostatic anodisation method on the new Ti-20Nb-10Zr-5Ta alloy surface with the aim to increase its stability and bioactivity. The morphology (SEM) and composition (Raman, FT-IR) of the obtained anodisation nanolayer are studied. Also, electrochemical stability (by cyclic potentiodynamic polarisation and EIS), corrosion resistance (by linear polarisation), long-term behaviour (by monitoring of the open circuit potentials and corresponding open circuit potential gradients) and the characterisation of the layers deposited on the alloy surface after 1000 h in acid, neutral and alkaline Ringer and neutral Ringer-Brown solutions are presented. By potentiostatic anodisation, on the alloy surface was electrodeposited a continuous nanolayer containing TiO2 rutile type oxide. The anodised layer possesses better protective properties and at the same time better porosity, therefore a higher stability and bioactivity in comparison with the native passive film. After 1000 h in the testing solutions promoted the deposition of the brushite, phosphatotitanate and hydroxyapatite, precursors, respectively component of the human bone, namely this layer is bioactive. [ABSTRACT FROM AUTHOR]