LAUSR

Abstract Porous electrochemically prepared α-phase Ti-5Ta-2Nb (TTN) alloy and dense commercial titanium of grade cp-4 were corrosion tested in concentrated nitric acid. This comprised potentiodynamic polarisation measurements in 9 and 11.5 M acids at ambient temperature and corrosion rate measurements in 15.3 M boiling acid both of which indicated spontaneous passivation behaviour. Extensive materials characterisation, including X-ray diffraction, electron microscopy, energy-dispersive spectroscopy and X-ray photoelectron spectroscopy, revealed that the passivation was due to the formation of a protective oxide film. TTN alloy of low porosity was found to have an average corrosion rate of only 0.076 mm/y which is far superior to that of dense Ti cp-4 at 0.774 mm/y. The results underscore why TTN alloy is currently being considered as a candidate material for structural applications in the reprocessing of spent oxide nuclear fuel and that its electrochemical synthesis route may offer advantages over the conventional ones.