Electrochemical behavior of an alpha-phase titanium alloy in oxidizing nitric acid environments: Influence of an oxygen-enriched layer

ABSTRACT The study focuses on establishing the influence of an oxygen-enriched layer (OEL) on the electrochemical properties of an alpha-phase titanium alloy, Ti-Al-Zr, in oxidizing nitric acid environments. Heat treatment was given to the material at 760 °C for 700 h in air which resulted in the formation of an OEL on the surface. The electrochemical properties were studied and compared with as-received (AR) conditions by techniques like open circuit potential (OCP), potentiodynamic polarization, chronoamperometry and electrochemical impedance spectroscopy measurement. It was established that the presence of an OEL on the surface reduced the cathodic activity of oxidizing species on the material’s surface. The OCP value did not depend on the presence/absence of the OEL on the surface. The formation of the passive film was instantaneous for all conditions. The presence of the OEL on the surface promoted the formation of a protective passive film. The material with an OEL on the surface had a lower donor density as compared to the AR condition.