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Micro‐electrochemical investigation of the passive behavior of thin anodic titanium oxide films on TiAlV6‐4

: Langklotz, Ulrike; Noeske, Michael; Schneider, Michael


Materials and corrosion 69 (2018), Nr.12, S.1693-1702
ISSN: 0947-5117
ISSN: 0043-2822
ISSN: 1521-4176
Fraunhofer IKTS ()
Fraunhofer IFAM ()
TiAlV6-4; microstructure; anodic oxide film; passivation; passive layer behavior

The present work describes the passive film behavior of thin anodic oxide films on polycrystalline TiAlV6‐4. Firstly, the influence of the microstructure was addressed. Therefore, the crystallographic grain orientations of the substrate were determined by EBSD and selected grains were investigated with an electrochemical micro‐capillary cell. The barrier‐like oxide films were produced by local anodization in an acetate buffered electrolyte (pH 5.9) and investigated by electrochemical impedance spectroscopy and optical reflectometry. Second, the chemical composition of the native oxide film was determined by XPS, and the results related with the micro‐electrochemical experiments. The work shows a strong effect of the basal orientation on the electrochemical behavior. During anodic oxidation, strong electron transfer reactions occur at this orientation, while the enhanced conductivity of the oxide film is also proved by electrochemical impedance spectroscopy. Moreover, a non‐highfield conformal oxide growth and crystallization was observed on the basal plane. These effects, especially the electron conductivity, is related to the incorporation of alloying elements in the passive film.