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Z. Werner, A. Jaskiewicz, M. Pisarek, M. Janik-Czachor, M. Barlak

AES and RBS Characterization of Anodic Oxide Films on Al-Ta Amorphous Alloys

Keywords: Anodic Films, Amorphous Alloys, Al-Ta Alloys

Anodic layers grown on Al-Ta sputter deposited amorphous alloys were studied by electrochemical methods, AES, and RBS. The alloy composition ranged from Al₉₀Ta₁₀ to Al₇₀Ta₃₀. It has been found that an increase of breakdown potential E_np′ caused by refractory metal content extends over a wide concentration range from 0.01 M up to 1 M NaCl.
AES measurements have shown that Ta remains in an oxidized state over the whole thickness of the anodic layer thus confirming the model of Ta acting as a passivity promoter rather than a dissolution moderator.
RBS results clearly demonstrate that in low Ta content layers a thin alumina film is formed on the top surface of the anodic layer. For higher Ta content only a depletion in Ta is observed on the surface. The latter result differs from those obtained previously by other authors and may be caused by differences in experimental conditions and/or the alloy structure.
The role of refractory metals in the passivity of Al-based amorphous alloys is discussed.

Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag

Print ISSN: 0942-9352
Volume: 219, 11/2005
Pages: 1461 - 1479

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