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Oxidation of Metals

, Volume 35, Issue 5–6, pp 427–439 | Cite as

On the nature of “easy paths” for the diffusion of oxygen in thermal oxide films on aluminum

  • K. Shimizu
  • R. C. Furneaux
  • G. E. Thompson
  • G. C. Wood
  • A. Gotoh
  • K. Kobayashi
Article

Abstract

Thermal oxide films grown on electropolished aluminum specimens have been investigated by transmission electron microscopy of stripped oxide films and ultramicrotomed sections. Particular attention has been focused on the nucleation sites γ-Al2O3crystals and the relationship of such sites to surface features on the electropolished aluminum surface. It is evident that “easy paths” for the diffusion of oxygen, or the nucleation sites of γ-Al2O3crystals, are not distributed randomly over the electropolished aluminum surface, but form preferentially in the amorphous oxide layer grown over preexisting metal ridges. Thus, the diffusion of molecular oxygen through cracks in the amorphous oxide layer represents the most realistic and acceptable basis for explaining the local growth of the γ-Al2O3crystals in thermal oxide films on aluminum, although the cracks have not yet been observed directly.

Key Words

easy diffusion paths Al2O3 films γ-Al2O3 nucleation sites amorphous film 

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Copyright information

© Plenum Publishing Corporation 1991

Authors and Affiliations

  • K. Shimizu
    • 1
  • R. C. Furneaux
    • 1
    • 2
  • G. E. Thompson
    • 1
  • G. C. Wood
    • 1
  • A. Gotoh
    • 2
  • K. Kobayashi
    • 2
  1. 1.Corrosion and Protection CentreUniversity of Manchester Institute of Science and TechnologyManchesterUK
  2. 2.Department of Chemistry, Faculty of Science and TechnologyKeio UniversityYokohamaJapan

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