Structure and growth mechanism of anodic films formed on magnesium die cast AZ91D

S. Ono*, M. Saito, M. Horiguchi, K. Terashima, K. Matsusaka, A. Shida, T. Osaka, N. Masuko

*Corresponding author for this work

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10 Citations (Scopus)


The structure and the growth mechanism of anodic oxide films grown on magnesium die cast AZ91D have been studied by electron microscopy combined with an ultramicrotomy technique. The anodic films are highly uneven in thickness. This may have been caused by film destruction resulting from breakdown accompanied by gas evolution, and also by uneven anodic reaction owing to the presence of cavities and compositional irregularities at the grain boundaries. Porous cell structure with dispersed MgF2 and NaMgF3 crystalline particles is found in the films. It is assumed that anodic film growth proceeds by the formation of MgF2 and magnesium oxyhydroxide at the metal/film interface and the dissolution of the film at the pore bases. The crystallization of MgF2 and the formation of NaMgF3 subsequently proceed in the porous layer.

Original languageEnglish
Pages (from-to)268-272
Number of pages5
JournalHyomen Gijutsu/Journal of the Surface Finishing Society of Japan
Issue number3
Publication statusPublished - 1996

ASJC Scopus subject areas

  • Engineering(all)


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