A combined electrochemical and XPS study on the passivity of B2 iron aluminides in sulphuric acid solution

S. Frangini, N.B. De Cristofaro, A. Mignone, J. Lascovich, R. Giorgi

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Abstract

The effect of aluminium alloying on the passivation properties of iron has been evaluated on a B2 FeAl intermetallic alloy in 1 N H2SO4by a combination of electrochemical and surface analytical techniques. A clear improvement of the protective properties of the passive films formed on FeAl compared with iron is found. XPS analysis of the surface films has shown that passivation of FeAl is accomplished by a strong enrichment of aluminium within the film. The structure of the passive film is considered to be bilayered with the outer part composed of precipitated mixed aluminium-iron oxy-hydroxide and the inner part composed mostly of an aluminium-rich oxide phase which is responsible for the onset of passivity. The stabilizing effect of aluminium on the passive properties of iron has been ascribed mainly to the formation of a passivating film whose characteristics are greatly modified by the presence of aluminium ions in the lattice. This is suggested to favour the development of a more amorphous film with enhanced protective characteristics, through improved structural flexibility of the metal-oxygen bond. © 1997 Elsevier Science Ltd.
Original languageEnglish
Pages (from-to)1431 - 1442
Number of pages12
JournalCorrosion Science
Volume39
Issue number8
DOIs
Publication statusPublished - 1997

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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