Internal oxidation of Fe-Al alloys in the α-phase region

Jun Takada, Sadahiro Yamamoto, Shiomi Kikuchi, Masao Adachi

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49 Citations (Scopus)

Abstract

The internal oxidation behavior of Fe-0.069, 0.158, and 0.274 wt% Al alloys was investigated in the α-phase region. The internal oxidation experiments have been made over the temperature range from 1023 to 1123 K using a mixture of iron and its oxide powders. A parabolic rate law holds in the present alloys, where the rate constant, Kp, depends upon the oxidation temperature as well as the aluminum content. The internal oxidation of Fe-Al alloys is, therefore, controlled by a diffusion process of oxygen in the alloy. The oxide formed in the oxidation layer is the stoichiometric FeAl2O4 (hercynite). The aluminum concentration, NAlIo, in the oxidation layer was calculated by taking account of counterdiffusion of aluminum. Furthermore, the oxygen concentration, NOS, at the specimen surface was evaluated on the basis of thermodynamics. Using these estimated values of Kp, NAlIO, and NOS, the diffusion coefficient of oxygen, DOIO, in the oxidation layer, where the oxide particles were dispersed, was also calculated. DOIO increases as the volume fraction of the oxide, fIO, increases. The diffusion coefficient of oxygen, DO, in α-iron was determined by extrapolating DOIO to fIO=0.

Original languageEnglish
Pages (from-to)93-105
Number of pages13
JournalOxidation of Metals
Volume25
Issue number1-2
DOIs
Publication statusPublished - Feb 1 1986

Keywords

  • counterdiflusion
  • diffusion coefficient of oxygen
  • internal oxidation
  • oxygen solubility
  • α-iron

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Metals and Alloys
  • Materials Chemistry

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  • Cite this

    Takada, J., Yamamoto, S., Kikuchi, S., & Adachi, M. (1986). Internal oxidation of Fe-Al alloys in the α-phase region. Oxidation of Metals, 25(1-2), 93-105. https://doi.org/10.1007/BF00807998