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Journal of Materials Science

, Volume 19, Issue 10, pp 3451–3458 | Cite as

Internal oxidation of Fe-Si alloys in γ-phase region

  • Jun Takada
  • Ken Kashiwagi
  • Masao Adachi
Papers

Abstract

Internal oxidation measurements of Fe-0.070, 0.219, 0.483, and 0.920 wt % Si alloys were made in the γ-phase region in order to discuss kinetics of internal oxidation, to evaluate the diffusion coefficient of oxygen in the internal oxidation layer, and to determine the diffusion coefficient of oxygen in γ-iron. Internal oxidation of these alloys was conducted at temperatures between 1223 and 1323 K using a powder mixture of iron and Fe2O3. The internal oxidation front in Fe-Si alloys with between 0.070 and 0.483 wt % Si advances in parallel to the specimen surface. The internal oxidation in these alloys obeys a parabolic rate law, which indicates that the internal oxidation is controlled by an oxygen diffusion process in the alloy. The diffusion coefficient of oxygen, D O IO , in the internal oxidation layer where SiO2 particles disperse was determined by using the thermodynamic data for the solution of oxygen in γ-iron. D O IO increases with the increase of the volume fraction of the oxide, fIO, in the oxidation layer at a given temperature. The diffusion coefficient of oxygen, DO, in γ-iron was evaluated by extrapolating D O IO to fIO=0. DO may be given by the following equation:
$$D_O = \left( {6.42\begin{array}{*{20}c} { + 4.37} \\ { - 2.60} \\ \end{array} } \right) \times 10^{ - 5} exp \left[ { - \frac{{159 \pm 5(kj mol^{ - 1} )}}{{RT}}} \right]m^2 \sec ^{ - 1} $$
.

Keywords

Fe2O3 Diffusion Coefficient Specimen Surface Powder Mixture Oxygen Diffusion 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman and Hall Ltd. 1984

Authors and Affiliations

  • Jun Takada
    • 1
  • Ken Kashiwagi
    • 1
  • Masao Adachi
    • 1
  1. 1.Department of Metal Science and TechnologyKyoto UniversityKyotoJapan

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