Air oxidation of FeCoNi-base equi-molar alloys at 800-1000°C

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • W. L. Jang
  • R. T. Huang
  • C. C. Lee
  • H. H. Hsieh
  • C. F. Du

Detail(s)

Original languageEnglish
Pages (from-to)169-192
Journal / PublicationOxidation of Metals
Volume63
Issue number3-4
Publication statusPublished - Apr 2005
Externally publishedYes

Abstract

The oxidation behavior of FeCoNi, FeCoNiCr, and FeCoNiCrCu equi-molar alloys was studied over the temperature range 800-1000 °C in dry air. The ternary and quaternary alloys were single-phase, while the quinary alloy was two-phase. In general, the oxidation kinetics of the ternary and quinary alloys followed the two-stage parabolic rate law, with rate constants generally increasing with temperature. Conversely, three-stage parabolic kinetics were observed for the quaternary alloy at T ≥ 900°C. The additions of Cr and Cu enhanced the oxidation resistance to a certain extent. The scales formed on all the alloys were triplex and strongly dependent on the alloy composition. In particular, on the ternary alloy, they consist of an outer-layer of CoO, an intermediate layer of Fe3 O 4, and an inner-layer of CoNiO2 and Fe3O4. Internal oxidation with formation of FeO precipitates was also observed for this alloy, which had a thickness increasing with temperature. The scales formed on the quaternary alloy consisted of an outer layer of Fe3O4 and CoCr 2O4, an intermediate layer of FeCr 2 O 4 and NiCr2O4, and an inner layer of Cr 2O3. Finally, the scales formed on the quinary alloy are all heterophasic, consisting of an outer layer of CuO, an intermediate-layer of CuO and Fe3O4, and an inner-layer of Fe3O 4, FeCr2O4, and CuCrO2. The formation of Cr2O3 on the quaternary alloy and possibly that of CuCrO2 on the quinary alloy was responsible for the reduction of the oxidation rates as compared to the ternary alloy. © 2005 Springer Science+Business Media, Inc.

Research Area(s)

  • Equi-molar alloys, Fe-Ni-Co-Cu-Cr, Oxidation

Bibliographic Note

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Citation Format(s)

Air oxidation of FeCoNi-base equi-molar alloys at 800-1000°C. / Kai, W.; Jang, W. L.; Huang, R. T.; Lee, C. C.; Hsieh, H. H.; Du, C. F.

In: Oxidation of Metals, Vol. 63, No. 3-4, 04.2005, p. 169-192.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review