Oxidation of γ-Ni-Al-Si alloys at 1073 K

H. C. Yi, San-Qiang Shi, W. W. Smeltzer, A. Petric

Research output: Journal article publicationJournal articleAcademic researchpeer-review

19 Citations (Scopus)

Abstract

The formation and development of oxides in Ni-4Al and Ni-4Al-xSi (at.%, x=1, 3, 5) alloys at 5-9×10-6 and 1 atm oxygen pressure at 1073 K have been studied. The oxidation rate increased with an increase of silicon content in the alloy at the early stage of oxidation, but decreased after longer time exposure due to formation of an intermediate layer composed of NiO and spinel (NiAl2O4 and Ni2SiO4) between the top NiO layer and the internal-oxidation zone. This intermediate layer became a barrier for releasing stress, generated by the volume expansion associated with oxidation of solute atoms, resulting in high dislocation density and severe distortion in the internal-oxidation zone for the Ni-Al-Si alloys. In Ni-4Al alloy where no complete intermediate-layer formation occurred, stress was easily released by an enhanced vacancy gradient, and therefore an enhanced vacancy-injection rate into the alloy, resulting in a higher oxidation rate than the situation where a sample was oxidized at an oxygen pressure associated with the dissociation of NiO.
Original languageEnglish
Pages (from-to)115-139
Number of pages25
JournalOxidation of Metals
Volume43
Issue number1-2
DOIs
Publication statusPublished - 1 Feb 1995
Externally publishedYes

Keywords

  • internal oxidation
  • Ni-Al-Si alloys
  • stress release

ASJC Scopus subject areas

  • Metals and Alloys
  • Inorganic Chemistry
  • Materials Chemistry

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