Analytical electron-microscopy study of the breakdown of α-Al2O3 scales formed on oxide dispersion-strengthened alloys

B. A. Pint, A. J. Garratt-Reed, L. W. Hobbs

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Abstract

Alumina scales formed during cyclic oxidation at 1200°C on three Y2O3-Al2O3-dispersed alloys: Ni3Al, β-NiAl, and FeCrAl (Inco alloy MA956) were characterized. In each case, the Y2O3 dispersion improved the α-Al2O3 scale adhesion, but in the case of Ni3Al, an external Ni-rich oxide spalled and regrew, indicating a less-adherent scale. A scanning-transmission electron microscope (STEM) analysis of the scale near the metal-scale interface revealed that the scale formed an ODS FeCrAl showed no base metal-oxide formation. However, the scale formed on ODS Ni3Al showed evidence of cracking and Ni-rich oxides were observed. The microstructures and mechanisms discussed may be relevant to a thermal-barrier coating with an Al-depleted aluminide bond coat nearing failure.

Original languageEnglish
Pages (from-to)119-145
Number of pages27
JournalOxidation of Metals
Volume56
Issue number1-2
DOIs
StatePublished - 2001

Keywords

  • Adhesion
  • AlO
  • High-temperature oxidation
  • ODS alloys
  • Reactive-element effect

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