The effect of yttria coatings on the oxidation behaviour of Fe-25Al and Ni-32Al at 1100 and 1200 °C

R. Prescott; D.F. Mitchell; J.W. Fraser; M.J. Graham

doi:doi:10.1051/jp4:1993929

Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température

J. Phys. IV France 03 (1993) C9-301-C9-308
DOI: 10.1051/jp4:1993929

The effect of yttria coatings on the oxidation behaviour of Fe-25Al and Ni-32Al at 1100 and 1200 °C

R. Prescott, D.F. Mitchell, J.W. Fraser and M.J. Graham

Institute for Microstructural Sciences, National Research Council, Ottawa, K1A 0R6, Canada

Abstract
The influence of Y₂O₃ coatings on the oxidation behaviour of Fe-25wt%Al and Ni-32wt%Al has been investigated at 1100 and 1200 °C. Samples were sputter coated with 4 nm of Y₂O₃ and oxidized sequentially in ¹⁶O₂ and ¹⁸O₂. Oxide scales have been characterized using SIMS, XPS, SEM, X-ray and electron diffraction. A comparison is made between the growth of oxide on Y₂O₃-coated and uncoated alloys. The major effects of the yttria coating at 1100 °C are to delay the formation of α-Al₂O₃ and to increase the oxidation rate. At 1200 °C a two-layered scale is formed instead of a single layer; all of the yttrium is contained in a non-adherent outer layer.