Parameters affecting transient oxide formation on FeCrAl based foil and fibre materials

The effects of oxidation temperature and atmosphere on the formation of alumina scales on two commercial FeCrAl foil materials have been investigated. The oxidized specimens were characterized using a range of surface analysis techniques including SEM, XRD, laser induced optical spectrometry (LIOS), AES and XPS. During oxidation at temperatures exceeding 1000degreesC, the protective oxide scales formed on FeCrAl-alloys consist mainly of alpha alumina. At lower temperatures, however, formation of transient alumina modifications, has been observed. Although after longer oxidation times transformation into the stable alpha alumina occurs, the high initial growth rate of the metastable oxide phases could lead to a critical depletion of the Al-reservoir in thin walled (e.g. 20 (m) components, resulting in early breakaway failure. The occurrence of metastable oxides cannot simply be correlated with alloy composition.