Many studies have been devoted to the oxidation of FeCrAl alloys in the intermediate temperature range 850-950°C, where ''abnormal'' oxide growth is observed [1][2][3]. This phenomenon has been described as a transition period in which the outward growth of metastable cubic aluminas is more rapid than the inward growth of the stable rhombohedral a-alumina, which effectively protects this type of alloy up to 1200°C. The consequently more rapid consumption of aluminum from the alloy due to metastable Al 2 O 3 growth is particularly detrimental in situations where thin metallic foils have to be used, as in the case of catalyst supports in exhaust systems of combustion engines [4][5][6], and has to be understood and suppressed or reduced.Previous studies have generally concluded that the transient metastable aluminas, characterized to be c, d and/or h modifications depending on alloy, temperature and characterization technique used [7], quickly form in the first minutes of oxidation and grow showing typical needle or platelet shapes. Kinetics follow near parabolic behavior, with high rate constants (k p s), extensively reported in the literature; see for example [8]. These alumina modifications are all stable regarding their formation

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International audienceThe influence of surface preparation on the stress and adhesion of oxide scales formed on the ferritic stainless steel AISI 441 was studied. Steel coupons were surface-finished to different degrees of surface roughness from 400-grit SiC through to 1-micron diamond, and were also electropolished to remove the work hardened surface. Initial metal roughness was measured by optical profilometry. Oxidation was carried out at 800 degrees C under synthetic air for 100 h. Oxide residual stress was derived from the Raman shift of the main chromia line, and adhesion of oxide scales was quantitatively obtained using forced spallation by tensile straining. The results show that surface hardening is the most influential factor on adhesion, with the high dislocation-containing mirror-polished samples exhibiting the lowest adhesion energy (similar to 4 J m(-2)), and the electropolished samples with non-mechanically affected surface exhibiting the highest adhesion energy (17 J m(-2)). Recrystallisation of the subsurface zone during heating to the oxidation temperature is thought to be the most influential factor reducing scale adhesi

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