Stability domain of alumina thermally grown on Fe–Cr–Al-based model alloys and modified surface layers exposed to oxygen-containing molten Pb

The paper gives experimental results concerning the morphology, composition, structure and thickness of the oxide scales grown on Fe–Cr–Al-based bulk alloys during exposure to oxygen-containing molten lead. The results are discussed and compared with former results obtained on Al-containing surface layers, modified by melting with intense pulsed electron beam and exposed to similar conditions. The present and previous results provide the alumina stability domain and also the criterion of the Al/Cr ratio for the formation of a highly protective alumina layer on the surface of Fe–Cr–Al-based alloys and on modified surface layers exposed to molten lead with 10−6 wt.% oxygen at 400–600 °C. The protective oxide scales, grown on alumina-forming Fe–Cr–Al alloys under the given experimental conditions, were transient aluminas, namely, kappa-Al2O3 and theta-Al2O3. [Display omitted] •The oxidation behaviour of FeCrAl model alloys exposed to molten Pb (+O) was studied.•An oxide map illustrating the stability domains of Al- and Fe-based oxides was drawn.•Cr and Al minimum concentrations necessary to form alumina scale were defined.•Two transient aluminas, κ and θ, were found to grow as protective oxide scale.•The growth rate of θ-Al2O3 was found to be higher than that of κ-Al203.