Microstructure of aluminium oxide formed on ferritic FeCrAl alloy after high-temperature steam oxidation

Abstract

ABSTRACTThe growth of Al2O3 scale during the short-duration oxidation of ferritic FeCrAl alloy containing a small amount of reactive elements added as oxide dispersions was investigated. The test specimens of the FeCrAl alloy were oxidised isothermally for 100 s, 3 h or 24 h at 1200°C under steam environment. The time-dependent changes in the scale microstructure and composition were carefully observed. All of oxidised specimens were covered by a continuous α-Al2O3 scale without the spallation of the scale. A comparison is also made to a FeCrAl model alloy with lower Cr content and Y added in metallic form. In addition, the oxygen grain boundary diffusivity across the α-Al2O3 scale was estimated based on the growth and microstructure of the Al2O3 scales and compared to those reported in the existing literature.