Phase Transformation and Growth of Alumina on a Thin FeCrAl-RE Foil at around 900°C

El Kadiri, H., Molins, R., Bienvenu, Y., & Horstemeyer, M. (2005). Phase Transformation and Growth of Alumina on a Thin FeCrAl-RE Foil at around 900°C. Materials Science Forum. Les Embiez-France: Trans Tech Publications Ltd, Zurich-Ueticon, CH-8707, Switzerland. 461, 1107-1116.

We performed isothermal oxidation tests on a 95μm thin commercial FeCrAl foil at around 900°C in ambient and synthetic air in order to examine the effects of microstructural and morphological evolution of metastable aluminas on the overall growth kinetics by mean of TGA, AET, FEG-SEM, TEM, EPMA and GIXRD techniques. The origin of platelet-like morphology formation at an early stage of oxidation is examined and discussed. Further heating produces phase transformation and significant structural changes of this morphology. Formation of a corundum-alumina-rich compact layer from an outer metastable layer by a coupling phenomenon between grain growth and the sintering of the platelets was identified as responsible of the discontinuous increase in growth rate at around 900°C widely reported in the literature.