Air oxidation of commercial FeCrAlRE alloy foils between 800 and 950°C

The oxidation behaviour of 30 mu m and 50 mu m thick Aluchrom YHf and 50 mu m thick Kanthal AF foils have been examined during discontinuous exposure (100 h cycles) to laboratory air at 800, 850, 900 and 950 degrees C. Oxidation was continued out to 3000 h or until chemical failure ensued, whichever was the shorter. Resulting observations include two oxidation temperature domains, a two-stage oxidation process leading to a duplex (transitional-alpha) alumina scale and ultimately, a two-stage chemical failure process of the oxide scale leading to brealkaway/non-protective attack. To unravel the underlying mechanisms involved, the scales were examined by a range of microscopy and analytical techniques, including optical and scanning electron microscopy (SEM), electron microprobe analysis (EPMA), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD).