The Oxidation Behaviour of the Commercial FeCrAlRE Alloys Aluchrom YHf and Kanthal AF Foils in Air at 800°-950°C

The oxidation behaviour of 30mum and 50mum thick Aluchrom, YHf and 50mum thick Kanthal AF foils have been examined during discontinuous exposure (with 100h cycles) to laboratory air at 800, 850, 900 and 950degreesC. Oxidation was continued out to 3000h or until breakaway ensued, whichever was the shorter. Resulting observations include two oxidation temperature domains, a two-stage oxidation process leading to a duplex alumina scale and at breakaway, a distinct chromia inner layer underlying the alumina outer layers. To unravel the underlying mechanisms involved, the scales were examined by a range of surface analytical techniques, including optical and scanning electron microscopy, together with Energy Dispersive X-ray analysis and X-ray diffraction.