Isothermal Oxidation of FeAl Intermetallics in Oxygen and Air

The oxidation kinetics of FeAl Intermetallics in ambient atmosphere and dry oxygen at the temperature range of 1000 - 1200 C were investigated. Oxide products were examined by using X-ray diffraction. The morphologies of the oxidised specimens were studied by using Scanning Electron Microscopy and Atomic Force Microscope. The microcompositions on the specimens after oxide scale spallation were analysed by using X-ray Photoelectron Spectroscopy. The results showed that the oxidation rates for the specimens oxidised in air were faster than those in oxygen. The oxide scales have a two-layer structure: a top crystalline CI-AI2O3 oxide layer and an inner amorphous/nano-crystal oxide layer. Nitrogen can be detected from the inner amorphous/nano-crystal oxide layer on the specimen oxidised in air. The specimens oxidised in both air and dry oxygen showed spallation during the cooling stage. Based on the experimental results, isothermal oxidation kinetics of FeAl in air and in dry oxygen were compared and analysed. The mechanisms of the formation and spallation of the oxide scale were discussed.