High temperature oxidation of Fe-Al alloys studied by in situ x-ray diffraction

The high temperature oxidation of Fe-Al alloys with Al contents from 5 to 30% was studied at 900 degrees C by high temperature X-ray diffraction. The technique allows the in situ identification of the oxidation products and of their modifications and yields information about their formation kinetics. A protective alpha-Al2O3 scale was formed on Fe-Al alloys with 30 and 20% Al. The Fe-Al alloy with 10% Al forms alpha-Fe2O3 besides of alpha-Al2O3 and the alloy with 5% Al forms at 900 degrees C alpha-Fe2O3 and no alumina. The formation of the oxides is observed simultaneously at each state of the oxidation yielding the qualitative formation kinetics for each oxide.