Effects of Al Addition and Minor Elements on Oxidation Behaviour of FeCr Alloys

Abstract
It is shown that the addition of aluminium is very effective for the high temperature oxidation resistance of FeCr alloys. 1% aluminium produces a continuous protective Al₂O₃ oxide for FeCr alloy that contains more than 13% of chromium. However this aluminium content is not enough for the high temperature resistance of thin foils and a 5% aluminium content is needed since the substrate plays the role of an aluminium reserve susceptible to oxidation. Impurity elements such as sulphur are detrimental and give rise to scaling of the oxide layer. Active elements such as Y, Ce, La, Zr are therefore necessary to tie up sulphur and increase the life of the alloys.