Cyclic oxidation behavior of Fe-40Al sheet

The cyclic oxidation behavior of a 200 μm thick Fe-40at.%Al sheet was investigated at 1373 K in air for up to 63 cycles. A compact and adherent α-Al2O3 scale formed on the sheet. Scale cracks with tensile crack features developed due to thermal stress, but these were repaired by forming new α-Al2O3 scale beneath the cracks. Simultaneously, the creep strain of Fe-40Al sheet was also observed to increase with the number of oxidation cycles. The EPMA results show that no obvious Al depletion zone formed in the sheet, and that the Al content in the substrate decreased from the original 39.2 to 37.6 at.% after 63 cycles. The Al content of a commercial 50 μm thick Fe-20Cr-11Al (at.%) foil decreased from the original 11.1 to 1.1 at.% after 63 cycles, with no oxide scale cracks development.