Evolution of oxide scales on an ODS FeAl intermetallic alloy during high temperature exposure in air

The oxide dispersion strengthened FeAl Grade 3 intermetallic alloy have been shown to develop a structured oxide scale upon isothermal oxidation between 850 and 950 °C for 24 h. Transmission electron microscopy studies have revealed a top nanoequiaxed alumina, alumina and Fe-Al spinel at the outer, central and internal layers, respectively. At 1000 °C, the spinel phase no longer forms but a columnar alumina layer topped by a nanoequiaxed structure. The role of yttria is negligible at lower temperatures whereas some segregation at the scale/substrate interface and precipitation of YAlO3 is observed at 1000 °C.