Effect of an oxide dispersion on the critical Al content in Fe-Al alloys

Oxide-dispersed iron aluminides with Al contents ranging from 10 to 28 at.% were oxidized in air at temperatures between 600 and 1300 °C in order to determine the critical Al content necessary to form a protective, external alumina scale. A Y₂O₃-Al₂O₃ dispersion, performed similarly to an Al₂O₃ dispersion, indicated little effect of Y on the critical Al content. Compared to ingot-processed iron aluminides, the addition of an oxide dispersion reduced the critical Al content at 900 °C. This reduction is attributed to the finer grain size in the oxide-dispersed Fe-Al.