High-temperature oxidation of Fe3Al containing yttrium

The effect of yttrium addition on the oxidation behavior of Fe₃Al alloys was investigated in terms of oxidation rate and oxide adhesion in the temperature range of 800 to 1100 °C. The oxidation rate of the alloys, Fe-14.3 wt% Al and Fe-14.1 wt% Al-0.3 wt% Y, was nearly identical, and the parabolic rate constant as a function of temperature is found to be K _p = 5128 exp–39506 (cal/mol)/RT] mg²/cm⁴ hr. While the alumina scale formed on the Y-free Fe₃Al alloy was observed to be fragile and spalled easily, the oxide layer formed on the Fe₃Al-Y was protective, dense, and adhesive. Based on the microstructural, morphological, and compositional studies, the adhesion improvement due to the yttrium addition was discussed in terms of growth stress, the formation of pegs and scale growth mechanism.