OXIDATION OF BETA-FEAL AND FE-AL ALLOYS

The oxidation kinetics of the intermetallic phase beta-FeAl has been i nvestigated by means of thermogravimetry in the temperature range 800- 1100 degrees C. At temperatures higher than 900 degrees C the initiall y formed metastable aluminium oxides are converted to adherent and slo w growing alpha-Al2O3 scales. The rate of conversion accelerates with increasing temperature. The parabolic rate constants kp are comparable with those of beta-NiAl. The influence of the Al content on the oxida tion behaviour was investigated in exposure experiments at low oxygen partial pressures for samples with 5 to 48 at.% Al. The oxide morpholo gy changes only with the oxidation temperature, neither variations in Al content nor in O-2-pressure has any influence, In samples with high er Al content cavities are formed beneath the oxide scale in the metal lic matrix.