The effect of internal stable nitride and oxide dispersion on the high temperature oxidation of Fe [sbnd]Cr alloys

Abstract

The behaviour of Fe Cr alloys containing either a dispersed nitride or oxide phase is examined. Fe-12, 14 or 18% Cr containing 0.5 or 1 wt% Ti were used. The oxide dispersion was introduced by an internal oxidation treatment using a 50/50 Cr/Cr 2O 3 mixture in a sealed quartz capsule at 1100 or 1200°C. Internal nitrides were produced by nitridation in either an 80/20 or a 90/10 H 2/N 2 mixture at 1150°C. Subsequent oxidation tests of the treated alloys were carried out isothermally at 900, 1000 and 1100°C, or by thermal cycling (3 h cycles) at 1100°C. The dispersed nitride phase is not as effective in improving the oxidation resistance as corresponding dispersed oxides. Considerable particle coarsening is observed and the nitrides tend to dissociate and are converted to oxide near to the alloy/scale interface.