OXIDATION OF ODS ALLOYS

NiCr, NiCrAl and FeCrAl based Oxide Dispersion Strengthened (ODS) high temperature alloys possess far better oxidation resistance than dispersion free alloys of the same base composition. The presence of yttria dispersions leads to excellent scale adherence and a very selective oxidation of the scale forming element. Most of the observed differences in microstructure and protective properties between oxide scales on ODS and non-ODS alloys can be explained by differences in scale transport mechanisms. Although other dispersions have been found to have a positive effect on oxidation behaviour similar to that of yttria, they seem to possess no major advantage, provided that the yttria content is properly adjusted to the actual alloy system.