Effect of grain size and grain growth on oxidation behaviour of ODS alloy MA760

Isothermal oxidation kinetics and post-oxidation SEM and X-ray analysis have been carried out for the nickel based Yttria dispersed alloy MA 760 in both as-extruded and annealed forms, which correspond to fine and coarse grained structure respectively. The oxidation temperature are 1200 degree centigrade and 1100 degree centigrade respectively, which for the as-extruded material represent conditions with and without significant grain growth during oxidation. grain size and grain growth has been found to have adverse effect on oxidation resistance. The possible mechanisms responsible for the effects of grain size and grain growth are discussed. (author)