ABSTRACT
Knowledge of the role of oxide dispersoids in ODS alloys during high-temperature oxidation in air is uncertain. The metal/oxide interface, across which matter must be transferred if oxidation is to continue, may be the preferred ‘sink’ for vacancies under all circumstances. Alternatively, the interfaces between dispersed oxide particles and the metallic matrix may provide favourable sites for vacancy annihilation, reduce the extent of condensation at the main metal/oxide interface and thereby improve the overall resistance to oxidation.
By comparing the oxidation behaviour of nickel, with and without oxide particles, it has been shown that the rate of oxidation for Ni-0.5Y2O3 samples is lower than that of commercially-pure Ni (99.9%). Metallographic evidence is provided to show that the coherent oxide scales formed on Ni-Y2O3 samples are associated with void formation at Y2O3 particles.
