A novel ultrafine-grained Ni3Al with increased cyclic oxidation resistance

An ultrafine-grained (UFG) Ni3Al was fabricated by annealing an electrodeposited Ni–Al composite in vacuum at 600 °C for 2 h. The UFG Ni3Al, compared to a compositional-similar but coarse-grained (CG) alloy prepared by arc-melting, exhibited a greatly increased cyclic oxidation resistance at 900 °C. Microstructural investigation showed that the CG alloy grew a scale with a high susceptibility to buckling and cracking because of the formation of large voids at the scale/metal interface, but that the UFG alloy grew an adherent scale, because its typical structure prevented the formation of the interface void during oxidation.

Research highlights
► An ultrafine-grained Ni3Al with dispersions of ultrafine pores is developed.
► The UFG Ni3Al grew an adherent alumina scale during cyclic oxidation at 900 °C.
► The UFG structure helps to prevent large interface void formation during oxidation.
► Distribution of fine pores in UFG Ni3Al does not affect the alumina scale adhesion.
► Alumina scale on arc-melted Ni3Al spalled due to the large interface void formation.