Effect of Y 2O 3 on microstructure and oxidation of γ -Ni+γ′ -Ni 3Al coatings transformed from electrodeposited Ni-Al films at 1 000 °C

Abstract

The electrodeposited Y 2O 3-dispersed γ-Ni+γ ′-Ni 3Al coatings on Ni substrates were developed by the conversion of electrodeposited Ni-Al-Y 2O 3 films with dispersed Al microparticles in Ni matrix into Ni 3Al by vacuum annealing at 800 °C for 3 h. For comparison, Y 2O 3-free γ-Ni+γ ′-Ni 3Al coatings with a similar Al content were also prepared by vacuum annealing the electrodeposited microparticle-dispersed composite coatings of Ni-Al under the same condition. SEM and TEM characterizations show that the electrodeposited Y 2O 3-dispersed γ+γ ′ coatings exhibit finer grains, a more homogeneous distribution of γ ′, and a narrowed γ ′ phase spacing compared with the electrodeposited Y 2O 3-free γ+γ ′ coatings. The oxidation at 1 000 °C shows that the addition of Y 2O 3 significantly improves the oxidation resistance of the electrodeposited γ+γ ′coatings. The effect of Y 2O 3 particles on the microstructure and oxidation behavior of the electrodeposited γ+γ ′ coatings was discussed in detail.