Effect Of Y2O3 on microstructure and oxidation of γ-Ni+γ′-Ni3Al coatings transformed from electrodeposited Ni-Al films at 1 000 °C

The electrodeposited Y(2)O(3)-dispersed gamma-Ni+gamma'-Ni(3)Al coatings on Ni substrates were developed by the conversion of electrodeposited Ni-Al-Y(2)O(3) films with dispersed Al microparticles in Ni matrix into Ni(3)Al by vacuum annealing at 800 degrees C for 3 h. For comparison, Y(2)O3-free gamma-Ni+gamma'-Ni(3)Al 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(2)O(3)-dispersed gamma+gamma' coatings exhibit finer grains, a more homogeneous distribution of gamma', and a narrowed gamma' phase spacing compared with the electrodeposited Y(2)O(3)-free gamma+gamma' coatings. The oxidation at 1 000 degrees C shows that the addition of Y(2)O(3) significantly improves the oxidation resistance of the electrodeposited gamma+gamma'coatings. The effect of Y(2)O(3) particles on the microstructure and oxidation behavior of the electrodeposited gamma+gamma' coatings was discussed in detail.