Effect of Y2O3 on microstructure and oxidation of -Ni+ ′-Ni3Al coatings transformed from electrodepositedNi-Al films at 1 000 ℃
(College of Materials Science and Engineering, Heilongjiang Institute of Science and Technology,Harbin 150027, China)
Abstract: The electrodeposited Y2O3-dispersed -Ni+ -Ni3Al coatings on Ni substrates were developed by the conversion of electrodeposited Ni-Al-Y2O3 films with dispersed Al microparticles in Ni matrix into Ni3Al by vacuum annealing at 800 ℃ for 3 h. For comparison, Y2O3-free -Ni+ ′-Ni3Al 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 Y2O3-dispersed + ′ coatings exhibit finer grains, a more homogeneous distribution of ′, and a narrowed ′ phase spacing compared with the electrodeposited Y2O3-free + ′ coatings. The oxidation at 1 000 ℃ shows that the addition of Y2O3 significantly improves the oxidation resistance of the electrodeposited + ′coatings. The effect of Y2O3 particles on the microstructure and oxidation behavior of the electrodeposited + ′ coatings was discussed in detail.
Key words: electrodeposition; -Ni+′-Ni3Al coatings; vacuum annealing; oxidation