Nanoparticles in zirconium-doped aluminide coatings

The microstructure of the zirconium doped aluminide coating deposited on the nickel substrate by the CVD method is presented. TEM analysis proved that the ß-NiAl and the γ′-Ni3Al are the main phases of the deposited coating. Some dislocations in the nickel substrate and in the coating were observed. The cross section chemical composition examination revealed, that the coating was formed via the inward aluminum diffusion and the outward nickel diffusion. SEM analysis revealed small zirconium content (0.2–0.4 at%) on the cross-section of the aluminide coating. Such zirconium content leads to zirconium dissolution in the aluminide coating. Long time of zirconizing (4 h) caused the appearance of zirconium nano particles at the surface of the coating. TEM investigations confirmed that zirconium formed inclusions on the coating’s surface.