Zirconium influence on microstructure of aluminide coatings deposited on nickel substrate by CVD method

Abstract

Influence of Zr on the microstructure and phase characteristics of aluminide diffusion coatings deposited on the nickel substrate has been investigated in this study. The coatings with and without zirconium were deposited by CVD method. The cross-section chemical composition investigations revealed that during the coatings formation, there is an inward aluminum diffusion and outward nickel diffusion in both types of coatings (with and without zirconium), whereas zirconium is located far below the coating surface, at a depth of ~17 μm, between β-NiAl phase and γ ′-Ni3Al phase. XRD examinations showed that β-NiAl, γ-NiAl and γ ′-Ni 3Al were the main components of the deposited coatings. β-NiAl phase is on the surface of the coatings, whereas γ-NiAl and γ ′-Ni3Al form deeper parts of the coatings. Zirconium is dissolved in NiAl on the border between β-NiAl and γ ′-Ni3Al.