The Ni-Al-Hf Multiphase Diffusion

Abstract

The generalized Darken method was applied to simulate the diffusion between γ-Ni| γ'-Ni3Al and γ'-Ni3Al|β-NiAl interfaces. The results of calculations were compared with the experimental concentration's profiles of nickel, aluminum and hafnium in aluminide and hafnium doped aluminide coatings deposited by the CVD and PVD methods on pure nickel. The method deals with the Wagner's integral diffusion coefficients and thermodynamic data -activities of components. The experimental results agree with the simulated ones.

SEM/TEM Investigation of Aluminide Coating Co-Doped with Pt and Hf Deposited on Inconel 625

“…Its location in this area could be explained by scavenging by surplus hafnium of any oxide remnants present during the CVD deposition process. Such surplus is a direct consequence of fast saturation of the coating with hafnium and its low diffusivity in the β-NiAl type phase [ 24 ].…”