Diffusion-controlled growth and microstructural evolution of aluminide coatings

Abstract

The diffusion-controlled growth and microstructural evolution at the interface of aluminide coatings and different substrates such as Ni-base superalloys and steel are reviewed. Quantitative diffusion analysis indicates that the diffusion rates of components in the beta-NiAl phase increases with the addition of Pt. This directly reflects on the growth rate of the interdiffusion zone. The thickness and formation of precipitates between the bond coat and the superalloys increase significantly with the Pt addition. Mainly Fe2Al5 phase grows during hot dip aluminization of steel along with few other phases with very thin layer. Chemical vapor deposition process is being established for a better control of the composition of the Fe-aluminide coating on steel.