Microstructure and Positron Lifetimes of Aluminide Coatings on Inconel 713

Abstract

The microstructure of the palladium modified and non-modified aluminide coatings was examined by the EDS and the positron annihilation spectroscopy methods. Both coatings have a double layer structure: β-NiAl phase or β-(Ni,Pd)Al phase on the top and the interdiffusion zones with the chromium and molybdenum rich phases in the β-NiAl or or β-(Ni,Pd)Al phase below. Palladium, that forms the β-(Ni,Pd)Al phase and substitutes for nickel atoms causes the increase of the positron lifetime value due to the increase in the number of open volume defects in the lattice which are jogs or vacancies on dislocation lines.