Characterization of oxidation mechanisms in a family of polycrystalline chromia-forming nickel-base superalloys

The oxidation properties of a family novel polycrystalline Ni-based superalloys with varying Ti:Nb ratio have been studied, which has shown correlation between increasing titanium content and accelerated kinetics. High-resolution characterization microstructure chemistry was carried out on the resultant oxide layers using SEM/EDX Atom Probe Tomography to precisely locate Ti segregation within chromia scales, in order identify potential mechanism explain this correlation. Despite some spread data, levels dissolved scales showed little nominal concentration or each alloy, indicating that rates are not reliant dopant bulk chromia. A number grain boundaries scale were targeted for APT analysis, as these known act short-circuit diffusion paths. Segregation Ti, Nb Ta observed, suggesting ion transport may instead be mediated by dopants present at rather than bulk.