| Abstract Scope |
To date, RHEAs have been limited by their corrosion behavior. Major factors controlling oxidation and/or corrosion resistance of traditional alloys are the properties of the passive films that form on the exposed surfaces. Traditional corrosion-resistant alloys can spontaneously form stable, protective films upon environmental exposure. The compositional complexity that makes HEAs interesting from a mechanical standpoint also makes their oxidation / corrosion resistance difficult. Each lattice site in HEAs can be randomly dispersed by any element, depending on its concentration, causing the local atomic environment to vary from one lattice site to the next. In RHEAs, Al, Cr, or Si may be negatively influenced by divergent migration/diffusion rates with other RHEAs elements, partitioning tendencies, and clustering affinities.
The fundamental thermochemistry of HEAs needs to be understood, and the thermokinetic parameters must be carefully characterized to enable the prediction of preferred surface chemistries that promote passivity. |