Computational insights into the corrosion behavior of NbTaMoW and NbTaMoWV high-entropy alloys in molten fluoride salts

Abstract

Molten salt reactors (MSRs) expose structural materials to harsh conditions, such as elevated temperatures, corrosive fluoride salts, and substantial neutron irradiation. These factors contribute to intricate degradation processes, including radiation-induced defect development, void swelling, and corrosion. Refractory high-entropy alloys with a body-centered cubic structure provide noteworthy thermal stability and mechanical strength, making them excellent candidates for MSR application. This study explores the corrosion properties of NbTaMoW and NbTaMoWV in FLiBe molten salt via density functional theory and ab initio molecular dynamics simulations. Analyses of electronic structure, including density of states and crystal orbital Hamilton population, shed light on interfacial bonding and charge distribution. NbTaMoW shows minimal d-band shifts and weak fluorine interaction, indicating enhanced oxidation resistance. Adding vanadium to form NbTaMoWV further diminishes oxidative vulnerability and stabilizes the electronic structure at the salt interface, suggesting superior corrosion resistance in molten salt conditions.