Oxidation Mechanisms of (FeCr2V)92%W8% Medium Entropy Alloy for Nuclear Application: Insight from Ab Initio study

The 8 atom % W doping in FeCr₂V-based refractory medium-entropy alloy (RMEA) offers a cost-effective solution for structural materials in nuclear reactors due to its resistance to oxidation and superior mechanical properties. In this work, a synergy of DFT calculation and ab initio molecular dynamics was employed to investigate the dissociation, adsorption, and diffusion mechanism of oxygen on the surface of the optimized (FeCr₂V)_92%W_8% RMEA at various temperatures. The results confirmed the adsorption and dissociation of O₂ molecules on the alloy surface. At 300 K, projected density of states (PDOS) analysis revealed significant hybridization between Cr-d and Fe-d orbitals with O-p orbitals. At an elevated temperature of 1023 K, the hybridization between Cr and W with O remained strong, indicating the sustained formation of a stable protective oxide layer. Notably, tungsten contributed to the formation of a protective WO₃ oxide layer, enhancing the alloy’s oxidation resistance. Barrier energy calculations further revealed that W doping inhibits oxygen diffusion into sublayers, providing an effective oxidation resistance mechanism. These findings offer valuable insights into the oxidation resistance of RMEAs and their suitability as structural materials for high-temperature and radiation-intensive environments.