An integrated experimental and Ab initio study on irradiation resistance and mechanical properties of FeCr2V-based refractory medium entropy alloys

Abstract

High Entropy Alloys (HEAs) and Medium Entropy Alloys (MEAs) stand out as promising structural materials for the next generation of fission and fusion reactors. In this work, we combined first principles modelling with experimental analysis to design a novel FeCr₂V-based Refractory Medium Entropy Alloys (RMEA) by doping it with tungsten. The impact of tungsten doping on irradiation resistance and the balanced mechanical properties of this novel alloy were investigated. The Density Functional Theory (DFT) results show that the RMEA can only form a stable solid solution with a concentration of W below 12 at. %. Introducing tungsten to the base material significantly improved the alloy’s mechanical properties, including bulk modulus, shear modulus, hardness, and irradiation resistance. These findings align well with our experimental results, providing strong supporting evidence for the accuracy and reliability of our theoretical predictions. Furthermore, the calculated vacancy formation energy demonstrates a significant strengthening in the material’s resistance against radiation-induced damage upon the inclusion of tungsten in the base material. The results of electronic properties show that there is a notable increase in electron accumulations as the tungsten content rises, which leads to more covalent bonding properties. By attaining a delicate equilibrium between metallic and covalent bonding, alloys can showcase an exclusive combination of high ductility, strength, and irradiation resistance as shown in the case of (FeCr₂V)_92%W_8%. This work provides an in-depth understanding of the design and optimization of this alloy, which contributes to the development of new structural material for nuclear application.