First-principle calculation investigation of NbMoTaW based refractory high entropy alloys

Alloying is an effective method to strengthen high entropy alloys (HEAs). Unfortunately, most of the investigations focus on the perspective of experiments and few are available from the perspective of atomic and electrical scale such as electronic structure, energy band structure and charge density. In present work, first-principle calculation based on density functional theory was employed to calculate the ground state total energy, lattice parameters, elastic constants and polycrystal modulus of NbMoTaW and NbMoTaWV refractory high entropy alloys (RHEAs). The effects of V addition on the phase structure, elastic properties and electronic structure of NbMoTaW-based RHEAs were studied, respectively. V addition is helpful to improve the mechanical properties of NbMoTaW alloy according to the calculated value of shear modulus to bulk modulus, Cauchy pressure and Vickers hardness. Based on calculated energy band, electronic state density, charge density and charge density difference, V addition is found to shorten the pseudo-energy gap and enhance interaction force between Mo and W atoms. This tends to improve the mechanical properties of the alloy. The calculated results were in good agreement with the experimental data, demonstrating that the methods were effective in predicting the performance of RHEAs.