On calculations of basic structural parameters in multi-principal element alloys using small atomistic models

Multi-principal element alloys (MPEAs) are alloys that form solid solution phases and consist of three or more principal elements. Fundamental to the numerical study of mechanical properties of MPEAs are the calculations of their basic structural parameters such as lattice parameter and elastic constants. Due to the presence of multiple elements, calculation of each quantity should ideally consider multiple atomic configurations for each MPEA. However, direct calculations are sometimes expensive, and so some studies in the literature either considered only one atomic configuration or used an indirect method to provide an estimation. In this paper, we calculate the lattice parameters, cohesive energies, and elastic constants of 42 equal-molar refractory MPEAs using small atomistic models. For each quantity in each MPEA, four approaches are used: multiple direct calculations using the alloy potential, a single direct calculation using the A -atom potential, as well as estimations using two rules of mixtures. It is shown that the coefficient of variation based on the first approach positively scales with the lattice distortion of MPEAs. In addition, taking the mean values obtained via the first approach as references, we find that the other three approaches can overestimate or underestimate the basic structural parameters.