First-Principles Calculations of Stacking Fault Energies in Quinary High-Entropy Alloy Systems

High entropy alloys (HEAs) are composed of equal or nearly equal quantities of five or more metals that solidify into a single, or sometimes dual, solid solution phase. Due to improved properties in high-temperature and high-stress applications, HEAs have the potential to replace traditional alloy systems in future engineering applications, such as turbine blades and thermal spray coatings. In the present work, first-principle calculations based on density functional theory are used to calculate and rank the stacking fault energies of several quinary HEA systems in order to better understand the slip and deformation behavior of HEA systems. Special quasirandom structures are used to represent the single solid solution with a finite number of atoms and calculations are performed in the Vienna ab initio simulation package within the generalized gradient approximation as implemented by Perdew, Burke, and Ernzerhof. Stacking fault energy calculations are based on the difference between the ground state energy of the perfect HEA structure and the ground state energy of a faulted HEA structure. To validate the calculations, results are compared to experimental data, such as lattice parameter and formation energy, for well-studied HEA system.