Efficient first-principles methods of calculating stacking fault energies in high entropy alloys: comparison of FCC and BCC lattices

Due to their unusual structure and composition, high entropy alloys (HEAs) have favorable properties such as high service temperatures, strength, and ductility, making them potential candidates for high performance engineering material applications. In the present work, first-principles based calculations using density functional theory were used to analyze stacking fault energies in candidate BCC and FCC single-phase quinary HEA systems. Special quasi-random structures and the GGA-PBE exchange correlation functional were used. Two methods for making the calculations more efficient were employed: (i) a lower ordering averaging method based on a quinary HEAs constituent ternary systems, and (ii) the use of inferential statistics to calculate predictive error bars of the stacking fault energy using a small subset of atomic configurations. Intrinsic stacking faults in FCC CoCrFeMnNi on the {111} planes are investigated using the lower order averaging method. “Twinning-sense” and “non-twinning-sense” stacking faults on the (112) plane, with ABCDEFA stacking, were investigated in BCC AlNbTaTiV using the inferential statistics method. Results are compared to known literature where available, and the implications for using both methods for HEA database development are discussed.