Core Effect of Local Atomic Configuration and Design Principles of Al x CoCrFeNi High-Entropy Alloys

High-entropy alloys (HEAs) are known to have four core effects that lead to the superior mechanical properties over traditional alloys. In this paper, we investigated a new core effect that contribute to the unique characteristics of HEAs. The stacking fault and twin formation energies of AlxCoCrFeNi HEAs were calculated with the density functional theory (DFT) methods, which show large variations and even negative energies due to the new core effect. A design principle was proposed to predict the mechanical properties of the HEAs. The effect of temperature was also determined, which is consistent with the experimental results.