Core Effect of Local Atomic Configuration and Design Principles of Al xCoCrFeNi 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 Al_xCoCrFeNi 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.