Predicting Single-Phase Synthesizability of Hexagonal High-Entropy Borides

High-entropy materials consisting of five or more elements can be stabilized by configurational entropy and exhibit superior physical and chemical properties for a wide range of potential applications. However, the vast phase space of possible elemental combinations poses challenges for a comprehensive exploration of stable high-entropy materials. Here, we employ the entropy forming ability (EFA) descriptor to systematically study high-entropy borides (HEBs) in the AlB2 hexagonal structure. First-principles density functional theory is utilized to compute the EFA values for 128 different five-metal HEBs composed of group 4-6 transition metals. The EFA results achieve good agreement with our experimental synthesis and x-ray diffraction data for selected low- and high-EFA compounds. The calculation thereby provides the feasibility prediction for synthesizing single-phase HEBs. Our study also demonstrates that EFA is an overall efficient and reliable descriptor for predicting the synthesizability of high-entropy materials.