Rapid Experimental Screening of High-Entropy Diborides for Superior Oxidation Resistance

Due to the huge composition space, composition screening is of great importance to the optimization of high-entropy diborides (HEBs) with exceptional oxidation resistance. However, related studies are lacking. Here, a novel rapid, effective strategy to fully screen the compositions on the oxidation resistance of HEBs is proposed. Specifically, the synthesis of the equiatomic 1- to 9-cation multicomponent diborides of the IVB, VB, and VIB groups in seconds via an ultrafast ultrahigh-temperature synthesis technique is realized. Subsequently, combined with the thermogravimetric analysis and first-principles calculations, the roles of incorporated elements are systematically explored. The results show that Zr, Cr, Ta, Nb, and W elements are the key to the improved oxidation resistance of HEBs, while Ti, Mo, and V elements are destructive. In particular, the positive roles of metal elements are mainly attributed to the partial dissolution of the generated metal oxides into the generated B₂O₃ glass, which can improve the viscosity of B₂O₃ and thus enhance its high-temperature stability and reduce the oxygen diffusion rate, as confirmed by the first-principles calculations. This study paves a way to rapidly screen the elements in HEBs, which can be a guide for further anti-oxidation designs.