Synthesis, characterization, and first-principles analysis of Mo2NiB2-type high-entropy boride ceramic

Abstract

A Mo2NiB2-type high-entropy boride ceramic with the nominal formula of (Mo0.5W0.5)2(Fe0.3Co0.35Ni0.35)B2 (abbreviated as X3B2) was synthesized by vacuum sintering. The phase structure, crystalline construction, bonding, and hardness properties were clarified in detail by first-principles calculations and experiment. The results show that the as-synthesized sample exhibits single phase and satisfied compositional homogeneity. Moreover, it can be obtained that both Mo–B bonds and W–B bonds in X3B2 exhibit the covalent characteristics, while the binding of Mo–B is stronger than the other. Initial property assessments show that the Vickers hardness of X3B2 is generally more than 20% higher than the reported Mo2NiB2. These results suggest an idea to achieve high hard and high-performance materials via exploring high-entropy ternary-boride ceramic.