Influence of molten-salt-synthesised high-entropy (V0.2Cr0.2Mo0.2W0.2Ni0.2)B powder characteristics on superhard mechanism during spark plasma sintering

High-entropy monoborides (HEMBs) are promising materials for use in cutting tools and wear-resistant coatings owing to their super hardness. Because of the scarcity of reports on powder synthesis , extensive application of HEMBs is limited. To address this problem, a molten-salt-assisted strategy for synthesising HEMB powders is proposed herein. High-entropy (V 0.2 Cr 0.2 Mo 0.2 W 0.2 Ni 0.2 )B powders with CrB-type orthogonal crystal structures were successfully synthesised at 1500 °C and examined by using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy . Subsequently, the mechanism of powder synthesis using molten salt and the advantages of powders prepared by employing molten salt for the densification and hardness enhancement of ceramics were comprehensively evaluated. The (V 0.2 Cr 0.2 Mo 0.2 W 0.2 Ni 0.2 )B powders were densified by applying spark plasma sintering to study the microstructural evolution of bulk ceramics with a super hardness of 42.19 ± 2.66 GPa. This work has expanded the family of superhard HEMBs and provides a strong support for the further application of HEMBs.