Fabrication and properties of (Zr_0.2Ti_0.2Ta_0.2Nb_0.2Cr_0.2)B₂ high-entropy ceramic by hot-press sintering

The five-component high-entropy boride ceramic (Zr_0.2Ti_0.2Ta_0.2Nb_0.2Cr_0.2)B₂ is successfully prepared via hot-press sintering at 1800 ℃. A systematic investigation is conducted on its phase composition, microstructure, mechanical properties and high-temperature stability. The results show that the ceramic primarily consists of a single high-entropy phase, with minor localized enrichments of Zr and Ta. The Vickers hardness and three-point flexural strength reach 19.03 GPa and 279.76 MPa, respectively, with the fracture surface exhibiting typical brittle transgranular fracture characteristics. After heat treatment at 1500 ℃ for 50 h, the microstructure of the high-entropy ceramic remains stable, showing no grain growth or precipitation of new phases. Neither hardness nor strength undergos significant changes, demonstrating excellent high-temperature structural stability and retention of mechanical properties.