Fine-grained dual-phase high-entropy ceramics derived from boro/carbothermal reduction

In the current work fine-grained dual-phase, high-entropy ceramics (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 )B 2 -(Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 )C with different phase ratios are prepared from powders synthesized via a boro/carbothermal reduction approach, by adjusting the content of B 4 C and C in the precursor powders. Phase compositions, densification, microstructure, and mechanical properties have been investigated. Due to the combination of pinning effect and the boro/carbothermal reduction approach, the average grain sizes (0.5–1.5 µm) of the dual-phase high-entropy ceramics, were much smaller as compared with previously reported values. The dual-phase high-entropy ceramics with 15 mol% boride phase exhibit the highest Vickers hardness (24.21 GPa) and fracture toughness (3.2 MPa•m 1/2 ).