Oscillatory pressure sintering of high entropy (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 ceramic

Highly pure and dense high entropy (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 ceramics have been obtained via oscillatory pressure sintering (OPS) at 1800 °C–1900 °C for 1 h under 30 ± 5 MPa. The formation of a single-phase solid solution was confirmed through XRD and TEM. The relative density and hardness of (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 sintered at 1900 °C are 96.6% and 24.0 ± 1.0 GPa, respectively. The thermal conductivity of (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 is 12.2 W/m·K at 30 °C, which is only 10% of ZrB2, which might greatly be related to mass fluctuations and strain filed fluctuations caused by the interaction of solid solution effects. This is the first report of preparation of high entropy ceramics using oscillatory pressure sintering.