Low‐temperature sintering of single‐phase, high‐entropy carbide ceramics

TLDR

The authors synthesized (Hf, Zr, Ti, Ta, Nb)C high‑entropy ceramic powders by high‑energy ball milling and carbothermal reduction at 1600 °C, then hot‑pressed them to produce dense, rock‑salt phase ceramics. Hot‑pressing from 1750 °C to 1900 °C increased relative density from 95 % to 99.3 % and produced phase‑pure, 0.6–1.2 µm grain ceramics, marking the first demonstration of low‑temperature densification and fine microstructure in high‑entropy carbides.

Abstract

Abstract Dense (Hf, Zr, Ti, Ta, Nb)C high‐entropy ceramics were produced by hot pressing (HP) of carbide powders synthesized by carbothermal reduction (CTR). The relative density increased from 95% to 99.3% as the HP temperature increased from 1750°C to 1900°C. Nominally phase pure ceramics with the rock salt structure had grain sizes ranging from 0.6 µm to 1.2 µm. The mixed carbide powders were synthesized by high‐energy ball milling (HEBM) followed by CTR at 1600°C, which resulted in an average particle size of ~100 nm and an oxygen content of 0.8 wt%. Low sintering temperature, high relative densities, and fine grain sizes were achieved through the use of synthesized powders. These are the first reported results for low‐temperature densification and fine microstructure of high‐entropy carbide ceramics.