Structure and mechanical properties of high-entropy carbide (Ti0.2Zr0.2Nb0.2Ta0.2Cr0.2)C: Effect of sintering method

High-entropy carbide ceramics (HECCs) have attracted increasing attention for extreme-environmental applications due to their unique multi-elemental compositions and outstanding mechanical properties. While most existing studies focus on IVB and VB transition metals synthesized via spark plasma sintering (SPS), group VIB elements, such as Cr, have been comparatively less studied. In this study, a Cr-containing HECC, (Ti0.2Zr0.2Nb0.2Ta0.2Cr0.2)C, was synthesized via both high temperature and high pressure (HTHP) sintering and SPS. Comparative analysis revealed that HTHP processing at 5 GPa and 1600 °C produced ultrafine grains (∼0.41 μm), moderate density (94.2%), and enhanced fracture toughness (5.05 ± 0.37 MPa m1/2). In contrast, SPS at 1800 °C yielded near-theoretical density (99.4%) and higher nanohardness (34.15 ± 0.51 GPa) but resulted in significant grain coarsening (∼6.24 μm) and reduced fracture toughness (∼3.5 MPa m1/2). These findings highlight the distinct structure–property relationships governed by the sintering route and provide insights into tailoring HECC performance for demanding service conditions.