Abstract: High entropy carbide ceramics (HECC) are solid solution of inorganic compounds with five or more principal metal cations. Research interests in HECC are dramatically sparked by the enormous possibilities in composition-microstructure-property tailoring. As widely acknowledged, HECCs enjoy higher hardness and oxidation/corrosion/wear resistance, as well as lower thermal conductivity than conventional engineering carbide ceramics, making them the most potential candidates for state-of-the-art structural and functional applications in extreme service conditions. Despite the advantages, however, the poor densification coupled with low fracture toughness significantly limited the practical applications of HECC. Adding to the difficulty, the literature available for toughening HECC is woefully limited. In consideration of this insufficiency, we apply towards offer a comprehensive, critical review of the mechanical behavior of HECC, highlighting the densification enhancing strategies (carbon content, sintering techniques, grain size, sintering aids, etc.) as well as toughening methods including particle toughening, whisker/fiber toughening, synergistic toughening, graphene-carbon nanotube toughening, to further the service reliability of HECC in practical industrial applications. Furthermore, despite some significant successes, important directions for further development of HECC are given as multi-dimensional gradient HECC, additive manufacturing of HECC, processing-composition-microstructure-property relationship prediction and genomes of HECC based on machine learning, and high-throughput computing, etc.

Key words: High entropy carbide ceramic, Densification, Toughening, Mechanical properties