Enhancing hardness-toughness synergy through entropy gain effects: Implications for ceramic cutting tool materials

Comparable to traditional ceramics, high-entropy ceramics (HECs) possess outstanding hardness, wear resistance, and thermal stability. Nonetheless, their application, especially within the cutting tools industry, is constrained by low fracture toughness. Addressing the brittleness and enhancing fracture toughness are pivotal for the practical deployment of HECs. This study employs Density Functional Theory (DFT) calculations to comprehensively analyze the crystalline, mechanical, electronic, and thermodynamic properties of (Ti, Ta, Nb, Zr, V)(C,N) and synthesizes high-toughness carbonitride ceramics through SPS. Findings reveal that the incorporation of C and N anions significantly augments the configurational entropy of (Ti, Ta, Nb, Zr, V)(C,N) ceramics, thereby mitigating the necessity for elevated sintering temperatures. Ceramics fabricated under conditions of 1600 ? sintering temperature, 10 min holding time, and 30 MPa sintering pressure exhibited superior mechanical performance, with a hardness of 22.24 GPa, fracture toughness of 10.67 MPa·m1/2, and flexural strength of 1296 MPa. These results underscore the potential of (Ti, Ta, Nb, Zr, V)(C,N) as a candidate for high-performance cutting tool materials.