Enhanced hardness and toughness in (V, Zr, Nb, Ta)C high‐entropy ceramics via core‐rim structure

Abstract High‐entropy ceramics (HECs) have attracted widespread attention due to their broad application potential; however, their relatively low fracture toughness remains a critical challenge for practical implementation. In this study, the microstructure was tailored by exploiting the short‐range ordering and long‐range disorder characteristics, and (V, Zr, Nb, Ta)C‐based HECs with a novel internal Core‐rim structure were fabricated using spark plasma sintering. Subsequently, first‐principles density functional theory (DFT) calculations were employed to investigate the properties of the synthesized (V, Zr, Nb, Ta)C. The results indicated that, compared with HECs exhibiting a single‐phase microstructure, the introduction of the Core‐rim structure into (V, Zr, Nb, Ta)C effectively improved fracture toughness without sacrificing hardness. Indentation testing revealed mechanical properties of 21.1 GPa in hardness and 8.3 MPa·m 1/2 in fracture toughness. These findings demonstrate that microstructural design strategies enabling self‐toughening in brittle and hard ceramics provide a promising pathway for the development of HECs combining both high hardness and high toughness.