The effect of N vacancy on the synthesis and properties of high-entropy nitride ceramics (Ti0.25V0.25Cr0.25Nb0.25)N0.825

Abstract

High-entropy ceramics (HECs) have gained significant attention in ceramics research due to their unique single-crystal structure, extensive composition range, and exceptional physicochemical properties. In this study, TiN_0.3 with anionic vacancies was prepared using mechanical alloying, while high-entropy nitride ceramics (Ti_0.25V_0.25Cr_0.25Nb_0.25)N_0.825 were synthesized using the Spark Plasma Sintering (SPS) process, utilizing TiN_0.3 as a sintering aid. The microstructure and mechanical properties of the high-entropy nitride ceramics at different sintering temperatures were thoroughly investigated. The results indicate that (1) non-stoichiometric TiN_0.3 was formed after 48 h of high-energy ball milling of Ti and TiN due to the concentration gradient, (2) single-phase Face-Centered Cubic (FCC) structured high-entropy nitride ceramics (Ti_0.25V_0.25Cr_0.25Nb_0.25)N_0.825 were synthesized using TiN_0.3 as a sintering accelerator, and (3) the maximum values of flexural strength (925 ± 46 MPa), hardness (16.88 ± 1.50 GPa), and fracture toughness (3.02 ± 0.15 MPa m^1/2) of the high-entropy nitride ceramics (Ti_0.25V_0.25Cr_0.25Nb_0.25)N_0.825 were achieved at a temperature of 1700 °C. This paper presents an innovative approach that combines vacancies with high-entropy ceramics, providing a novel synthetic pathway for high-entropy nitride ceramics. This new synthesis method opens up opportunities for exploring fresh directions in the research and application of ceramic materials, holding significant scientific importance and promising application prospects.