High-entropy carbonitride (Hf,Ta,Nb,Zr)(C,N): One step mechanically induced self-sustaining reaction and spark plasma sintering

High-entropy (Hf,Ta,Nb,Zr)(C,N) carbonitride powder was synthesized by mechanically induced self-sustaining reaction (MSR) in a high-energy mechanical processing (HEBM) process in a planetary ball mill. HEBM contributed to the formation of layered composite particles and initiation of the combustion reaction. The completeness of the reaction inside the jars was observed after 30 min of HEBM, while the powder of the reaction product consisted of agglomerates of rounded particles ranging in size from 20 to 600 nm. The effect of spark plasma sintering temperature on the relative density of ceramics has been studied, and it has been shown that sintering at 2000 °C makes it possible to obtain dense ceramics (> 98%). Bulk high-entropy carbonitride (Hf,Ta,Nb,Zr)(C,N) demonstrated high values of nanohardness 30.1 GPa and indentation fracture resistance 4.2 MPa∙m1/2, as well as compressive strength at room temperature 3005 MPa.