Microstructure and characterization of (Ti,V,Nb,Ta)(C,N) high-entropy ceramic

(Ti0.25V0.25Nb0.25Ta0.25)(C1-xNx) high-entropy ceramics with various N contents (x = 0, 0.1, 0.2, 0.3) were successfully produced by spark plasma sintering to investigate the influence of N element on their microstructure and properties. The mixed carbide and nitride powders were sintered to form a single-phase face-centered cubic structure ceramic with a uniform composition at 2100 degrees C for 10 min. The introduction of slight nitrides in high-entropy ceramics refined the grain size and enhanced the hardness of ceramics. The (Ti0.25V0.25Nb0.25Ta0.25) (C0.8N0.2) ceramic demonstrated a fine grain size of 5.29 mu m, a high relative density of 96.7% and an excellent hardness values of 20.6 GPa at 9.8 N and 29.3 GPa at 50 mN. With increasing contents of nitrides, the wear resistance and thermal conductivity of high-entropy ceramics increased firstly and then decreased. The ceramic with 30 at.% nitrides showed a relatively low thermal conductivity of 11.27 W m(-1) K-1 at room temperature. The high-entropy carbonitride ceramics had a potential application in high temperature structure parts and machining tools.

Automated summary

The high-entropy ceramics were successfully produced by spark plasma sintering with varying N contents to investigate the impact of N element on microstructure and properties. The introduction of slight nitrides refined the grain size and enhanced hardness. The wear resistance and thermal conductivity initially increased with greater nitride content before decreasing.