Preparation and Mechanical Properties of High-Entropy Ceramics (TiZrHfNbTa)C

We prepared dense high-entropy ceramic material (TiZrHfNbTa)C by hot pressing; the optimum hot-pressing temperature is 2000°C. At lower temperatures, zirconium oxides, hafnium oxides, and undissolved carbides were observed in the ceramic composition. The strength of the resulting ceramics at room temperature was 394 ± 72 MPa, at a temperature of 1600°С, it was 119 ± 31 MPa. For pure carbides, a significant drop in hardness was observed at an increased load on the indenter, while for (TiZrHfNbTa)C, hardness is retained under any load. To achieve the maximum hardness and strength of high-entropy ceramics (TiZrHfNbTa)C, the amount of ZrO2 and HfO2 in the composition of ceramics should be decreased with a simultaneous decrease in grain size by using submicrometer-scale powders and selecting proper technological modes of production.