Microstructure and mechanical properties of (TiZrNbTaMo)C high-entropy ceramic

A high-entropy (TiZrNbTaMo)C ceramic has been successfully fabricated by hot pressing the newly-synthesized quinary carbide powder to investigate its microstructure and mechanical properties. The carbothermal reduction process of equimolar quinary metallic oxides at 1500 degrees C for 1 h generates a carbide powder mixture, which consists mainly of TaC- and ZrC-based solid solutions. The as-synthesized powder was then sintered to form a single-phase high-entropy ceramic by a two-step hot pressing at 1850 degrees C for 1 h and 2100 degrees C for 0.5 h, respectively. The high-entropy ceramic exhibits a fine grain size of about 8.8 pina, a high compositional uniformity and a high relative density of 98.6% by adding Mo as the strategic main component. The measured nanohardness values of (TiZrNbTaMo)C ceramic are 25.3 GPa at 9.8 N and 31.3 GPa at 100 mN, respectively, which are clearly higher than those of other available high-entropy carbide ceramics. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.