High entropy alloys

Metallurgy

Materials science

Carbide

Ceramic

Pressing

Relative density

Grain size

Alloy

Microstructure

Quinary

Composite material

Carbothermic reaction

Hot pressing

Journal of Material Science and Technology

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 °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 °C for 1 h and 2100 °C for 0.5 h, respectively. The high-entropy ceramic exhibits a fine grain size of about 8.8 μm, 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.

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