Microstructure, Mechanical and Tribological Properties of High-Entropy Carbide (MoNbTaTiV)C5.

ABSTRACT

High-entropy carbide (NbTaTiV)C4 (HEC4), (MoNbTaTiV)C5 (HEC5), and (MoNbTaTiV)C5-SiC (HEC5S) multiphase ceramics were prepared by spark plasma sintering (SPS) at 1900 to 2100 °C, using metal carbide and silicon carbide (SiC) as raw materials. Their microstructure, and mechanical and tribological properties were investigated. The results showed that the (MoNbTaTiV)C5 synthesized at 1900-2100 °C had a face-centered cubic structure and density higher than 95.6%. The increase in sintering temperature was conducive to the promotion of densification, growth of grains, and diffusion of metal elements. The introduction of SiC helped to promote densification but weakened the strength of the grain boundaries. The average specific wear rates for HEC4 were within an order of magnitude of 10-5 mm3/N·m, and for HEC5 and HEC5S were within a range of 10-7 to 10-6 mm3/N·m. The wear mechanism of HEC4 was abrasion, while that of HEC5 and HEC5S was mainly oxidation wear.