Low-temperature densification of high-entropy (Ti,Zr,Nb,Ta,Mo)C-Co composites with high hardness and high toughness

In order to prepare high toughness (Ti,Zr,Nb,Ta,Mo)C ceramics at low temperatures while maintaining high hardness, a liquid-phase sintering process combined with Co-based liquid-phase extrusion strategy was adopted in this study. The densification temperature can be lowered to 1350 degrees C, which is much lower than the solid-state sintering temperature (similar to 2000 degrees C) generally employed for high-entropy carbide ceramics. When sintered at 1550 degrees C and 30 MPa applied pressure, part of the Co-based liquid-phase was squeezed out of the graphite mold, such that only similar to 3.21 vol% of Co remained in the high-entropy ceramic. Compared to the Co-free solid-state sintered (Ti,Zr,Nb,Ta,Mo)C ceramics, prepared at 2000 degrees C and 35 MPa, the hardness was slightly decreased from 25.06 +/- 0.32 to 24.11 +/- 0.75 GPa, but the toughness was increased from 2.25 +/- 0.22 to 4.07 +/- 0.13 MPa center dot m(1/2). This work provides a new strategy for low-temperature densification of high-entropy carbides with both high hardness and high toughness.

Automated summary

This study successfully prepared (Ti,Zr,Nb,Ta,Mo)C ceramics with high hardness and high toughness using a liquid-phase sintering process combined with a Co-based liquid-phase extrusion strategy. The densification temperature was significantly reduced to 1350 degrees C, and part of the Co-based liquid-phase was removed during the sintering, resulting in a lower Co content in the ceramic.