High-temperature flexural strength of (TiZrNbTaCr)C high-entropy carbide ceramics: The double-edged effects of Cr carbide

The high-temperature flexural strength of the (TiZrNbTaCr)C ceramics with different Cr content is tested at 1200°C, 1400°C and 1600°C. Results indicate that Cr addition is beneficial to the strength by modifying microstructures, refining grain size and purifying grain boundary impurities, leading to the increase of flexural strength from 220 ± 27 MPa to 294 ± 47 MPa at 1200°C. On the other hand, adding Cr element introduces Cr carbides with low melting point which segregate at grain boundaries, and are detrimental to strength at high temperature. As a result, the fracture mode is predominantly intergranular at elevated temperature and the flexural strength decreases with increasing temperature.