High‐Strength ZrC Ceramics Doped with Aluminum

High‐strength ZrC ceramics with relative density above 98% were prepared by reactive hot pressing of ZrC and Al at 1900°C. The reaction between ZrC and Al resulted in the formation of ZrC 1− x , Zr 3 Al 3 C 5 and Zr – Al compound such as AlZr 3 and Al – C – Zr . The intermediate product AlZr 3 below 1600°C and remained Al – C – Zr phase could form liquid phase and promoted the first stage of densification process. The improvement in densification behavior at higher temperatures (1800°C–1900°C) could be attributed to the formation of nonstoichiometric ZrC 1− x . Adding 5 wt% and 7.5 wt% Al to ZrC , the formed ZrC 0.85 – Zr 3 Al 3 C 5 and ZrC 0.80 – Zr 3 Al 3 C 5 based ceramics had 3‐point bending strength as high as 757 ± 79 MPa and 967 ± 50 MPa, respectively, with hardness and fracture toughness being 16.2–18.3 GPa and 3.3–3.5 MPa m 1/2 , respectively.