High toughness in pressureless densified ZrB2-based composites co-doped with boron–titanium carbides

ZrB2-based ceramics were pressureless sintered at 2100 °C, with the co-incorporation of B4C and TiC. Levels of toughness as high as 4.1 ± 0.3 MPa m1/2 for ZrB2–TiB2–B4C and (6.5 ± 0.5) MPa m1/2 for ZrB2–SiC–TiB2–B4C were achieved. Carbon and TiB2 were formed in situ as densification aids. Carbon effectively removed surface oxide impurity, while TiB2 formed a solid solution with ZrB2, inhibiting grain growth and promoting densification. Other mechanical properties were also reported.