Influence of the microstructure evolution of ZrO2 fiber on the fracture toughness of ZrB2-SiC nanocomposite ceramics

► ZrO2(f)/ZrB2-SiC composites were fabricated by the SPS method. ► Fracture toughness of the ZrO2(f)/ZrB2-SiC composites can reach to 6.56 MPa m1/2. ► The microstructure change of ZrO2 fibers is good of fracture toughness increase. ► We detect that the structure of ZrO2 fibers changes from t-ZrO2 to m-ZrO2.