Microstructure evolution, enhanced hardness and toughness in the solid-solution ceramic composite by reaction pressureless sintering of ZrB2 and TiC powders

Abstract

Fully dense ZrB2–TiC composites were produced by reactive pressureless sintering using ZrB2 and TiC as the starting reactants. The effect of TiC content on microstructure and mechanical properties of ZrB2–TiC composites was investigated. The densification and grain refinement were achieved due to the reaction and solid solution coupling effect. Besides, elongated (Ti, Zr)B2 plate-like grains with a high aspect ratio were obtained for the first time by the reaction of ZrB2 and TiC. The ZrB2-70 mol%TiC composite exhibited good comprehensive mechanical properties of high hardness of 29.0 GPa, flexural strength of 555 MPa, and fracture toughness of 5.4 MPa m1/2 due to grain-refinement and solid solution strengthening, and plate-like grains toughening effects.