Microstructure evolution, enhanced hardness and toughness in the solid-solution ceramic composite by reaction pressureless sintering of ZrB_2 and TiC powders

摘要

Fully dense ZrB_2-TiC composites were produced by reactive pressureless sintering using ZrB_2 and TiC as the starting reactants. The effect of TiC content on microstructure and mechanical properties of ZrB_2-TiC composites was investigated. The densifcation and grain refnement were achieved due to the reaction and solid solution coupling effect. Besides, elongated (Ti, Zr)B_2 plate-like grains with a high aspect ratio were obtained for the frst time by the reaction of ZrB_2 and TiC. The ZrB_2-70 molTiC composite exhibited good comprehensive mechanical properties of high hardness of 29.0 GPa, fexural strength of 555 MPa, and fracture toughness of 5.4 MPa m~(1/2) due to grain-refnement and solid solution strengthening, and plate-like grains toughening effects.