Solidification structure and crystal growth of the TiC-TiB2 fine-grained ceramics which was prepared by combustion synthesis under high gravity were investigated

and the relationship between microstructure and fracture behavior as well as toughening mechanism was analyzed by XRD（X-ray diffraction）

FESEM（field emission scanning electron microscope） and EDS（energy dispersive spectrometer）.The results show that the composite ceramics matrix is composed of a lot of fine TiB2 platelets and irregular TiC grain surrounded the TiB2 platelets.The formation of TiB2 platelets is resulted from faceted crystal growth while irregular TiC grains are the results of non-faceted crystal growth and high growth velocity.Relative density

Vickers hardness

bending strength and fracture toughness of the ceramics reach 98.6%

21.8 GPa

650MPa and 12.5 MPa·m1/2

respectively.Ceramic toughening mechanism is attributed to the co-operation of crack deflection

crack-bridging and pull-up by small-size TiB2 platelets and frictionally-interlocking in-situ toughening effects.