Short communicationSimultaneously enhanced toughness and strain tolerance of SiC-based ceramic composite by in-situ formation of VB2 particles

SiC-30vol%VB2 ceramic composite was pressureless densified at 2150 °C with excess B4C and C as sintering aids after in-situ formation of VB2 in SiC matrix. The sintered bulk gained a considerably high fracture toughness of 7.0 ± 0.4 MPa m1/2, which was ∼2.4 times as high as that of the monolithic SiC ceramic, owing to the existences of weak heterophase boundaries, thermal residual stresses and microcracks. Meanwhile, since the VB2 particle has a lower elastic modulus than SiC and significantly suppressed the grain growth of SiC, the composite exhibited a high flexural strength of 458 ± 36 MPa and a relatively low Young's modulus of 356 ± 6 GPa, resulting in an increase of ∼59.3% in mechanical strain tolerance (1.29 × 10−3) compared with that of single-phase SiC ceramic. Besides, the residual stresses and microcracks also induced a lower-than-expected Vickers hardness of 20.8 ± 0.5 GPa in the composite.