Microstructure and mechanical property of (TiB2-SiC) agglomerate-toughened B4C-TiB2-SiC composites

B4C-TiB2-SiC composites toughened by (TiB2-SiC) agglomerates were prepared via reactive hot pressing with B4C and TiSi(2)as raw materials. Phase composition, microstructure, and mechanical properties of the fabricated composites were investigated. The function of (TiB2-SiC) agglomerates was analyzed, and the strengthening and toughening mechanism were also discussed. Results indicated that some of the in situ formed TiB(2)and SiC were interlocked to form special (TiB2-SiC) agglomerates in the matrix. The good comprehensive performances of 510 MPa flexural strength, 5.84 MPa center dot m(1/2)fracture toughness, and 31.93 GPa hardness were obtained in the composites fabricated with 30 wt% TiSi2. The in situ introduced fine TiB(2)and SiC grains refined the grains of B4C due to the pinning effect, which enhanced the strength. The special (TiB2-SiC) agglomerates and the existing toughening phenomena such as crack deflection, branching, and microcrack regions induced by the mismatch of thermal expansion coefficients, had cumulative effects on improving the fracture toughness.