B₄C‐TiB₂‐SiC composites toughened by (TiB₂‐SiC) agglomerates were prepared via reactive hot pressing with B₄C and TiSi₂ 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 TiB₂ 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·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 TiB₂ 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.

中文翻译：

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（TiB2-SiC）团聚增韧B4C-TiB2-SiC复合材料的显微组织和力学性能

通过反应热压，以B ₄ C和TiSi ₂为原料，制备了由（TiB ₂ -SiC）团聚体增韧的B ₄ C-TiB ₂ -SiC复合材料。研究了所制备复合材料的相组成，微观结构和力学性能。分析了（TiB ₂ -SiC）团聚体的功能，并讨论了其强化和增韧机理。结果表明，一些原位形成的TiB ₂和SiC互锁以在基质中形成特殊的（TiB ₂ -SiC）团聚体。510 MPa的抗折强度，5.84 MPa·m ^1/2的良好综合性能用30wt％的TiSi ₂制成的复合材料获得了断裂韧性和31.93GPa硬度。由于钉扎效应，原位引入的细TiB ₂和SiC晶粒细化了B ₄ C晶粒，从而提高了强度。特殊的（TiB ₂ -SiC）团聚体和由热膨胀系数不匹配引起的现有增韧现象（如裂纹挠曲，分支和微裂纹区域）对改善断裂韧性具有累积作用。