High strength B4C–TiB2 composites fabricated by reaction hot-pressing

主要内容：

1. 以B4C，TiO2, C粉为原料，热压反应烧结（2000oC，50 MPa）制备了完全致密的B4C-20mol%TiB2复相陶瓷，TiB2相为原位生成。

2. B4C 原料中有不同含量的金属Fe, Al作为烧结助剂。Fe，Al含量越高，所得材料的致密性越好，但是原位生成的TiB2尺寸也越大（液相的影响）。

3. 无论是从致密度还是机械性能，复相陶瓷都远由于单相B4C陶瓷。

4. 四点抗弯强度（inner 10 mm，outer 30 mm）最高达866 MPa。

4. 缺点：采用了低熔点金属作为烧结助剂，影响硬度及高温性能。

重要句子：

1. The growth of TiB2 particles in a B4C–TiB2 composite occurs mainly through the diffusion along the B4C grain boundaries.

2. The abnormal grain growth of B4C was inhibited by TiB2 particle dispersion for the B4C-TiB2 specimen.

3. The thermal expansion coefficient of TiB2 is larger than that of the B4C matrix, such that residual stress is generated around the TiB2 particles during cooling. This residual stress results in the formation of microcracks and, to some degree, deflection of propagating cracks, which leads to improvement in fracture toughness of composite materials.