【摘要】 以B4C,TiO2和石墨粉为原料,采用原位反应热压烧结工艺(2050℃,35MPa,1h)制备了致密的TiB2含量为10%～40%(体积分数)的TiB2/B4C复合材料,并对复合材料的组织结构和力学性能进行了研究。扫描电子显微镜和透射电子显微镜分析结果表明:在B4C晶内及晶界处均匀分布着纳米或亚微米级的TiB2颗粒,随着TiB2含量的增加,弹性模量和断裂韧性明显增大,而弹性模量和抗弯强度却随之减小。40%(体积分数)TiB2/B4C复合材料具有高的断裂韧性,高达8.2MPam1/2,主要增韧机制由微裂纹增韧和裂纹偏转增韧。更多还原

【Abstract】 The fully dense boron carbide matrix composites containing 10% 40% (volume fraction) TiB 2 (TiB 2 /B 4 C) were in-situ fabricated via chemical reaction of B 4 C, TiO 2 and graphite powders at 2 050 ℃ under a pressure of 35 MPa. Scanning electron microscopy (SEM) and transmission election microscopy (TEM) observations show that the sub-micron/nano-sized TiB 2 particles are uniformly located within the matrix grains and at the B 4 C grain boundaries. With the increase of TiB 2 content, the elastic modulus and fracture toughness of composites increase remarkably. However, the situation is reversed for Vickers hardness and flexural strength. The fracture toughness exhibits a maximum value of 8.2 MPa m 1/2 for the 40% (volume fraction) TiB 2 /B 4 C composite. The main toughening mechanisms of TiB 2 /B 4 C composites are microcrack toughening and crack deflection toughening.更多还原