EFFECTS OF TiB2 CONTENT ON MICROSTRUCTURE AND MECHANICAL PROPERTY OF B4C--TiB2--Al COMPOSITES
TiB2含量对B4C-TiB2-Al复合材料组织与力学性能的影响

B4C-TiB2-Al composites were prepared by the method of infiltrating aluminum into B4C-TiB2 preform in vacuum. Investigations were carried out to analyze the effects of different content of TiB2 on the microstructure and properties of the composites. The results showed that B4C-TiB2-Al composite is mainly composed of B4C, TiB2, Al and Al3BC, and hardness decreases, bending strength increases and fracture toughness increases and then decreases lightly with the increase of TiB2 content,. Porosity, hardness, bending strength and fracture toughness of composite with 40 wt.% TiB2 are 1.32%, 80.3HRA, 559.4MPa and 7.83MPa m1/2 respectively. It was found that the toughening mechanism of the composites is mainly that the addition of aluminum, the diminishment of B4C and TiB2 grain size, the crack deflection and divarication caused by the difference in thermal expansion coefficient between the matrix B4C and the particle TiB2. The ratio of metal tear ridges and dimples increase while the ratio of intergranular fractures and transgranular fractures decrease in the fracture surface with the increase of aluminum content.