Room and high temperature toughening in directionally solidified B4C–TiB2 eutectic composites by Si doping

Abstract

Directionally solidified В4С–TiB2 eutectics doped with different Si contents were prepared by floating zone method. Silicon doping (up to 3vol.%) promotes a more coherent interface between B4C matrix and TiB2 inclusions, a decrease of the spacing between TiB2 (when solidification rate is constant), and formation of a more uniform morphology with thinner inclusions. These features lead to simultaneous enhancement of Vickers hardness (HV), fracture toughness (K1c) and bending strength (σ) when compared with Si-free В4С–TiB2 eutectics. For our materials, the average HV, K1c and σ were 45.2GPa, 7.04MPam1/2, and 460MPa at room temperature or 487MPa at 1600°C, respectively. The values of σ at indicated temperatures are approximately twice higher than for the Si-free В4С–TiB2 eutectic composites.