Nanostructure and nanoindentation study of pulse electric-current sintered TiB₂-SiC-C_f composite

A carbon-fiber (C_f) doped TiB₂-SiC composite was prepared and investigated to determine its densification behavior, micro/nanostructural properties, and mechanical characteristics. TiB₂-25 vol% SiC-2 wt% C_f was prepared at 40 MPa and 1800 °C for 7 min using the pulsed electric-current sintering technique, and a relative density of 98.5% was realized. The as-sintered composite was characterized using advanced techniques, e.g., X-ray diffractometry, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, field-emission electron probe micro-analysis, and nanoindentation. The C_f additive could remove the surface oxide layers from the TiB₂ and SiC domains, thus transforming them into TiB₂ and SiC. According to micro/nanostructural studies, C_f could not retain its initial structure and was eventually converted into graphite nanosheets. In addition, the prepared composite was examined using the nanoindentation technique, and the following results were obtained for the calculated hardness, elastic modulus, and stiffness values: TiB₂ > SiC > TiB₂/SiC interface.