HRTEM and XPS characterizations for probable formation of TiBxNy solid solution during sintering process of TiB2–20SiC–5Si3N4 composite

The microstructural characterization of spark plasma sintered (SPSed) TiB2–20SiC–5Si3N4 composite was investigated precisely by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The in-situ phases generated during SPS process were studied using HSC chemistry software; the result shows the development of plausible reaction between Si3N4 and B2O3, forming h-BN. In addition, the formation of in-situ TiN phase and/or TiBxNy solid solution was confirmed by XPS analysis, attributed to the reaction between TiO2 and Si3N4. The intense interfaces were formed due to the coherency between hexagonal structures of TiB2, SiC, and BN phases as detected by HRTEM. Furthermore, weak interfaces were generated because of the formation of amorphous phases in the junctions. The presence of structural defects and distortions was demonstrated in both TiB2 and h-BN by inverse fast Fourier transform patterns, which can be considered as the main channels for the diffusion and transportation of boron atoms into the Si3N4 matrix for the formation of the in-situ h-BN phase.