Combustion synthesis of TiCx–TiB2 composites with hypoeutectic, eutectic and hypereutectic microstructures

Self-propagating high-temperature synthesis (SHS) of compacted blends of Ti, B4C and/or C powders was used to fabricate in situ TiCx–TiB2 composites with different compositions. The microstructures of the resultant products were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), and the reaction sequence in the SHS reaction process was explored by quenching the combustion wavefront. The results showed that the TiCx–TiB2 composites with 27.4, 36.7 and 61.7% TiB2 in molar fractions display hypoeutectic, eutectic and hypereutectic microstructures, respectively, and TiCx is the leading phase in formation of the eutectic phase during solidification. Moreover, substoichiometric TiCx forms prior to TiB2 in phase formation sequence even for the hypereutectic composition sample.