Influence of triethylammonium decahydro-closo-decaborate on combustion behavior, phase composition, and microstructure of TiC-NiCr composites fabricated via self-propagating high-temperature synthesis

This study investigates the mechanism of self-propagating high-temperature synthesis (SHS) for the Ti-C-NiCr system with the addition of 1–10 wt% triethylammonium decahydro-closo-decaborate (Et3NH)2[B10H10] as a boron-containing modifier. The introduction of this additive significantly reduces the combustion temperature from 2050 to 630 °C, depending on its concentration. X-ray powder diffraction revealed the formation of secondary phases, including BNi2 and Ni3Ti, in the presence of the boron additive. At higher concentrations (7.5 and 10 wt%) additional phases such as Ni21Ti2B6 and Ti2CN were detected. The synthesized composites were characterized using scanning electron microscopy (SEM), energy-dispersive analysis (EDA), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). The results demonstrate that increasing the (Et3NH)2[B10H10] content leads to a substantial refinement of TiC and Ti2CN grains with a maximum reduction factor of 6.8 observed at 10 wt% additive compared to the boron-free reference. TEM analysis confirmed the presence of isometric, non-faceted particles in all samples. Particle size distribution analysis revealed a bimodal distribution for materials containing >1 wt% boron additive, whereas the boron-free sample and the 1 wt% variant exhibited a trimodal distribution. Additionally, IR spectroscopy confirmed the presence of adsorbed water molecules in all synthesized materials, irrespective of the initial reaction mixture composition. © 2025 Elsevier B.V.