Mechanical performance of sub-stoichiometric titanium carbide ceramics synthesized by a hybrid SHS and SPS methodology

Sub-stoichiometric titanium carbide ceramics were synthesized via a hybrid route combining self-propagating high-temperature synthesis (SHS) and spark plasma sintering (SPS). TiC₁₋ₓ powders were produced through a single, rapid SHS step by the direct reaction of titanium and graphite, followed by attrition milling to achieve an average particle size of 3–5 μm. Particular attention was devoted to analyzing sub-stoichiometry variations associated with carbon vacancy formation during both SHS and SPS processes. SPS treatments at temperatures up to 1800 °C promoted sub-stoichiometric deviations reaching compositions as low as TiC_0.74, which remained nearly stable even under more extreme SPS conditions. Additionally, a minor and unexpected precipitation of a disordered graphite phase was detected. The resulting sub-stoichiometric titanium carbide ceramics exhibited high Vickers hardness values, reaching up to 27 GPa. Microstructural analysis revealed plastic deformation, attributed to dislocation interactions with graphite precipitates. The dislocation dynamics were found to be governed by cationic diffusion mechanisms.