Thermodynamic and Experimental Evaluation of Sintering Pressure and Atmosphere in Ti(C,N)–FeNiCr Cermets

Ti(C,N) cermets with Fe-based binders are being investigated as potential substitutes for Co-containing systems, motivated by concerns related to critical raw materials. Beyond composition, the sintering process plays a key role in defining microstructure and properties. This study explores the influence of sintering pressure and atmosphere on binder volatilisation, nitrogen outgassing and densification in a Ti(C,N)–FeNiCr cermet. CALPHAD-based thermodynamic modelling is combined with experimental sintering cycles performed under controlled vacuum levels and gas partial pressures. High vacuum promoted evaporation of Cr and Fe from the liquid binder, whereas under medium vacuum only Cr depletion was observed; increasing the overall pressure limited these effects. Nitrogen outgassing was governed by the sintering atmosphere rather than the vacuum level, indicating that a N₂ partial pressure is required to preserve Ti(C,N) stoichiometry. Higher pressures were associated with coarser microstructures, and the influence of pressure cycling on phase formation was confirmed by X-ray diffraction. Among the conditions explored, combined sintering cycles incorporating gas injection at 1000 °C were associated with a favourable hardness–toughness balance, highlighting the importance of atmosphere control for managing microstructural development and properties. • Pressure and atmosphere effects during sintering of Ti(C,N)–FeNiCr cermets. • CALPHAD-assisted interpretation of phase stability and gas formation. • Selective evaporation of Cr and Fe occurs under high vacuum conditions. • Nitrogen stoichiometry is preserved only under N₂-containing atmospheres. • Pressure-controlled cycles enable improved mechanical performance.