Phase‐field simulation and experimental validation of Mo‐doping effects on NbC–Ni cermets during liquid phase sintering

Abstract This study presents a multiphase and phase‐concentration modeling framework, coupled with CALculation of PHAse Diagrams (CALPHAD) databases, to simulate microstructural evolution during the intermediate stage of liquid phase sintering in NbC–Ni‐based cermets. The effect of varying Mo content (0, 5, 10, 15 wt.%) on NbC grain coarsening was systematically investigated through quantitative phase‐field simulations validated against experiments. Increasing Mo content causes smaller particle size and reduces solid volume fraction, manifesting enhanced grain growth inhibition. The dissolution of Mo suppresses grain coarsening by increasing the interfacial energy ratio, reducing the dihedral angle, preventing the formation of sintering neck, and increasing liquid volume fraction. A 10 wt.% Mo addition in NbC–Ni cermets improves Vickers hardness by 25% but decreases fracture toughness by 43%, while with 15 wt.% Mo, the hardness–toughness trade‐off reverses. These findings underscore the critical role of Mo doping in tailoring microstructure and optimizing the balance between hardness and fracture toughness.