Enhancement of Ti(C,N)-Based Cermets by Aluminum Nitride: Binder Phase Strengthening and Microstructural Refinement

This study systematically investigated the influence of aluminum nitride (AlN) addition on the microstructure and mechanical properties of Ti(C,N)-based cermets with low Ni/Co and high N contents. The results demonstrate that AlN addition does not alter the phase composition of Ti(C,N)-based cermets, and their microstructure retains the characteristic core-rim morphology. The dissolution of Al atoms from AlN effectively suppressed abnormal growth of Ti(C,N) grains and enhanced the mechanical stability of the binder. Densification and comprehensive mechanical properties strongly depended on the AlN content. Both parameters initially improved with the addition of AlN, peaked at an optimal content of 1.0 wt.%, and then declined upon further addition due to the formation of micropores and brittle agglomerates of Al₂O₃. At the optimal AlN content of 1.0 wt.%, the cermets demonstrated peak performance: a Vickers hardness of 1676 HV30, a transverse rupture strength of 1486 MPa, and a fracture toughness of 8.8 MPa·m^1/2. The results elucidate the dual role of AlN as both a microstructural refiner and a precursor for in situ strengthening of the binder phase.