Fe-Ni binder modified NbC cermets: A cost-effective solution with superior mechanical properties

NbC-Ni cermets have emerged as promising alternatives to the conventional WC-Co due to their superior hot hardness and fracture toughness. However, the recent increase in Ni and Co prices necessitates substituting these binders with economical alternatives for cermet formulations. The Fe-Ni binary alloy shows promise as a binder due to its superior mechanical properties, low cost, and reduced toxicity compared to Co and Ni. This study demonstrated the potential of Fe-Ni as a promising binder material for NbC cermets, offering a balance between cost-effectiveness and properties suitable for various high-performance applications. The NbC-Fe-Ni cermets were fabricated via vacuum Liquid Phase Sintering (LPS) at 1440 degrees C for 1h and compared to NbC-Ni cermets. Microstructural analysis (SEM + EDX) revealed a continuous decrease in D90 values up to NbC-35Ni-65Fe (65 wt % Fe), indicating that Fe-Ni effectively suppressed grain growth; additionally, it increased the contiguity of NbC grains. Vickers hardness tests revealed that the hardness of the cermets increased with higher Fe content in the binder, reaching a peak value of 1487 +/- 15 HV30 for NbC-35Ni-65Fe, marking a remarkable 34 % improvement over NbC-Ni. However, fracture toughness decreased marginally due to the increased contiguity of NbC grains, which reduced crack inhibition. Nanoindentation hardness tests of the binder phase revealed that partial substitution of Ni with Fe enhanced binder hardness, contributing to the overall improvement in NbC-Fe-Ni cermets' hardness values. A 3-point bend test demonstrated a maximum strength of 649 +/- 16 MPa for NbC-35Ni-65Fe cermet, indicating a 19 % improvement over NbC-Ni cermet. These findings highlight Fe-Ni's potential as a cost-effective binder for NbC cermets, suitable for high-performance applications.