Effect of carbon content on the microstructure and mechanical properties of Mo2FeB2 based cermets

Four series of Mo2FeB2 based cermets with different carbon contents were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The transverse rupture strength (TRS), hardness (HRA) and fracture toughness (KIC) were also measured. The free carbon present in the green compact significantly decreased the grain size; however, a high carbon content resulted in the formation of graphite phase and Fe3C phase. An increasing carbon content promoted the dissolution of Mo in the binder phase. In addition, the binder phase varied from ferrite to martensite with increasing carbon content. The highest hardness was found for the cermets with 0.5 wt.% carbon addition, whereas the cermets without carbon addition exhibited the maximum TRS and fracture toughness.

► The free carbon present in the green compact significantly decreased the grain size.
► Increasing carbon content resulted in the formation of graphite phase and Fe3C phase.
► The binder phase varied from ferrite to martensite with increasing carbon content.
► The mechanical properties can be tailored by the carbon content.