Effects of Cr content on the microstructure and mechanical properties of Mo2FeB2-based cermets prepared via vacuum sintering

Six series of cermet samples with Cr contents between 0 and 12.5 wt.% in 2.5 wt.% increments were prepared by vacuum sintering. The transverse rupture strength (TRS), hardness (HRA) and fracture toughness (K1C) were also measured. It was discovered that the grain size was affected by the Cr content. As the Cr addition increased, the average grain size and aspect ratio of the Mo2FeB2 hard phase decreased, while the lattice constant ratio c/a increased. Consequently, the particle morphology gradually transformed from elongated to nearly equiaxed. The transverse rupture strength and hardness of the cermets firstly increased and following decreased slightly as the Cr content increased, while the fracture toughness gradually decreased. The cermets with 10 wt.% of Cr addition exhibited the lowest grain size. The cermets with 10 wt.% of Cr addition demonstrated the TRS, hardness and fracture toughness values of 2124.1 MPa, 89.0HRA and 23.8 MPa m1/2, respectively.