Abstract
Some new data on the effect of chromium diboride additives (within a range from 0 to 10 wt %) on the phase formation and physicomechanical properties (fracture toughness, hardness, ultimate bending and compression strength) of composite materials based on the WC–6 wt % Co hard alloy formed by cold pressing with further vacuum hot pressing are reported. It has been revealed that the sintered samples of composites are composed of the structural phases of hexagonal WC and orthorhombic B2CoW2 groups and amorphous carbon inclusions. In this case, the parameters of crystalline B2CoW2 are varied depending on the CrB2 content. It has also been established that the addition of 4 wt % of chromium diboride to the WC–6Co composite leads to a two-fold increase in the fracture toughness (from KIc of 9.8 to 14.5 MPa m1/2) with a slight decrease in the hardness H from 15.1 to 13.9 GPa and also to an increase in the ultimate bending strength Rbm from 2000 to 2500 MPa and the ultimate compression strength Rcm from 5300 to 5500 MPa. It has been shown that the mentioned parameters are attained due to the dispersion mechanism of reinforcement with transformations in the structure (a stable decrease in the average grain size of the carbide phase, the disappearance of pores in the location of the binding Co phase, the formation of inhibitor phase clusters at phase interfaces) and phase composition of the composites.