The process of crack propagation from the pore in the modeled microstructure of the submicron and the nanostructured WC/Co hard alloys with the different volume fraction of the cobalt was studied. Strengths of its alloys were defined. Equivalence of the energy release rate with the fracture toughness of the components was the criterion of crack propagation through cobalt interlayers and carbide grains. To calculate energy release rate the modeling of stress state was carried out using finite element method. It has been shown, stresses necessary for crack propagation reach of maximal value when crack propagation to middle cobalt interlayer.