Conditions of the formation and development of shear bands in amorphous metallic alloys

A mesostructural model of the development of shear bands in amorphous metallic alloys is suggested. To derive the conditions for the propagation of shear bands, the energetic approach is employed with the use of an important concept of fracture mechanics-the J integral. For a shear band, a coefficient of stress intensity is introduced, which expresses the measure of stress concentration at the tip of a shear band and permits one to describe the conditions of the development of heterogeneous plastic flow for various conditions of loading of samples of certain geometry. The local-deformation curve of amorphous alloys is analyzed, which is expressed through microscopic parameters of plasticity of these materials. The distribution of displacements and stresses induced by a shear band has been calculated, and the size of the end region in which the shear stress falls off from the threshold value for the development of localized flow to the stationary value has been estimated. The condition for the formation of shear bands at stress concentrators is considered.