Acoustic emission during heterogeneous and homogeneous plastic flow in metallic glass

Measurements of acoustic emission (AE) in the course of plastic deformation of metallic glass Co57Fe5Ni10Si11B17, subjected to diverse heat treatments have been taken. It is shown that at the same temperature and deformation rate, depending on preliminary annealing conditions, both a homogeneous flow realized without AE and localized flow accompanied by an intensive discrete AE are possible. The experimental results analysis suggested that the character of metallic glass flow is determined by structural relaxation rate at the temperature of testing: under conditions of intensive structural relaxation the plastic flow is homogeneous and viscoelastic, while under conditions of kinetically decelerated structural relaxation it is localized, being realized by dislocation-type mechanism