Temporal dissipative structures in cyclically deformed metallic alloys

We have employed the modified Ananthakrishna non-linear dynamical model (proposed originally for the description of the Protevin-Le Chatelier effect in monotonically deformed metals [1]) in order to understand the nature of temporal instabilities in cyclically deformed metallic alloys. The model employs quasi-chemical reactions of multiplication, annihilation and positive feedback among the populations of mobile, immobile, and Cottrell-type dislocations [1]. Three major types of loading have been simulated, namely, pure sinusoidal, "creep fatigue", and ramp loading. Computer movies of the temporal evolution of stress serrations and dislocation densities have been produced as an aide for analysis and illustration. It has been demonstrated that the model successfully reproduces strain bursts and stress serrations in fatigued metallic alloys in terms of the underlying dislocations mechanisms, thus establishing the fundamental connection between micro-and macromechanics of cyclic deformation.