Simulating dislocation-solute interactions in dilute alloys to understand serrated flow

Simulations of solute-dislocation interactions using elasto-kinetic stochastic models reveal the conditions under which serrated flow occurs. Serrated flow is a deformation instability of some alloys by which they can lose ductility, and thus it is important to understand the mechanisms behind it.

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When a metal alloy is deformed, line defects called dislocations move, producing plastic slip as they do. In dilute alloys above a certain temperature, solutes may move as well, in some cases over time scales comparable to those of dislocation motion. From a physical point of view, studying this interplay is challenging because solute atoms need to be studied at atomistic length scales, but their diffusion often takes place over time scales much beyond those of atomic vibrations. We have developed elasto-kinetic stochastic models of dislocation-solute coevolution that allow us to bridge this scale gap and study the onset of serrated flow in structural alloys. This allow us to look at these processes on the length and time scales over which they truly occur, which will be helpful to understand how to design better materials that can avoid the detrimental effect of serrated plastic flow.

Jaime Marian

Professor, University of California Los Angeles