Thermodynamic theory of dislocation-enabled plasticity

TL;DR

This paper develops a thermodynamic framework for understanding dislocation-driven plasticity, emphasizing an effective temperature and thermally activated depinning, to explain phenomena like strain hardening and shear banding.

Contribution

It reformulates the thermodynamic theory of dislocation plasticity, incorporating effective temperature and depinning mechanisms, to better explain experimental observations.

Findings

Effective temperature characterizes dislocation systems.

Depinning controls plastic deformation processes.

Theory explains strain hardening and shear banding phenomena.

Abstract

The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects, yielding transitions, and adiabatic shear banding.