Thermal Effects in Dislocation Theory

TL;DR

This paper reviews the effective-temperature theory in dislocation mechanics, emphasizing the importance of considering two thermodynamic temperatures to better understand and predict complex deformation behaviors like shear banding.

Contribution

It introduces a thermodynamically consistent reformulation of dislocation theories incorporating two temperatures, linking configurational and kinetic effects for improved predictive power.

Findings

Two-temperature framework explains shear-banding instabilities

Reformulation enhances understanding of dislocation dynamics

Bridges gap between thermodynamics and dislocation theory

Abstract

The mechanical behaviors of polycrystalline solids are determined by the interplay between phenomena governed by two different thermodynamic temperatures: the configurational effective temperature that controls the density of dislocations, and the ordinary kinetic-vibrational temperature that controls activated depinning mechanisms and thus deformation rates. This paper contains a review of the effective-temperature theory and its relation to conventional dislocation theories. It includes a simple illustration of how these two thermal effects can combine to produce a predictive theory of spatial heterogeneities such as shear-banding instabilities. Its main message is a plea that conventional dislocation theories be reformulated in a thermodynamically consistent way so that the vast array of observed behaviors can be understood systematically.