A Cosserat crystal plasticity and phase field theory for grain boundary migration

TL;DR

This paper develops a unified, thermodynamically consistent diffuse interface model combining Cosserat crystal plasticity and phase field theory to simulate grain boundary migration and microstructure evolution in metals.

Contribution

It introduces an extended Kobayashi--Warren--Carter phase field model incorporating full mechanical coupling with crystal viscoplasticity and dislocation dynamics.

Findings

Successfully couples phase field with Cosserat plasticity for grain boundary migration.

Provides a framework for simulating concurrent deformation and recrystallization.

Enhances understanding of microstructure evolution in thermomechanical treatments.

Abstract

The microstructure evolution due to thermomechanical treatment of metals can largely be described by viscoplastic deformation, nucleation and grain growth. These processes take place over different length and time scales which present significant challenges when formulating simulation models. In particular, no overall unified field framework exists to model concurrent viscoplastic deformation and recrystallization and grain growth in metal polycrystals. In this work a thermodynamically consistent diffuse interface framework incorporating crystal viscoplasticity and grain boundary migration is elaborated. The Kobayashi--Warren--Carter (KWC) phase field model is extended to incorporate the full mechanical coupling with material and lattice rotations and evolution of dislocation densities. The Cosserat crystal plasticity theory is shown to be the appropriate framework to formulate the coupling between phase field and mechanics with proper distinction between bulk and grain boundary behaviour.