Modelling grain growth in the framework of Rational Extended Thermodynamics
L. Kertsch, D. Helm,
Volume: 24.
DOI: 10.1088/0965-0393/24/4/045001
Published: #apr# 2016
Abstract
Grain growth is a significant phenomenon for the thermomechanical
processing of metals. Since the mobility of the grain boundaries
is thermally activated and energy stored in the grain boundaries
is released during their motion, a mutual interaction with the process
conditions occurs. To model such phenomena, a thermodynamic framework
for the representation of thermomechanical coupling phenomena in
metals including a microstructure description is required. For this
purpose, Rational Extended Thermodynamics appears to be a useful
tool. We apply an entropy principle to derive a thermodynamically
consistent model for grain coarsening due to the growth and shrinkage
of individual grains. Despite the rather different approaches applied,
we obtain a grain growth model which is similar to existing ones
and can be regarded as a thermodynamic extension of that by Hillert
(1965) to more general systems. To demonstrate the applicability
of the model, we compare our simulation results to grain growth experiments
in pure copper by different authors, which we are able to reproduce
very accurately. Finally, we study the implications of the energy
release due to grain growth on the energy balance. The present unified
approach combining a microstructure description and continuum mechanics
is ready to be further used to develop more elaborate material models
for complex thermo-chemo-mechanical coupling phenomena.