Phase field modelling of grain boundary motion driven by curvature and stored energy gradients. Part II : application to recrystallisation
Résumé
In this work, the coupled phase field-crystal plasticity constitutive framework proposed in a companion publication [G. Abrivard, E.P. Busso, S. Forest and B. Apolaire, Phil. Mag. (2012) (this issue)] is applied to study the microstructural evolution driven by grain boundary curvature and/or stored energy. Different microstructures involving bicrystals and polycrystals of pure Al are studied and the results compared against experimental data and known analytical solutions. First, the study of a bicrystal with only curvature as the driving force for boundary migration enables the model to reproduce the different mobilities between low and high angle grain boundaries in the absence of Σ-type boundaries, and to identify the threshold misorientation below which the mobility is negligible. The growth of a small dislocation-free grain embedded within a highly deformed one is considered having both curvature and stored energy as the competing driving forces. A parametric study enabled the effect of the initial size of the nucleus on the minimum level of stored energy required for grain migration to be quantified. Finally, a study of recrystallisation and grain growth phenomena on a representative polycrystal aggregate revealed that grains with the lowest stored energy are dominant at the end of the recrystallisation process. The predicted recrystallised material volume fraction evolution and the kinetics of recrystallisation and grain growth were found to have the same dependence on deformation levels and temperature as those reported in the literature. Several outstanding modelling issues are identified and suggestions for further developments are discussed.