Twinning in certain metals or under certain conditions was a major plastic deformation mode. Here a phase field model was used to describe twin formation and evolution in a polycrystalline face-centered cubic metal under loading and unloading. The model assumed that twin nucleation, growth and de-twinning was a process of partial dislocation nucleation and slip on successive habit planes. Stacking fault energies, energy pathways (γ surfaces), critical shear stresses for the formation of stacking faults and dislocation core energies were used to construct the thermodynamic model. The simulation results demonstrate that the model was able to predict the nucleation of twins and partial dislocations, as well as the morphology of the twin nuclei, and to reasonably describe twin growth and interaction. The twin microstructures at grain boundaries were in agreement with experimental observation. It was found that de-twinning occurs during unloading in the simulations, however, a strong dependence of twin structure evolution on loading history was observed.

Simulations of Stress-Induced Twinning and De-Twinning: a Phase Field Model. S.Hu, C.H.Henager, L.Chen: Acta Materialia, 2010, 58[19], 6554-64