Phase field modelling of annealing twin formation, evolution and interactions during grain growth

Abstract

Grain boundary engineering involves manipulation of grain boundary character and network to improve the properties of materials. Twin boundaries which form during annealing of low and medium stacking fault energy face centered cubic materials play an important role in grain boundary engineering. In this work, we study the formation, growth, interactions and annihilation of annealing twins using a phase field model. The model incorporates twin formation through growth accidents on grain boundaries and triple junctions. The results indicate that higher stored energy gradients in the microstructure enhance the twin formation and their rate of growth. Also, recovery with a slower rate of stored energy decay increases twin formation events and delays the annihilation of the twins. The influence of the variant selection (based on the axes of misorientation of the twin boundaries with the parent grains) on the nature of their interactions with other twins and coincident site lattice boundaries is examined. The variant selection is found to affect the interactions of twins with other coincident site lattice boundaries thereby influencing the grain boundary character distribution.