Preferential grain boundary migration during annealing of cold-rolled pure Ni investigated by in-situ EBSD

The grain boundary migration behavior during annealing of cold-rolled pure Ni was systematically investigated through in-situ electron backscatter diffraction at 650 °C combined with the molecular dynamic simulation. At the grain scale, the migration kinetic was sensitive to the orientation relationship between recrystallized grains and the deformed matrix. The highest velocity of grain boundary migration was observed at a misorientation angle of approximately 50° between recrystallized and matrix grains, coupled with a ⟨111⟩-axis deviation of ∼10°. During the recrystallization, a large amount of Σ3 twin boundaries is formed owing to the migration of grain boundaries. Few irregular twin boundaries are also observed, whose formation is associated with the local stacking fault and thereafter grain encountering.