Kinetics and microstructural evolution during recrystallization of a single crystal superalloy

The kinetical recrystallization behaviors over wide ranges of annealing temperature of 1100-1200 °C and annealing time range of 0.5-16 h of a second-generation single-crystal superalloy have been investigated by combined model simulation, TEM and EBSD techniques. The kinetics represented by Johnson-Mehl-Avrami and Arrhenius equations revealed its complicated diffusion-controlled mechanism. With increasing annealing temperature and time, the recrystallized grain size exhibited a steady increasing tendency, and gradually, the subgrain boundaries in the original matrix were consumed and replaced by high angle grain boundaries, leading to improved Schmid factor. The dominant fraction of twins in the resultant microstructure indicated its significant role in strain energy dissipation, facilitating the complete progress of recrystallization.