Kinetics of cellular discontinuous precipitation in a Re-containing single crystal superalloy

Cellular recrystallization behavior of a second generation single crystal superalloy DD6 was studied experimentally by annealing at sub-solvus temperature of 1100 °C in this work. During cellular growth, the microstructure in the direct vicinity of recrystallization reaction front was investigated by combined electron microscopy techniques. The results exhibited strong recovery and subgrain formation in the grit-blasted original matrix. Compositional mapping measured across the advancing recrystallization reaction front shows that a thin layer of γ-forming elements always exists in the recrystallization reaction front. By diffusion ahead and inside the reaction front, the chemical deviation from local equilibrium at the interface results in a force pulling the grain boundary forward.