Kinetics and Microstructures of Cellular Recrystallization of Single Crystal Superalloy DD6

Abstract

The samples of single crystal superalloy DD6 were grit blasted and heat treated at 1100°C for 0.5h, 1h, 2h, 4h, 8h, 16h at vacuum atmosphere, respectively, then the recrystallization microstructure and kinetics of DD6 alloy was investigated. The results showed that the cellular recrystallization grains nucleated in grit blasted single crystal samples heat treated at 1100°Cfor 0.5h, 1h, 2h, 4h, 8h, 16h. With the increase of the duration of heat heating process, the configuration of cellular recrystallization cleared up, and the depth of cellular recrystallization increased. While the coarse γ phase formed in the cellular recrystallization, and the shape of γ phases in the cellular recrystallization was almost equiaxed near the surface of the grit blasted samples and lamellar at the interface between cellular recrystallization and the original zone, respectively. The lamellar γ phase in the cellular grains was radial, and perpendicular to the cellular grain boundary. The recrystallization kinetics of single crystal superalloy DD6 was disclosed, with the increase of the duration of heat heating process, the depth of cellular recrystallization increase quickly and then almost keeps stable at last. The velocity of growth of cellular recrystallization increase very quickly at first, and then decrease at some stage, at last, the velocity tends to zero.