The effect of deformation temperature on recrystallization in a Ni-based single crystal superalloys

A series of experiments have been carried out to investigate the effect of deformation temperature on the recrystallization of nickel-based single crystal superalloys using isothermal (compression) and non -isothermal (directional solidification) deformation. The recrystallization features induced by accumu-lated plastic strain in two temperature ranges (1300-1150 degrees C and 600-400 degrees C) are distinctly different from that induced by deformation in one temperature range (1300-1150 degrees C). The different recrystallized features (area and number of grains) induced by isothermal deformation at temperatures ranging from room temperature to solidus can be attributed to different dislocation features, such as slip band, KW -lock, gamma/gamma ' interfacial dislocations and Low Angle Boundary. Microscopic observations disclose that inter-actions of multiple slip systems have higher tendency of recrystallization. A close view between deformed and recrystallized samples of different deformation temperatures reveals that the critical ker-nel average misorientation (KAM) to induce recrystallization is about 0.4 degrees. Furthermore, the number of recrystallized grains is proportional with the average KAM value based on the experimental measure-ments in a wide temperature range. Isolated recrystallized grains are observed at the stress concentration locations in the low plastic strain zone due to local high misorientation. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).