Microstructural mechanism of local dynamic recrystallization around cavity during tertiary creep in directionally solidified superalloy CM247LC
Dong‐Soo Kang, Hyungsoo Lee, Dae Won Yun, Hi Won Jeong, Young-Soo Yoo, Seong-Moon Seo
Abstract
This study investigated the mechanism of nucleation and growth of dynamic recrystallization (DRX) locally occurring around a cavity depending on the creep strain at 982 °C under 180 MPa in directionally solidified superalloy CM247LC. Misorientation increased when the creep strain reached 15%, and low-angle boundaries along rafted γ–γ’ around the cavity formed a high-angle boundary, which is assumed to be the initial nucleation mechanism of recrystallization. Further deformation increased the dislocation density in the recrystallized grains, resulting in post-DRX via fast dynamic recovery. The γ matrix was coarsened by the atomic diffusion of Co and Cr along the dislocation line in the γ’ phase of the recrystallized grains.