In-situ observation of dislocation dynamics during dislocation channel broadening

For the first time, this work revealed the dislocation dynamics during dislocation channel broadening through in-situ straining and radiation experiments in TEM. The study examines how the distribution of radiation-induced defects (mainly density and size) influences dislocation channel development. Serving as a follow-up study to our previous work (DOI: 10.1016/j.actamat.2024.119650), this paper provides direct evidence to visualize the root cause of dislocation channel broadening in additively manufactured (AM) 316L stainless steel (SS) after hot isostatic pressing (HIP) and compared to the wrought 316L SS. Radiation-induced defects were observed to pin the dislocation significantly, compared to the unirradiated condition, resulting in discontinued and segmented motion and constrained plastic flow through the dislocation channel. The distribution of radiation-induced defects in HIP AM 316L SS (smaller and denser defects) promoted more frequent out-of-plane cross-slip or double cross-slip, a key mechanism to form boarder dislocation channels than wrought counterpart.