fig6

Figure 6. Expansion of a dislocation loop in the presence of segregations. The blue and red ovals denote the segregations that hinder and promote loop expansion, respectively. (A and B) Dislocation loop ends, A and B, which nucleate and expand under the action of the applied load, are pinned by segregations. (A) Projection on dislocation glide plane illustrating segregation-induced pinning. (B) Projection on grain boundary plane illustrating the fact that a segregation can either promote or hinder dislocation loop expansion, depending on the sign of the x2-coordinate of its center. (C) Dislocation loop expansion realized via its bow-out, thereby increasing the applied load if segregation-induced pinning is strong. (D) If pinning is weak, loop expansion is realized via the unpinning and lateral motion of points A and B. Reproduced with permission, Copyright 2019, Elsevier^[26].