A coupled vacancy diffusion-dislocation dynamics model for the climb-glide motion of jogged screw dislocations. (1st January 2023)

• Record Type: Journal Article
• Authors: Li, Yang; Ghoniem, Nasr; Baker, Kristopher; Ramirez Flores, Benjamin; Black, Thomas; Hollenbeck, James; Po, Giacomo
• Is Part Of: Acta materialia. Volume 244(2023)
• Publication Date: 2023-01-01
• Subjects: Climb -- Creep rate -- Zirconium -- Dislocation dynamics; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2022.118546
• Languages: English
• ISSNs: 1359-6454

Abstract

Graphical abstract: Abstract: We develop a novel model to study the climb/glide motion of jogged screw dislocations within the discrete dislocation dynamics (DDD) framework. We present results for the dependence of the climb velocity on the applied stress and on the jog size and distribution statistics. We show that the model predictions are consistent with experimental data in both γ -TiAl and Zircaloy-4. The ranges of the applied stress and jog spacing that determine the dominance of one of three dislocation mechanisms are identified. These are the jog dragging, dipole dragging, and dipole bypass mechanisms, respectively. The overall dislocation motion in the jog dragging regime is composed of glide of screw segments and climb of jogs, controlling the plastic strain and the creep rate, respectively. Based on current simulations and on a detailed examination of the predicted jog heights compared to experiments, we advance the hypothesis that a combination of jog dragging and dipole bypass mechanisms is necessary to reproduce the high creep rate observed in some experiments.