Molecular dynamics simulations of dislocation interaction with voids in nickel

• Published in: Computational materials science Vol. 50; no. 5; pp. 1811 - 1817
• Main Authors: Simar, Aude, Voigt, Hyon-Jee Lee, Wirth, Brian D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2011; Elsevier
• Subjects: Computer simulation; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Detachment; Dislocations; Dynamic effect; Dynamics; Exact sciences and technology; Interaction between different crystal defects; gettering effect; Molecular dynamics; Nickel; Obstacles; Physics; Strength; Stresses; Structure of solids and liquids; crystallography; Voids; Voids; Molecular dynamics; Nickel; Dislocations; Dynamic effect; Defect density; Cubic lattices; Ductility; Crystal defect interaction; Molecular dynamics method; Shear stress
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2011.01.020

Voids <2nm: discussion of the trailing partial dominated void detachment (Fig. 4). Voids >2nm: discussion of both partials dominated void detachment. Comparison with literature for the explanation of these mechanisms. Detachment angle independent of dynamic effects. Expression to obtain static stress from dynamic stress (Fig. 8). A high density of voids is expected to form in irradiated face centered cubic metals, which can have a negative impact on the ductility and cause an increasing strength. Molecular dynamics simulations of the interaction between gliding dissociated edge dislocations and voids in nickel have been performed to investigate the effect of the void size, the corresponding detachment mechanism, and dynamic effects of the dislocation on the obstacle strength. As expected, the void strength is observed to increase with increasing void size. The dislocation interaction and detachment process are determined by the applied shear stress, the repulsive interaction between partial dislocations and the image interaction between the partial dislocations and the void surface. For voids with a diameter smaller than 2nm, the repulsive stress between the partials dominates, resulting in the detachment of the leading partial from the void while the trailing partial remains pinned. Consequently, the detachment process and obstacle strength are controlled by the trailing partial. For voids with a diameter larger than 2nm, the attraction between the dissociated dislocations and the void dominates causing the detachment process and void strength to be influenced by both partials individually. This transition in detachment process at a void diameter of 2nm is consistent with other research, and this transition is shown to be dependent on the void separation distance along the dislocation line and the dissociation distance between the partials, thus the stacking fault energy. Finally, by comparing the quasi-static and dynamic simulation results, an estimate for the static detachment stress is proposed in terms of the dynamic detachment stress and the dislocation velocity after detachment.