Interaction of extended dislocations with nanovoid clusters

TitleInteraction of extended dislocations with nanovoid clusters
Publication TypeJournal Article
Year of Publication2023
AuthorsRoach, Ashley M., Shuozhi Xu, Darby J. Luscher, Daniel S. Gianola, and Irene J. Beyerlein
JournalInternational Journal of Plasticity
Volume168
Pagination103684
ISSN0749-6419
KeywordsDislocations, Inhomogeneous metallic material, Phase-field dislocation dynamics, Strengthening mechanisms, Voids and inclusions
Abstract

Voids of nanoscale dimensions in irradiated metals can act as obstacles to dislocation motion and cause strengthening. In this work, nanovoid strengthening and the influences of void size, void spacing and material properties, such as stacking fault energies, on dislocation bypass mechanisms are investigated using Phase Field Dislocation Dynamics, a three-dimensional mesoscale model that predicts the minimum energy pathway taken by discrete dislocations. A broad range of face centered cubic metals (copper, nickel, silver, rhodium, and platinum) and nanovoid sizes and spacings are treated, altogether spanning void size–to–dislocation stacking fault width ratios from less than unity to ten. Material γ-surfaces, calculated from ab initio methods, are input directly into the formulation. The analysis reveals that the critical bypass stress scales linearly with the linear void fraction, effective isotropic shear modulus, and ratio of the intrinsic to unstable stacking fault energies. With only a few exceptions, the critical stress is controlled by the stress required for the leading partial to impinge the voids (to move within range of the attractive image stress field of the void). When the void diameter is nearly an order of magnitude greater than the stacking fault width, the mechanism determining critical strength shifts to the stress for the dislocation to breakaway after partially cutting the void. This situation corresponds to that treated by line tension models and is realized here for Pt, with a sub-nanometer stacking fault width.

URLhttps://www.sciencedirect.com/science/article/pii/S0749641923001705
DOI10.1016/j.ijplas.2023.103684