Slip-free multiplication and complexity of dislocation networks in FCC metals

• Published in: Materials theory Vol. 5; no. 1; pp. 1 - 24
• Main Authors: Akhondzadeh, Sh, Bertin, Nicolas, Sills, Ryan B., Cai, Wei
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 29.03.2021; Springer Nature B.V; Springer Science + Business Media; SpringerOpen
• Subjects: Characterization and Evaluation of Materials; Characterization of Dislocation Ensembles: Measures and Complexity; Chemistry and Materials Science; Complexity; Condensed Matter Physics; Configurations; Cross slip; Crystal dislocations; Dislocation density; Evolution; Face centered cubic lattice; FCC metals; Line intersections; Materials Engineering; Materials Science; Multiplication; Original Article; Physical Chemistry; Plastic deformation; Strain rate
• ISSN: 2509-8012; 2509-8012
• DOI: 10.1186/s41313-020-00024-y

During plastic deformation of crystalline solids, intricate networks of dislocation lines form and evolve. To capture dislocation density evolution, prominent theories of crystal plasticity assume that 1) multiplication is driven by slip in active slip systems and 2) pair-wise slip system interactions dominate network evolution. In this work, we analyze a massive database of over 100 discrete dislocation dynamics simulations (with cross-slip suppressed), and our findings bring both of these assumptions into question. We demonstrate that dislocation multiplication is commonly observed on slip systems with no applied stress and no plastic strain rate, a phenomenon we refer to as slip-free multiplication. We show that while the formation of glissile junctions provides one mechanism for slip-free multiplication, additional mechanisms which account for the influence of coplanar interactions are needed to fully explain the observations. Unlike glissile junction formation which results from a binary reaction between a pair of slip systems, these new multiplication mechanisms require higher order reactions that lead to complex network configurations. While these complex configurations have not been given much attention previously, they account for about 50% of the line intersections in our database.