Λ-Invariant and Topological Pathways to Influence the Strength of Submicron Crystals

Stefanos Papanikolaou, Giacomo Po

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

In small volumes, sample dimensions are known to strongly influence mechanical behavior: Especially strength and crystal plasticity. This correlation fades away at the so-called "mesoscale," loosely defined at several micrometers in both experiments and simulations. However, this picture depends on the "entanglement" of the initial defect configuration. In this Letter, we study the effect of dislocation topology through the use of a novel observable for dislocation ensembles (the Λ invariant) that depends only on mutual dislocation linking: It is built on the natural vortex character of dislocations, and it has a continuum-discrete correspondence that may assist multiscale modeling descriptions. We investigate arbitrarily complex initial dislocation microstructures in sub-micron-sized pillars using three-dimensional discrete dislocation dynamics simulations for finite volumes. We demonstrate how to engineer nanoscale dislocation ensembles that are independent from sample dimensions, either by biased-random dislocation loop deposition or by sequential mechanical loads of compression and torsion.

Original languageEnglish (US)
Article number205502
JournalPhysical Review Letters
Volume124
Issue number20
DOIs
StatePublished - May 22 2020

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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