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Influence of hydrogen core force shielding on dislocation junctions in iron

Research output: Contribution to journalArticle

Haiyang Yu, Ivaylo H. Katzarov, Anthony T. Paxton, Alan C.F. Cocks, Edmund Tarleton

Original languageEnglish
Article number033607
JournalPhysical Review Materials
Volume4
Issue number3
DOIs
Publication statusPublished - Mar 2020

King's Authors

Abstract

The influence of hydrogen on dislocation junctions has been analyzed by incorporating a hydrogen-dependent core force into nodal-based discrete dislocation plasticity simulations. Hydrogen reduces the core energy of dislocations, which reduces the magnitude of the dislocation core force. We refer to this as hydrogen core force shielding, as it is analogous to hydrogen elastic shielding but occurs at much lower hydrogen concentrations. The dislocation core energy change due to hydrogen was calibrated at the atomic scale, accounting for the nonlinear interatomic interactions at the dislocation core, giving the model a sound physical basis. Hydrogen was found to strengthen binary junctions and promote the nucleation of dislocations from triple junctions. Simulations of microcantilever bend tests showed hydrogen core force shielding reduced the yield stress followed by increased strain hardening due to junction strengthening. These simulations demonstrate hydrogen effects at a small bulk hydrogen concentration, 10 appm, realistic for body-centered cubic iron, allowing micromechanical tests on hydrogen charged samples to be simulated.

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