2015-Sustainable Industrial Processing Summit
SIPS 2015 Volume 1: Aifantis Intl. Symp. / Multiscale Material Mechanics
| Editors: | Kongoli F, Bordas S, Estrin Y |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2015 |
| Pages: | 300 pages |
| ISBN: | 978-1-987820-24-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Microstructurally Based Cross-Slip Mechanisms and Their Effects on Dislocation Microstructure Evolution in FCC Crystals
Jaafar El-Awady1; Ahmed Hussein1;1JOHNS HOPKINS UNIVERSITY, Baltimore, United States;
Type of Paper: Regular
Id Paper: 232
Topic: 1
Abstract:
Strain hardening in crystals and the accompanying dislocation pattern evolution (in the form of cell-like structures) are among the most difficult self-organizing behaviors to predict and explain. Screw character dislocation cross-slip has been typically presumed to play the main role in dislocation cell structure formation. However, many open questions remain regarding this mechanism. Recent molecular dynamics simulations showed that two cross-slip mechanisms, namely, surface and intersection mediated cross-slip mechanisms, exhibit a considerably lower activation energy than the traditionally accepted Friedel-Escaig cross-slip mechanism. In this work, we present the results of implementing these newly identified cross-slip mechanisms into discrete dislocation dynamics (DDD) simulations of nickel microcrystals, ranging in size from 0.5 to 20 microns in diameter. The conditions for each mechanism are discussed, along with their statistics and frequencies. The results show that dislocation cell structures form in simulation cells having diameters greater than 5 microns, as the dislocation density increases with increasing plastic strain. Smaller simulations cells, however, do not show any considerable cell formation at small strains as compared to the lager cells. The findings agree with recent experimental observations.