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Nanotwinned fcc metals: Strengthening versus softening mechanisms

Stukowski, A. and Albe, K. and Farkas, D. (2010):
Nanotwinned fcc metals: Strengthening versus softening mechanisms.
In: Phys. Rev. B, American Physical Society, p. 224103, 82, (22), [Online-Edition: http://prb.aps.org/abstract/PRB/v82/i22/e224103],
[Article]

Abstract

The strengthening effect of twins in nanocrystalline metals has been reported both in experiment and simulation. While twins are mostly considered as effective barriers to dislocation slip transfer, they can also provide nucleation sites for dislocations or migrate during the deformation process, thereby contributing to plasticity. By comparing twinned and nontwinned samples, we study the effect of twins on the deformation behavior of nanocrystalline Cu and Pd using atomistic simulations. While Cu shows hardening due to the presence of twins, Pd shows the opposite effect. A quantitative dislocation analysis method is applied, which allows to analyze dislocation interactions with twin planes and grain boundaries and to measure dislocation, stacking fault, and twin-boundary densities as functions of strain. A statistical analysis of the occurring dislocation types provides direct evidence for the role of twin boundaries as effective sources for twinning dislocations, which are the reason for the observed softening in some fcc materials. In addition, we discuss how the orientation of the loading direction with respect to the twin planes affects the response of nanotwinned Cu and Pd.

Item Type: Article
Erschienen: 2010
Creators: Stukowski, A. and Albe, K. and Farkas, D.
Title: Nanotwinned fcc metals: Strengthening versus softening mechanisms
Language: English
Abstract:

The strengthening effect of twins in nanocrystalline metals has been reported both in experiment and simulation. While twins are mostly considered as effective barriers to dislocation slip transfer, they can also provide nucleation sites for dislocations or migrate during the deformation process, thereby contributing to plasticity. By comparing twinned and nontwinned samples, we study the effect of twins on the deformation behavior of nanocrystalline Cu and Pd using atomistic simulations. While Cu shows hardening due to the presence of twins, Pd shows the opposite effect. A quantitative dislocation analysis method is applied, which allows to analyze dislocation interactions with twin planes and grain boundaries and to measure dislocation, stacking fault, and twin-boundary densities as functions of strain. A statistical analysis of the occurring dislocation types provides direct evidence for the role of twin boundaries as effective sources for twinning dislocations, which are the reason for the observed softening in some fcc materials. In addition, we discuss how the orientation of the loading direction with respect to the twin planes affects the response of nanotwinned Cu and Pd.

Journal or Publication Title: Phys. Rev. B
Volume: 82
Number: 22
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Date Deposited: 22 Feb 2012 16:19
Official URL: http://prb.aps.org/abstract/PRB/v82/i22/e224103
Identification Number: doi:10.1103/PhysRevB.82.224103
Related URLs:
Funders: The authors acknowledge the financial support of the Deutsche Forschungsgemeinschaft �FOR714� and the grants for computing time by the Forschungszentrum Jülich and bwGRiD, member of the German D-Grid initiative., D.F. acknowledges support from DOE, Basic Energy Sciences., K.A. is grateful for the hospitality experienced at Virginia Tech during his sabbatical leave.
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