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Atomistic mechanism of shock-induced void collapse in nanoporous metals

Erhart, P. and Bringa, E. M. and Kumar, M. and Albe, K. (2005):
Atomistic mechanism of shock-induced void collapse in nanoporous metals.
In: Phys. Rev. B, American Physical Society, pp. 052104-1, 72, (5), [Online-Edition: http://prb.aps.org/abstract/PRB/v72/i5/e052104],
[Article]

Abstract

We have investigated the microstructural changes in ductile porous metals during high pressure-high strain rate loading employing atomistic simulations and explored their relation to recent experiments on polycrystalline copper samples. Molecular-dynamics simulations of shocks in porous, single-crystal samples show the formation of nanograins due to localized massive plastic deformation induced by the presence of voids. In the process of grain formation the individual voids serve as dislocation sources. The efficiency of these sources is further enhanced by their collective interaction which eventually leads to very high dislocation densities. In agreement with experimental studies, the simulations display a temporal delay of the particle velocity in comparison to perfectly crystalline samples. This delay increases with porosity. Our results point towards the importance of void-void interactions and collective effects during dynamic loading of porous materials.

Item Type: Article
Erschienen: 2005
Creators: Erhart, P. and Bringa, E. M. and Kumar, M. and Albe, K.
Title: Atomistic mechanism of shock-induced void collapse in nanoporous metals
Language: English
Abstract:

We have investigated the microstructural changes in ductile porous metals during high pressure-high strain rate loading employing atomistic simulations and explored their relation to recent experiments on polycrystalline copper samples. Molecular-dynamics simulations of shocks in porous, single-crystal samples show the formation of nanograins due to localized massive plastic deformation induced by the presence of voids. In the process of grain formation the individual voids serve as dislocation sources. The efficiency of these sources is further enhanced by their collective interaction which eventually leads to very high dislocation densities. In agreement with experimental studies, the simulations display a temporal delay of the particle velocity in comparison to perfectly crystalline samples. This delay increases with porosity. Our results point towards the importance of void-void interactions and collective effects during dynamic loading of porous materials.

Journal or Publication Title: Phys. Rev. B
Volume: 72
Number: 5
Publisher: American Physical Society
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 28 Feb 2012 15:00
Official URL: http://prb.aps.org/abstract/PRB/v72/i5/e052104
Identification Number: doi:10.1103/PhysRevB.72.052104
Related URLs:
Funders: This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48., We would like to thank the ASCI-DOM program for partial financial support.
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