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Atomistic and Continuum Studies of Diffusional Creep and Associated Dislocation Mechanisms in thin Films on Substrates

Published online by Cambridge University Press:  15 February 2011

Markus J. Buehler ,
Alexander Hartmaier  and
Huajian Gao
Markus J. Buehler
Affiliation:
Max Planck Institute for Metals Research, 70569 Stuttgart, Germany
Alexander Hartmaier
Affiliation:
Max Planck Institute for Metals Research, 70569 Stuttgart, Germany
Huajian Gao
Affiliation:
Max Planck Institute for Metals Research, 70569 Stuttgart, Germany
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Abstract

Motivated by recent theoretical and experimental progress, large-scale atomistic simulations are performed to study plastic deformation in sub-micron thin films. The studies reveal that stresses are relaxed by material transport from the surface into the grain boundary. This leads to the formation of a novel defect identified as diffusion wedge. Eventually, a crack-like stress field develops because the tractions along the grain boundary relax, but the adhesion of the film to the substrate prohibits strain relaxation close to the interface. This causes nucleation of unexpected parallel glide dislocations at the grain boundary-substrate interface, for which no driving force exists in the overall biaxial stress field. The observation of parallel glide dislocations in molecular dynamics studies closes the theory-experiment-simulation linkage. In this study, we also compare the nucleation of dislocations from a diffusion wedge with nucleation from a crack. Further, we present preliminary results of modeling constrained diffusional creep using discrete dislocation dynamics simulations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 779: Symposium W – Multiscale Phenomena in Materials - Experiments and Modeling Related to Mechanical Behavior , 2003 , W4.7
Copyright
Copyright © Materials Research Society 2003

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