Interfaces within strain gradient plasticity

Theory and experiments

Katerina E Aifantis, W. A. Soer, J. Th M De Hosson, J. R. Willis

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

In this paper, it is shown that the occurrence of dislocation pileups across grain boundaries, as well as subsequent emission to the adjacent grains, is captured theoretically by gradient plasticity and confirmed experimentally by nanoindentation. From a theoretical point of view, this is accomplished (within a deformation theory framework applicable to continued loading) by accounting for a specific interfacial term in the overall potential of the material, in terms of which its response, taken to conform to strain gradient plasticity, is defined. The main features that result from the addition of this interfacial term are (i) significant size effects of Hall-Petch type in the overall stress-strain response of polycrystals and (ii) the determination of an analytical expression for the stress corresponding to the onset of dislocation transfer across interfaces. From an experimental point of view, the effective stress at which dislocation transfer takes place across an interface can be obtained from nanoindentations performed in close proximity to an Fe-2.2 wt.% Si grain boundary, since they exhibit a distinct strain burst that is related to the presence of the boundary. It is possible, therefore, to fit the theoretically determined analytical expression for the interfacial yield stress to the experimental data. From this fit, first estimates are obtained for key material parameters, namely the interfacial term and the internal length, that are required for the theoretical formulation. Dislocation mechanics are employed to provide physical insight of these parameters.

Original languageEnglish (US)
Pages (from-to)5077-5085
Number of pages9
JournalActa Materialia
Volume54
Issue number19
DOIs
StatePublished - Nov 2006
Externally publishedYes

Fingerprint

Plasticity
Nanoindentation
Grain boundaries
Experiments
Polycrystals
Dislocations (crystals)
Yield stress
Mechanics

Keywords

  • Dislocations
  • Fe-Si bicrystal
  • Grain boundary
  • Nanoindentation
  • Plasticity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Science(all)
  • Metals and Alloys

Cite this

Interfaces within strain gradient plasticity : Theory and experiments. / Aifantis, Katerina E; Soer, W. A.; De Hosson, J. Th M; Willis, J. R.

In: Acta Materialia, Vol. 54, No. 19, 11.2006, p. 5077-5085.

Research output: Contribution to journalArticle

Aifantis, Katerina E ; Soer, W. A. ; De Hosson, J. Th M ; Willis, J. R. / Interfaces within strain gradient plasticity : Theory and experiments. In: Acta Materialia. 2006 ; Vol. 54, No. 19. pp. 5077-5085.
@article{ede465b01ef14e81bc811ef43284f68d,
title = "Interfaces within strain gradient plasticity: Theory and experiments",
abstract = "In this paper, it is shown that the occurrence of dislocation pileups across grain boundaries, as well as subsequent emission to the adjacent grains, is captured theoretically by gradient plasticity and confirmed experimentally by nanoindentation. From a theoretical point of view, this is accomplished (within a deformation theory framework applicable to continued loading) by accounting for a specific interfacial term in the overall potential of the material, in terms of which its response, taken to conform to strain gradient plasticity, is defined. The main features that result from the addition of this interfacial term are (i) significant size effects of Hall-Petch type in the overall stress-strain response of polycrystals and (ii) the determination of an analytical expression for the stress corresponding to the onset of dislocation transfer across interfaces. From an experimental point of view, the effective stress at which dislocation transfer takes place across an interface can be obtained from nanoindentations performed in close proximity to an Fe-2.2 wt.{\%} Si grain boundary, since they exhibit a distinct strain burst that is related to the presence of the boundary. It is possible, therefore, to fit the theoretically determined analytical expression for the interfacial yield stress to the experimental data. From this fit, first estimates are obtained for key material parameters, namely the interfacial term and the internal length, that are required for the theoretical formulation. Dislocation mechanics are employed to provide physical insight of these parameters.",
keywords = "Dislocations, Fe-Si bicrystal, Grain boundary, Nanoindentation, Plasticity",
author = "Aifantis, {Katerina E} and Soer, {W. A.} and {De Hosson}, {J. Th M} and Willis, {J. R.}",
year = "2006",
month = "11",
doi = "10.1016/j.actamat.2006.06.040",
language = "English (US)",
volume = "54",
pages = "5077--5085",
journal = "Acta Materialia",
issn = "1359-6454",
publisher = "Elsevier Limited",
number = "19",

}

TY - JOUR

T1 - Interfaces within strain gradient plasticity

T2 - Theory and experiments

AU - Aifantis, Katerina E

AU - Soer, W. A.

AU - De Hosson, J. Th M

AU - Willis, J. R.

PY - 2006/11

Y1 - 2006/11

N2 - In this paper, it is shown that the occurrence of dislocation pileups across grain boundaries, as well as subsequent emission to the adjacent grains, is captured theoretically by gradient plasticity and confirmed experimentally by nanoindentation. From a theoretical point of view, this is accomplished (within a deformation theory framework applicable to continued loading) by accounting for a specific interfacial term in the overall potential of the material, in terms of which its response, taken to conform to strain gradient plasticity, is defined. The main features that result from the addition of this interfacial term are (i) significant size effects of Hall-Petch type in the overall stress-strain response of polycrystals and (ii) the determination of an analytical expression for the stress corresponding to the onset of dislocation transfer across interfaces. From an experimental point of view, the effective stress at which dislocation transfer takes place across an interface can be obtained from nanoindentations performed in close proximity to an Fe-2.2 wt.% Si grain boundary, since they exhibit a distinct strain burst that is related to the presence of the boundary. It is possible, therefore, to fit the theoretically determined analytical expression for the interfacial yield stress to the experimental data. From this fit, first estimates are obtained for key material parameters, namely the interfacial term and the internal length, that are required for the theoretical formulation. Dislocation mechanics are employed to provide physical insight of these parameters.

AB - In this paper, it is shown that the occurrence of dislocation pileups across grain boundaries, as well as subsequent emission to the adjacent grains, is captured theoretically by gradient plasticity and confirmed experimentally by nanoindentation. From a theoretical point of view, this is accomplished (within a deformation theory framework applicable to continued loading) by accounting for a specific interfacial term in the overall potential of the material, in terms of which its response, taken to conform to strain gradient plasticity, is defined. The main features that result from the addition of this interfacial term are (i) significant size effects of Hall-Petch type in the overall stress-strain response of polycrystals and (ii) the determination of an analytical expression for the stress corresponding to the onset of dislocation transfer across interfaces. From an experimental point of view, the effective stress at which dislocation transfer takes place across an interface can be obtained from nanoindentations performed in close proximity to an Fe-2.2 wt.% Si grain boundary, since they exhibit a distinct strain burst that is related to the presence of the boundary. It is possible, therefore, to fit the theoretically determined analytical expression for the interfacial yield stress to the experimental data. From this fit, first estimates are obtained for key material parameters, namely the interfacial term and the internal length, that are required for the theoretical formulation. Dislocation mechanics are employed to provide physical insight of these parameters.

KW - Dislocations

KW - Fe-Si bicrystal

KW - Grain boundary

KW - Nanoindentation

KW - Plasticity

UR - http://www.scopus.com/inward/record.url?scp=33750005837&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33750005837&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2006.06.040

DO - 10.1016/j.actamat.2006.06.040

M3 - Article

VL - 54

SP - 5077

EP - 5085

JO - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 19

ER -