https://doi.org/10.1140/epjb/e2008-00198-5
Material yielding and irreversible deformation mediated by dislocation motion
1
Departament de Física Fonamental, Facultat de Física,
Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
2
Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, 02015 HUT, Finland
Corresponding author: a carmen.miguel@ub.edu
Received:
30
November
2007
Revised:
28
March
2008
Published online:
21
May
2008
We study the collective behavior of dislocation assemblies in
simplified models of plastic deformation. We first review several
numerical results on long range dislocation interactions with
simplified dislocation motion constraints. These typically
give rise to a yielding transition separating
stationary and moving dislocation phases. Furthermore, we discuss the
intermittent relaxation of the plastic strain-rate observed around
this transition at mesoscopic scales, and how this intermittent
behavior gives rise to an average slow power law relaxation in time
known in the literature as Andrade's creep. We analyze the coherent
dynamics and the average stress-strain
relationship in the steady regime of plastic
deformation. In this steady regime, plastic deformation proceeds in
the form of plastic avalanches whose size and duration are broadly
distributed and statistically characterized. One signature of the
time correlations of this heterogeneous collective dislocation
dynamics is a power spectrum scaling with
frequency as with an exponent α close to 1.5.
This feature appears to be peculiar of dislocation and grain boundary
motion as has been observed in other physical situations in the vicinity of a yielding transition.
PACS: 62.20.-x – Mechanical properties of solids / 62.20.Fe – Deformation and plasticity
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008