Avalanche Dynamics and the Effect of Straining in Dislocation Systems with Quenched Disorder
arxiv(2024)
摘要
The plastic deformation of crystalline and other heterogeneous materials
often manifests in stochastic intermittent events indicating the criticality of
plastic behavior. Previous studies demonstrated that the presence of
short-ranged quenched disorder modifies this behavior disrupting long-range
static and dynamic correlations consequently localizing dislocation avalanches.
However, these observations were mostly confined to relaxed materials devoid of
deformation history. In this work our focus is on how straining affects static
and dynamic correlations, avalanche dynamics and local yield stresses. We
demonstrate that the interplay between severe straining and confining quenched
disorder induces critical behavior characterized by dislocation avalanches
distinct from those at lower stresses. Namely, near the flow stress many
avalanches, even if triggered locally, evolve into events affecting a larger
region by exciting small clusters of dislocations all around the sample. This
type of avalanches differ from the ones at low strains where plastic events
typically consist of one compact cluster of dislocations which is either local
or it is already quite extended at the onset of the avalanche. Furthermore, we
examine the impact of avalanches on local yield stresses. It is shown in detail
in this work that while some statistical features of the local yield thresholds
are robust to straining, others are significantly affected by the deformation
history.
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