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Title: Correlations between the instantaneous velocity gradient and the evolution of scale-to-scale fluxes in two-dimensional flow
Authors:
;
Publication Date:
NSF-PAR ID:
10011433
Journal Name:
Physical Review E
Volume:
92
Issue:
3
ISSN:
1539-3755
Publisher:
American Physical Society
Sponsoring Org:
National Science Foundation
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  1. Nanoindentation and microcrystal deformation are two methods that allow probing size effects in crystal plasticity. In many cases of microcrystal deformation, scale-free and potentially universal intermittency of event sizes during plastic flow has been revealed, whereas nanoindentation has been mainly used to assess the stress statistics of the first pop-in. Here, we show that both methods of deformation exhibit fundamentally different event-size statistics obtained from plastic instabilities. Nanoindentation results in scale-dependent intermittent microplasticity best described by Weibull statistics (stress and magnitude of the first pop-in) and lognormal statistics (magnitude of higher-order pop-ins). In contrast, finite-volume microcrystal deformation of the same material exhibits microplastic event-size intermittency of truncated power-law type even when the same plastic volume as in nanoindentation is probed. Furthermore, we successfully test a previously proposed extreme-value statistics model that relates the average first critical stress to the shape and scale parameter of the underlying Weibull distribution.