This article is cited in 4 papers

Mechanical properties, strength physics and plasticity

Surface size effects under plastic deformation of microcrystals and nanocrystals

G. A. Malygin

Ioffe Institute, St. Petersburg

Abstract: The size effects associated with the crystal surface as an effective sink for moving dislocations in a thin crystal and as a barrier for these dislocations in the presence of a high-strength film or a special hardened layer on the surface, which favor the accumulation of dislocations in the crystal, have been considered theoretically in terms of the kinetic equation for the density of dislocations concentrated in the crystal in the critical lengths of single-ended (unipolar) dislocation sources. The theoretical results have been illustrated by the experimental data available in the literature for microcrystals and nanocrystals of copper and aluminum. It has been found in accordance with these data that the dependence of the yield stress $\sigma_{2\%}$ of the crystal on the crystal transverse size $D$ has the form $\sigma_{2\%}\sim D^{-0.75}$ when there is a free crystal surface for the escape ofthe dislocations and $\sigma_{2\%}\sim D^{-0.5}$ when there is a high-strength layer on the lateral surface of the crystal.

Received: 18.01.2012

 English version: Physics of the Solid State, 2012, 54:8, 1606–1611

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