Low Temperature Physics: 42, 825 (2016); https://doi.org/10.1063/1.4964325
Fizika Nizkikh Temperatur: Volume 42, Number 9 (September 2016), p. 1053-1066    ( to contents , go back )

The plastic deformation mechanisms of ultra fine-grained copper at temperatures 4.2–300 K

N.V. Isaev1, T.V. Grigorova1, O.V. Mendiuk2, O.A. Davydenko3, S.S. Polishchuk4, and V.G. Geidarov1

1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Pr. Nauky, Kharkiv 61103, Ukraine
E-mail: isaev@ilt.kharkov.ua

2Institute of Low Temperature and Structure Researches, Polish Academy of Science, 2 ul. Okólna, Wrocław, 50-422, Poland

3O.O. Galkin Donetsk Institute for Physics and Engineering NAS of Ukraine, Kyiv 03680, Ukraine

4G.V. Kurdyumov Institute for Metal Physics National of the Sciences of Ukraine 36 Academician Vernadsky Blvd., UA-03680, Kiev-142, Ukraine

Received April 22, 2016

Abstract

The main microstructure features of UFG Cu–OF polycrystals processed by direct and equal-channel angular hydroextrusion were studied by EBSD and XRD methods. The effect of microstructure on the temperature dependencies of yield stress and strain rate stress sensitivity of polycrystals was investigated at tension and stress relaxation tests in the insufficiently explored temperature range of 4.2–300 K. From the thermally activated analysis the forest intersection mechanism was determined as rate controlling of plastic deformation in the range 77–200 K and its empirical parameters were obtained. The experimental anomalies below 77 K as deviations from thermally activated intersection process were explained by inertial dislocation properties revealed at high effective stress and low dynamic friction of dislocations. The inverse temperature dependencies of activation volume revealed above 200 K were attributed to the thermally activated grain boundary dislocation depining relevant for UFG structure.

PACS: 61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.);
PACS: 62.20.F– Deformation and plasticity;
PACS: 62.20.–x Mechanical properties of solids;
PACS: 81.40.Lm Deformation, plasticity, and creep.

Key words: Ultrafine grained materials, copper, dislocations, thermally activated deformation Yield strength, Activation volume, low temperature, anomalies.

Published online: July 25, 2016

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