Fizika Nizkikh Temperatur: Volume 43, Number 12 (December 2017), p. 1789-1795    ( to contents , go back )

Anisotropy of the yield strength and structural parameters of nanocrystalline titanium obtained by cryodeformation

V.A. Moskalenko, Yu.M. Pohribnaya, R.V. Smolianets, and I.S. Braude

B. Verkin Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103, Ukraine
E-mail: moskalenko@ilt.kharkov.ua

Received Jule 11, 2017, revised August 1, 2017

Abstract

Anisotropy of the yield strength of nanocrystalline commercial purity titanium with grain size ~ 45 nm, obtained by the cryomechanical grain fragmentation method, is studied. The experiments in the temperature range 4.2−300 K in the uniaxial compression regime at a nominal plastic deformation rate of 3.5⋅10–4 s−1 was carried out. The temperature dependences of the macroscopic yield strength of the samples with the compression axis along and transverse direction of cryorolling has been obtained. The coefficient of anisotropy of the yield strength is calculated and its temperature dependence is established. The parameter’s values of the deformation microstructure in orthogonally planes were determined: the dimensions of the crystallites (coherent scattering region) and the values of microdeformations. Morphological anisotropy of crystals was detected. Compatibility between the calculated and experimental values of the yield strength of the samples deformed in orthogonally direction of the cryorolling, the Hall–Petch ratio, and the detected sizes of the crystallites were found to be in agreement with the calculated values. The anisotropy of the yield strength of nanocrystalline titanium is related to the anisotropy of the shape of such structural elements as grain/crystallite is shown.

PACS: 62.20.–x Mechanical properties of solids;
PACS: 61.46.–w Structure of nanoscale materials;
PACS: 81.07.–b Nanoscale materials and structures: fabrication and characterization.

Key words: nanocrystalline titanium, anisotropy of the yield strength, morphological anisotropy of crystals.

Published online: October 25, 2017

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