Hydrogen-induced strain localisation in oxygen-free copper in the initial stage of plastic deformation

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Abstract

Single crystals of oxygen-free copper oriented to easy glide of dislocations were tensile tested in order to study the hydrogen effects on the strain localisation in the form of slip bands appearing on the polished specimen surface under tensile straining. It was found that hydrogen increases the plastic flow stress in Stage I of deformation. The dislocation slip localisation in the form of slip bands was observed and analysed using an online optical monitoring system and atomic force microscopy. The fine structure of the slip bands observed with AFM shows that they consist of a number of dislocation slip offsets which spacing in the presence of hydrogen is markedly reduced as compared to that in the hydrogen-free specimens. The tensile tests and AFM observations were accompanied with positron annihilation lifetime measurements showing that straining of pure copper in the presence of hydrogen results in free volume generation in the form of vacancy complexes. Hydrogen-enhanced free-volume generation is discussed in terms of hydrogen interactions with edge dislocation dipoles forming in double cross-slip of screw dislocations in the initial stage of plastic deformation of pure copper.

Details

Original languageEnglish
Pages (from-to)727-740
Number of pages14
JournalPhilosophical Magazine
Volume98
Issue number9
Early online date22 Dec 2017
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • Copper, hydrogen in metals, positron annihilation, slip bands, vacancies

ID: 17194506