Experimental study of room-temperature indentation viscoplastic ‘creep’ in zirconium

S. C. Storer, Michael E. Fitzpatrick, S. V. Hainsworth, M. A. Rist

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Abstract

In this paper we have studied the mechanisms of so-called ‘indentation creep’ in a zirconium alloy. Nanoindentation was used to obtain strain rate data as the sample was indented at room temperature, at a homologous temperature below that for which creep behaviour would be expected for this material. A high value of strain rate was obtained, consistent with previous work on indentation creep. In order to elucidate the mechanism of time-dependent deformation, a load relaxation experiment was performed by uniaxial loading of a sample of the same alloy. By allowing relaxation of the sample from a peak load in the tensile test machine, a similar stress exponent was obtained to that seen in the nanoindentation creep test. We conclude that for metals, at temperatures below that at which conventional creep will occur, nanoindentation ‘creep’ proceeds through deformation on active slip systems that were initiated by prior loading beyond the plastic limit. It is therefore more appropriate to describe it as a viscoplastic process, and not as creep deformation. Publisher Statement: This is an Accepted Manuscript of an article published by Taylor & Francis in Philosophical Magazine on 21 Jul 2016, available online: http://www.tandfonline.com/10.1080/14786435.2016.1209310
Original languageEnglish
Pages (from-to)2547-2563
JournalPhilosophical Magazine
Volume96
DOIs
Publication statusPublished - 21 Jul 2016

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nanoindentation
indentation
strain rate
room temperature
zirconium alloys
creep tests
tensile tests
slip
plastics
exponents
temperature
metals

Bibliographical note

This is an Accepted Manuscript of an article published by Taylor & Francis in Philosophical Magazine on 21 Jul 2016, available online: http://www.tandfonline.com/10.1080/14786435.2016.1209310

Keywords

  • Nanoindentation
  • indentation creep
  • viscoplasticity
  • zirconium alloy

Cite this

Experimental study of room-temperature indentation viscoplastic ‘creep’ in zirconium. / Storer, S. C.; Fitzpatrick, Michael E.; Hainsworth, S. V.; Rist, M. A.

In: Philosophical Magazine, Vol. 96, 21.07.2016, p. 2547-2563.

Research output: Contribution to journalArticle

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