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

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

*Corresponding author for this work

Research output: Contribution to journalArticle

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.

Original languageEnglish
Pages (from-to)2547-2563
Number of pages17
JournalPhilosophical Magazine
Volume96
Issue number24
Early online date21 Jul 2016
DOIs
Publication statusPublished - 22 Aug 2016

Bibliographical note

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

Keywords

  • indentation creep
  • Nanoindentation
  • viscoplasticity
  • zirconium alloy

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