The effect of size on the strength of FCC metals at elevated temperatures: annealed copper

Jeffrey M. Wheeler, Christoph Kirchlechner, Jean-Sébastien Micha, Johann Michler, Daniel Kiener

Research output: Contribution to journalArticleResearchpeer-review

20 Citations (Scopus)

Abstract

As the length scale of sample dimensions is reduced to the micron and sub-micron scales, the strength of various materials has been observed to increase with decreasing size, a fact commonly referred to as the ‘sample size effect’. In this work, the influence of temperature on the sample size effect in copper is investigated using in situ microcompression testing at 25, 200 and 400 °C in the SEM on vacuum-annealed copper structures, and the resulting deformed structures were analysed using X-ray μLaue diffraction and scanning electron microscopy. For pillars with sizes between 0.4 and 4 μm, the size effect was measured to be constant with temperature, within the measurement precision, up to half of the melting point of copper. It is expected that the size effect will remain constant with temperature until diffusion-controlled dislocation motion becomes significant at higher temperatures and/or lower strain rates. Furthermore, the annealing treatment of the copper micropillars produced structures which yielded at stresses three times greater than their un-annealed, FIB-machined counterparts.
Original languageEnglish
Pages (from-to)3379-3395
Number of pages17
JournalPhilosophical magazine
Volume96.2016
Issue number32-34
DOIs
Publication statusPublished - 1 Dec 2016

Keywords

  • copper
  • high temperature deformation
  • Size effect
  • µ-Laue diffraction

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