title: The effect of size on the strength of FCC metals at elevated temperatures: annealed copper.
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 usingin situmicrocompression 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.
authors.affiliation: Laboratory for Nanometallurgy, ETH Zürich, Zurich, Switzerland; Laboratory for Mechanics of Materials and Nanostructures, Empa, Swiss Federal Laboratories for Materials Science and Technology, Thun, Switzerland.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Wheeler
authors.affiliation: Structure and Nano-/Micromechanics of Materials, Max-Planck-Institut fur Eisenforschung GmbH, Dusseldorf, Germany; Department of Materials Physics, Montanuniversität Leoben, Leoben, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kirchlechner
authors.affiliation: UMR CNRS-CEA SPrAM, Institute Nanosciences and Cryogenics, Université Grenoble Alpes, Grenoble, France; CRG-IF BM32 Beamline at the European Synchrotron (ESRF), Grenoble, France.
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Micha
authors.affiliation: Laboratory for Mechanics of Materials and Nanostructures, Empa, Swiss Federal Laboratories for Materials Science and Technology , Thun , Switzerland.
authors.forename: Johann
authors.initials: J
authors.lastname: Michler
authors.affiliation: Department of Materials Physics, Montanuniversität Leoben , Leoben , Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kiener
keywords: Size effect; copper; high temperature deformation; µ-Laue diffraction