TY - JOUR

T1 - The effect of size on the strength of FCC metals at elevated temperatures

T2 - annealed copper

AU - Wheeler, Jeffrey M.

AU - Kirchlechner, Christoph

AU - Micha, Jean-Sébastien

AU - Michler, Johann

AU - Kiener, Daniel

PY - 2016/12/1

Y1 - 2016/12/1

N2 - 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.

AB - 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.

KW - copper

KW - high temperature deformation

KW - Size effect

KW - µ-Laue diffraction

UR - http://www.scopus.com/inward/record.url?scp=84984670356&partnerID=8YFLogxK

U2 - 10.1080/14786435.2016.1224945

DO - 10.1080/14786435.2016.1224945

M3 - Article

AN - SCOPUS:84984670356

VL - 96.2016

SP - 3379

EP - 3395

JO - Philosophical magazine

JF - Philosophical magazine

SN - 1478-6435

IS - 32-34

ER -