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Microstructural Investigation of the Deformation Zone below Nano-Indents in Copper
Published online by Cambridge University Press: 01 February 2011
Abstract
The deformation zone below nanoindents in copper single crystals with an <110>{111} orientation is investigated. Using a focused ion beam (FIB) system, cross-sections through the center of the indents were fabricated and subsequently analyzed by means of electron backscatter diffraction (EBSD) technique. Additionally, cross-sectional TEM foils were prepared and examined. Due to changes in the crystal orientation around and beneath the indentations, the plastically deformed zone can be visualized and related to the measured hardness values. Furthermore, the hardness data were analyzed using the Nix-Gao model where a linear relationship was found for H2 vs. 1/hc, but with different slopes for large and shallow indentations. The measured orientation maps indicate that this behavior is presumably caused by a change in the deformation mechanism. On the basis of possible dislocation arrangements, two models are suggested and compared to the experimental findings. The model presented for large imprints is based on dislocation pile-ups similar to the Hall-Petch effect, while the model for shallow indentations uses far-reaching dislocation loops to accommodate the shape change of the imprint.
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- Copyright © Materials Research Society 2008
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