Paper Title:

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

Periodical Materials Science Forum (Volumes 503 - 504)
Main Theme Nanomaterials by Severe Plastic Deformation
Edited by Zenji Horita
Pages 31-36
DOI 10.4028/www.scientific.net/MSF.503-504.31
Citation Johannes Mueller et al., 2006, Materials Science Forum, 503-504, 31
Online since January 2006
Authors Johannes Mueller, Karsten Durst, Dorothea Amberger, Matthias Göken
Keywords Nanocrystalline Metals, Nanoindentation, Pulsed Electrodeposition, Strain Rate Sensitivity (SRS), Ultra Fine Grained Metal
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The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.