Journal
ACTA MATERIALIA
Volume 57, Issue 9, Pages 2665-2672Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2009.02.017
Keywords
Nanoporous; Dealloying; Plastic deformation; Compression test; Hardness test
Funding
- Alexander von Humboldt foundation
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Nanoporous metals prepared by alloy corrosion may assume the form of monolithic, millimeter-sized bodies containing around 10(15) nanoscale ligaments per cubic millimeter. Here, we report on the fabrication and mechanical behavior of macroscopic, crack-free nanoporous gold samples which exhibit excellent ductility in compression tests. Their yield stress is significantly lower than that expected based on scaling laws or on previous nanoindentation experiments. Electron backscatter diffraction imaging reveals a polycrystalline microstructure with grains larger than 10 mu m which acquire a subdomain structure during plastic flow, but remain otherwise intact. We highlight the action of lattice dislocations which can travel over distances much larger than the ligament size. This results in a collective deformation of the many ligaments in each grain. Remarkably, the dislocation cores are partly located in the pore channels. The results suggest a critical view of the conversion between indentation hardness and yield stress in previous work. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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