Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5435938 | Acta Materialia | 2017 | 9 Pages |
We find that hardness of nanoporous gold (np-Au) measured by nanoindentation tends to increase with decreasing indentation depth, similar to the indentation size effect (ISE) in solid materials. While ISE in solid materials is attributed to a local increase in density of geometrically necessary dislocations (GNDs), the origin of ISE in np-Au has not been studied systematically. We prepare four np-Au samples with ligament sizes of 26, 73, 126, and 630Â nm by free corrosion dealloying and post heat treatments. For the normalized hardness (hardness/macroscopic hardness) vs normalized indentation depth (indentation depth/three times ligament size), we find that the ISE trends for three np-Au samples of ligament sizes 26, 73, and 127Â nm are almost identical, while an enhanced ISE is shown for np-Au with greatest ligament size, 630Â nm. We investigate ISE in np-Au based on nanomechanics model for nanoindentation on np-Au with a sharp indenter, uniaxial compression and pure shear testing for np-Au.
Graphical abstractDownload high-res image (251KB)Download full-size image