Developing scaling relations for the yield strength of nanoporous gold

Abstract

In this work, the applicability of Gibson and Ashby’s porous scaling relations to nanoporous metals is discussed, and an updated equation is proposed for relating the yield strength of nanoporous gold to the yield strength of individual gold ligaments that form the porous structure. This new relation is derived from experimental measurements obtained by small-scale tensile testing and by nanoindentation, and incorporates the average ligament diameter. Nanoindentation data, obtained experimentally by the authors as well as reported by others in the literature, are reconciled with tensile test measurements previously reported by the present authors. The values of ligament yield strength calculated with the new scaling relation are found to agree with data reported from mechanical testing of nanowires, and the scaling relation thus represents a bridge between nanowire and nanoporous metal behaviour. In addition, calculations of yield strength for nanoporous gold samples with various ligament size and relative density are consistent with the experimentally determined values.

Keywords:

• scaling relation
• cellular material
• porous
• gold
• dealloying
• mechanical behaviour
• small-scale testing

Acknowledgements

The authors would like to thank T. Kennerknecht and C. Eberl, who helped perform the millimetre-scale tensile tests, as well as D. Gianola, for productive discussions about nanowire testing. The authors acknowledge support of the Electron Microscopy Center at the University of Kentucky.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This material is based upon work supported by the National Science Foundation [grant number DMR-0847693].