Anomalous mechanical characteristics of Au/Cu nanocomposite processed by Cu electroplating

Abstract

An Au/Cu nanocomposite is produced by electroplating Cu on a nanoporous Au, and its mechanical characteristics are investigated by hardness tests. The Au/Cu nanocomposite showed a lower hardness and a lower elastic modulus than the nanoporous Au. Furthermore, annealing caused the nanocomposite to harden twice. Large lattice strains in the Au lattice for the nanocomposite were observed by high-resolution transmission electron microscopy. Also, first-principle calculations showed that lattice strains induce the decreased elastic modulus. Therefore, both the inverse mixing behaviour and the hardening via annealing are suggested to be related to the large lattice strains.

Keywords:

• nanocomposite
• mechanical properties
• lattice strains
• transmission electron microscopy (TEM)
• first-principle calculations

Acknowledgements

The authors thank Prof. T. Yao (Kyoto Univ.) and Prof. T. Yabutsuka (Kyoto Univ.) for their assistance with SEM observation. Thanks are due to Prof. T. Hirato (Kyoto Univ.) for XRD measurement. The authors also thank Dr Y. Chino (National Institute of Advanced Industrial Science and Technology (AIST)) for preparation of starting alloys.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

M.H. is grateful for financial support from JSPS Grant-in-Aid for Young Scientists (B) 24760572 for preparation of nanoporous metals. M.M. is grateful for financial support from JSPS Grant-in-Aid for Scientific Research (B) 23360305 for TEM observation.