Abstract
Nanoporous gold has many potential applications in various fields, including energy storage, catalysis, sensing and actuating. Dealloying of Ag-Au alloys under free corrosion conditions is a simple method to fabricate nanoporous gold. Here, we systematically investigate the dealloying rate of Ag-xAu alloy for a range of alloy compositions (x = 20-40 at.%) and nitric acid concentration (7.3-14.9 M) using in situ transmission X-ray microscopy. High-resolution in situ X-ray projections and ex situ tomographic reconstructions allow imaging of the dealloying front position during dealloying. The dealloying front velocity is constant with time, and depends exponentially on the alloy Ag/Au atomic ratio and the acid molar concentration. Only the leanest alloy, Ag-20 Au, shows a large macroscopic shrinkage in sample diameter (∼38%) after dealloying, which leads to crack nucleation and growth observed in real time during dealloying. Finite element modeling is used to estimate dealloying-induced stresses and strains, and sheds light on the cracks created by the diameter shrinkage.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5561-5570 |
| Number of pages | 10 |
| Journal | Acta Materialia |
| Volume | 61 |
| Issue number | 15 |
| DOIs | |
| State | Published - Sep 2013 |
Funding
We gratefully thank Prof. Peter Voorhees (NU) for useful discussions throughout the experimental design and data analysis and Mr. Alex Deriy (APS) who helped with the in situ dealloying setup. X-ray imaging was assisted by Dr. Alix Deymier-Black (NU), Ms. Rachel Mak (NU) and Mr. Ashish Tripathi (U Melbourne). Use of the APS is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Keywords
- In situ
- Nanofoam
- TXM
- X-ray imaging
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys