In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy

Yu Chen Karen Chen-Wiegart; Steve Wang; Wah Keat Lee; Ian McNulty; Peter W. Voorhees; David C. Dunand

doi:10.1016/j.actamat.2012.10.017

In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy

Yu Chen Karen Chen-Wiegart^*, Steve Wang, Wah Keat Lee, Ian McNulty, Peter W. Voorhees, David C. Dunand

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

47 Scopus citations

Abstract

The dealloying process is directly imaged, for the first time, by using transmission X-ray microscopy for the case of an Ag-30 at.% Au wire dealloyed under free corrosion in nitric acid. The propagation of a sharp dealloying front separating the alloy from nanoporous Au was observed by two-dimensional real-time in situ imaging at 30 nm resolution and measured in detail in three dimensions by an ex situ nanotomography technique at fixed time intervals. The rate of the dealloying front propagation is independent of the dealloying time up to a 3 μm depth, indicating that the dealloying process to this depth is dominated by interfacial effects (i.e. gold surface diffusion and/or silver dissolution) rather than long-range transport effects (i.e. diffusion of acid and corrosion product in and out of the porous layer). The constant dealloying rate corresponds to a constant silver flux and a constant current density, even though the potential might be fluctuating under free corrosion conditions and the interfacial area is shrinking as a function of time. Free corrosion in this system generates a high current density, implying it is driven by a chemical potential difference that is much higher than the critical potential.

Original language	English (US)
Pages (from-to)	1118-1125
Number of pages	8
Journal	Acta Materialia
Volume	61
Issue number	4
DOIs	https://doi.org/10.1016/j.actamat.2012.10.017
State	Published - Feb 2013

Funding

We thank Prof. J. Erlebacher (Johns Hopkins University) for helpful discussions and Mr. B. Myers (Electron Probe Instrumentation Center, Northwestern University) for assistance with the sample preparation. We acknowledge assistance with the in situ experimental set-up from Drs. R. Harder and A. Deriy (APS) and with the TXM measurements from Ms. A. Deymier and A. Singhal (Northwestern University). We also thank Drs. Q. Shen and Y. Chu (Brookhaven National Laboratory) for advising the early stage of this project, and Prof. Y. Hwu (Academic Sinica) for developing the TXM instrument and making it available at APS. Use of the APS is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Keywords

Metal foam
TXM
X-ray synchrotron radiation

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

Access to Document

10.1016/j.actamat.2012.10.017

Cite this

@article{42260bcb0fa24e70971a0ea4dbc4b3a6,

title = "In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy",

abstract = "The dealloying process is directly imaged, for the first time, by using transmission X-ray microscopy for the case of an Ag-30 at.% Au wire dealloyed under free corrosion in nitric acid. The propagation of a sharp dealloying front separating the alloy from nanoporous Au was observed by two-dimensional real-time in situ imaging at 30 nm resolution and measured in detail in three dimensions by an ex situ nanotomography technique at fixed time intervals. The rate of the dealloying front propagation is independent of the dealloying time up to a 3 μm depth, indicating that the dealloying process to this depth is dominated by interfacial effects (i.e. gold surface diffusion and/or silver dissolution) rather than long-range transport effects (i.e. diffusion of acid and corrosion product in and out of the porous layer). The constant dealloying rate corresponds to a constant silver flux and a constant current density, even though the potential might be fluctuating under free corrosion conditions and the interfacial area is shrinking as a function of time. Free corrosion in this system generates a high current density, implying it is driven by a chemical potential difference that is much higher than the critical potential.",

keywords = "Metal foam, TXM, X-ray synchrotron radiation",

author = "Chen-Wiegart, {Yu Chen Karen} and Steve Wang and Lee, {Wah Keat} and Ian McNulty and Voorhees, {Peter W.} and Dunand, {David C.}",

note = "Funding Information: We thank Prof. J. Erlebacher (Johns Hopkins University) for helpful discussions and Mr. B. Myers (Electron Probe Instrumentation Center, Northwestern University) for assistance with the sample preparation. We acknowledge assistance with the in situ experimental set-up from Drs. R. Harder and A. Deriy (APS) and with the TXM measurements from Ms. A. Deymier and A. Singhal (Northwestern University). We also thank Drs. Q. Shen and Y. Chu (Brookhaven National Laboratory) for advising the early stage of this project, and Prof. Y. Hwu (Academic Sinica) for developing the TXM instrument and making it available at APS. Use of the APS is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. ",

year = "2013",

month = feb,

doi = "10.1016/j.actamat.2012.10.017",

language = "English (US)",

volume = "61",

pages = "1118--1125",

journal = "Acta Materialia",

issn = "1359-6454",

publisher = "Elsevier Limited",

number = "4",

}

TY - JOUR

T1 - In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy

AU - Chen-Wiegart, Yu Chen Karen

AU - Wang, Steve

AU - Lee, Wah Keat

AU - McNulty, Ian

AU - Voorhees, Peter W.

AU - Dunand, David C.

N1 - Funding Information: We thank Prof. J. Erlebacher (Johns Hopkins University) for helpful discussions and Mr. B. Myers (Electron Probe Instrumentation Center, Northwestern University) for assistance with the sample preparation. We acknowledge assistance with the in situ experimental set-up from Drs. R. Harder and A. Deriy (APS) and with the TXM measurements from Ms. A. Deymier and A. Singhal (Northwestern University). We also thank Drs. Q. Shen and Y. Chu (Brookhaven National Laboratory) for advising the early stage of this project, and Prof. Y. Hwu (Academic Sinica) for developing the TXM instrument and making it available at APS. Use of the APS is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

PY - 2013/2

Y1 - 2013/2

N2 - The dealloying process is directly imaged, for the first time, by using transmission X-ray microscopy for the case of an Ag-30 at.% Au wire dealloyed under free corrosion in nitric acid. The propagation of a sharp dealloying front separating the alloy from nanoporous Au was observed by two-dimensional real-time in situ imaging at 30 nm resolution and measured in detail in three dimensions by an ex situ nanotomography technique at fixed time intervals. The rate of the dealloying front propagation is independent of the dealloying time up to a 3 μm depth, indicating that the dealloying process to this depth is dominated by interfacial effects (i.e. gold surface diffusion and/or silver dissolution) rather than long-range transport effects (i.e. diffusion of acid and corrosion product in and out of the porous layer). The constant dealloying rate corresponds to a constant silver flux and a constant current density, even though the potential might be fluctuating under free corrosion conditions and the interfacial area is shrinking as a function of time. Free corrosion in this system generates a high current density, implying it is driven by a chemical potential difference that is much higher than the critical potential.

AB - The dealloying process is directly imaged, for the first time, by using transmission X-ray microscopy for the case of an Ag-30 at.% Au wire dealloyed under free corrosion in nitric acid. The propagation of a sharp dealloying front separating the alloy from nanoporous Au was observed by two-dimensional real-time in situ imaging at 30 nm resolution and measured in detail in three dimensions by an ex situ nanotomography technique at fixed time intervals. The rate of the dealloying front propagation is independent of the dealloying time up to a 3 μm depth, indicating that the dealloying process to this depth is dominated by interfacial effects (i.e. gold surface diffusion and/or silver dissolution) rather than long-range transport effects (i.e. diffusion of acid and corrosion product in and out of the porous layer). The constant dealloying rate corresponds to a constant silver flux and a constant current density, even though the potential might be fluctuating under free corrosion conditions and the interfacial area is shrinking as a function of time. Free corrosion in this system generates a high current density, implying it is driven by a chemical potential difference that is much higher than the critical potential.

KW - Metal foam

KW - TXM

KW - X-ray synchrotron radiation

UR - http://www.scopus.com/inward/record.url?scp=84873084104&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84873084104&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2012.10.017

DO - 10.1016/j.actamat.2012.10.017

M3 - Article

AN - SCOPUS:84873084104

SN - 1359-6454

VL - 61

SP - 1118

EP - 1125

JO - Acta Materialia

JF - Acta Materialia

IS - 4

ER -

In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy

Abstract

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this