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Length scales in alloy dissolution and measurement of absolute interfacial free energy

Nature Materials volume 5, pages 946949 (2006) | Download Citation

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Abstract

De-alloying is the selective dissolution of one or more of the elemental components of an alloy. In binary alloys that exhibit complete solid solubility, de-alloying of the less noble component results in the formation of nanoporous metals, a materials class that has attracted attention for applications such as catalysis1, sensing2 and actuation3. In addition, the occurrence of de-alloying in metallic alloy systems under stress is known to result in stress-corrosion cracking4, a key failure mechanism in fossil fuel and nuclear plants5, ageing aircraft6, and also an important concern in the design of nuclear-waste storage containers7. Central to the design of corrosion-resistant alloys is the identification of a composition-dependent electrochemical critical potential, Vcrit, above which the current rises dramatically with potential, signalling the onset of bulk de-alloying8,9. Below Vcrit, the surface is passivated by the accumulation of up to several monolayers of the more noble component. The current understanding of the processes that control Vcrit is incomplete. Here, we report on de-alloying results of Ag/Au superlattices that clarify the role of pre-existing length scales in alloy dissolution. Our data motivated us to re-analyse existing data on critical potentials of Ag–Au alloys and develop a simple unifying picture that accounts for the compositional dependence of solid-solution alloy critical potentials.

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Acknowledgements

This work was supported by the National Science Foundation (DMR-0301007 and CTS-0304062).

Author information

Affiliations

  1. Arizona State University, Tempe, Arizona 85287-6106, USA

    • J. Rugolo
    •  & K. Sieradzki
  2. Johns Hopkins University, Baltimore, Maryland 21218, USA

    • J. Erlebacher

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Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to K. Sieradzki.

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DOI

https://doi.org/10.1038/nmat1780

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