The mechanical response of core-shell structures for nanoporous metallic materials

Niaz Abdolrahim, David F. Bahr, Benjamin Revard, Cassandra Reilly, Jia Ye, T. John Balk, Hussein M. Zbib

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Nanoporous gold (NP-Au) exhibits microscale plasticity, but macroscopically fails in a relatively brittle manner. This current study suggests that a core-shell structure can increase both ductility and strength of NP-Au. A core Au foam structure was created using conventional dealloying methods with average ligament size of 60 nm. Nickel was then electroplated on to the NP-Au with layer thicknesses ranging from 2.5 nm to 25 nm. Nanoindentation demonstrated a significant increase in the hardness of the coated Np-Au, to about five times of that of the pure Np-Au, and a decrease in creep by increasing the thickness of the coated Ni layer. Molecular dynamics simulations of Au-Ni ligaments show the same trend of strengthening behavior with increasing Ni thickness suggesting that the strengthening mechanisms of the Np-Au are comparable to those for fcc nano ligaments. The simulations demonstrate two different strengthening mechanisms with the increased activity of the twins in plated Au-Ni ligaments, which leads to more ductile behavior, as opposing to the monolithic Au ligaments where nucleation of dislocations govern the plasticity during loading.

Original languageEnglish
Pages (from-to)736-748
Number of pages13
JournalPhilosophical Magazine
Volume93
Issue number7
DOIs
StatePublished - Mar 1 2013

Bibliographical note

Funding Information:
This work was supported at WSU by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences under grant no. DE-FG02-07ER46435. C. Reilly was supported by the National Science Foundation’s REU program under grant no. DMR-0755055. The work at UK is based upon work supported by the National Science Foundation under grant no. DMR-0847693.

Keywords

  • MD simulations
  • de-alloying
  • ductility
  • nanoindentation
  • nanoporous gold
  • strengthening mechanisms

ASJC Scopus subject areas

  • Condensed Matter Physics

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