Vapor phase dealloying kinetics of MnZn alloys

Zhen Lu, Fan Zhang, Daixiu Wei, Jiuhui Han, Yanjie Xia, Jing Jiang, Mingwang Zhong, Akihiko Hirata, Kentaro Watanabe, Alain Karma, Jonah Erlebacher, Mingwei Chen

Research output: Contribution to journalArticlepeer-review

Abstract

Vapor phase dealloying (VPD) is an environmentally-friendly method for fabricating nanoporous materials by utilizing the saturated vapor pressure difference of elements to selectively drive sublimation of one or more components from an alloy. VPD kinetics has not been explored and rate-controlling factors of the solid-gas transformation within complex nanostructure remain unknown. Using manganese-zinc alloys as a prototype system, we systematically investigated the dependence of dealloying velocity on temperature and pressure and presented a model to quantitatively describe the dealloying kinetics. We found that the dealloying velocity exhibits a linear to power law transition at a critical dealloying depth, resulting from the interplay between the kinetic process of dealloying and dealloyed microstructure. This transition bridges ballistic evaporation at early time to Knudsen diffusion of Zn vapor in developed pore channels where the Zn partial pressure at the dealloying front reaches the local equilibrium between the solid and vapor phases. By comparing activation energies for VPD and bulk zinc sublimation, the entire energy landscape of VPD is measured. The fundamental understanding of VPD kinetics paves an effective way to design dealloyable precursor alloys and to optimize dealloyed microstructure of VPD materials for a wide range of applications.

Original languageEnglish
Article number116916
JournalActa Materialia
Volume212
DOIs
Publication statusPublished - 2021 Jun 15

Keywords

  • Activation energy
  • Ballistic evaporation
  • Dealloying kinetics
  • Knudsen diffusion
  • Vapor phase dealloying

ASJC Scopus subject areas

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

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