The mechanism of morphogenesis in a phase-separating concentrated multicomponent alloy

Zugang Mao*, Chantal K. Sudbrack, Kevin E. Yoon, Georges Martin, David N. Seidman

*Corresponding author for this work

Research output: Contribution to journalArticle

118 Scopus citations

Abstract

What determines the morphology of a decomposing alloy? Besides the well-established effect of the nucleation barrier, we demonstrate that, in a concentrated multicomponent Ni(Al,Cr) alloy, the details of the diffusion mechanism strongly affect the kinetic pathway of precipitation. Our argument is based on the combined use of atomic-scale observations, using three-dimensional atom-probe tomography (3D APT), lattice kinetic Monte Carlo simulations and the theory of diffusion. By an optimized choice of thermodynamic and kinetic parameters, we first reproduce the 3D APT observations, in particular the early-stage transient occurrence of coagulated precipitates. We then modify the kinetic correlations among the atomic fluxes in the simulation, without altering the thermodynamic driving force for phase separation, by changing the vacancy-solute interactions, resulting in a suppression of coagulation. Such changes can only be quantitatively accounted for with non-zero values for the off-diagonal terms of the Onsager matrix, at variance with classical models.

Original languageEnglish (US)
Pages (from-to)210-216
Number of pages7
JournalNature materials
Volume6
Issue number3
DOIs
StatePublished - Mar 7 2007

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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