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HAADF-STEM and DFT investigations of the Zn-containing β'' phase in Al-Mg-Si alloys

Abstract

The Zn-containing β″ phase in Al–Mg–Si alloys was investigated by aberration corrected high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), combined with density functional theory (DFT) calculations. The mean intensity of one Si site of the β″ phase is higher than that of the other Si sites, suggesting partial Zn occupancy. DFT studies support that this Si site is competitive for Zn incorporation. While HAADF-STEM image simulations show an influence of the Zn distribution along the β″ main growth direction, total energy calculations predict a weak Zn–Zn interaction. This suggests that Zn atoms are not clustering, but uniformly distributed along the atomic columns. The Zn incorporation has a weak influence on the β″ phase, where Zn is admitted as a “defect” according to the DFT studies.

Category

Academic article

Client

  • Research Council of Norway (RCN) / 193619
  • NORTEM / 197405
  • Notur/NorStore / NN8068K

Language

English

Author(s)

Affiliation

  • Norwegian University of Science and Technology
  • University of Rouen Normandy
  • SINTEF Industry / Materials and Nanotechnology

Year

2014

Published in

Acta Materialia

ISSN

1359-6454

Publisher

Pergamon Press

Volume

78

Page(s)

245 - 253

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