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The Effect of Zn on precipitation in Al-Mg-Si alloys

Abstract

Effects of addition of Zn (up to 1 wt%) on microstructure, precipitate structure and intergranular corrosion (IGC) in an Al–Mg–Si alloys were investigated. During ageing at 185 °C, the alloys showed modest increases in hardness as function of Zn content, corresponding to increased number densities of needle-shaped precipitates in the Al–Mg–Si alloy system. No precipitates of the Al–Zn–Mg alloy system were found. Using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), the Zn atoms were incorporated in the precipitate structures at different atomic sites with various atomic column occupancies. Zn atoms segregated along grain boundaries, forming continuous film. It correlates to high IGC susceptibility when Zn concentration is ~1wt% and the materials in peak-aged condition.

Category

Academic article

Client

  • Research Council of Norway (RCN) / 197405
  • Research Council of Norway (RCN) / 193619

Language

English

Author(s)

Affiliation

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

Year

2014

Published in

Philosophical Magazine

ISSN

1478-6435

Volume

94

Issue

21

Page(s)

2410 - 2425

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