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How calcium prevents precipitation hardening in Al–Mg–Si alloys

Abstract

We have investigated the effect on precipitate microstructure and hardness upon adding small amounts of Ca to a base Al–Mg–Si alloy. The main investigative techniques were transmission and scanning electron microscopy. We found that large Ca-containing particles with composition CaAl2Si2 form during the production stages of the alloy. The particles leave less Si available in solid solution for the nucleation of hardening precipitates, leading to a coarser microstructure consisting of less coherent precipitates. The resulting hardness decrease is measurable for alloys containing more than 60 at ppm of Ca.

Category

Academic article

Client

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

Language

English

Affiliation

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

Year

2013

Published in

Materials Science & Engineering: A

ISSN

0921-5093

Publisher

Elsevier

Volume

575

Page(s)

241 - 247

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