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Design of solute clustering during thermomechanical processing of AA6016 Al–Mg–Si alloy.
- Source :
-
Acta Materialia . Jan2021, Vol. 203, pN.PAG-N.PAG. 1p. - Publication Year :
- 2021
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Abstract
- Solute clustering is a technologically important microstructural process in Al alloys. Exerting control over this process to enhance the alloy properties and reduce the energy costs of production is a major scientific and technological focus, with automotive sheet applications serving as a key driver. In this work, we detail changes in the state of clustering arising from the insertion of a thermomechanical pre-ageing process, via a coil-cooling step in a commercial production line, immediately after solution treatment. This pre-ageing step effectively mitigates the negative effects of the natural ageing on the mechanical properties that would otherwise occur after solution treatment and ahead of the final paint-bake step. Our work was focussed on a short duration/low temperature single-step pre-ageing process on a Cu-lean grade of AA6016. Using a combination of atom probe tomography and first principles density functional theory simulations, we are able to reveal and explain the atomic-scale microstructure arising from this thermomechanical process. Mg–Si co-clusters ≥ 20 solute atoms were found responsible for the excellent properties in the material exposed to the pre-ageing plus paint-baking process. Our simulations revealed that vacancies can effectively stabilise single-species Si clusters enabling them to attract further solute and serving as a pathway to formation of the larger Mg–Si co-clusters that are so beneficial to alloy properties. Our simulations also revealed that the nearest neighbour configurations are a critical aspect to the stability of the clusters. Image, graphical abstract [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 203
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 147650221
- Full Text :
- https://doi.org/10.1016/j.actamat.2020.10.074