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Microstructures de précipitation et mécanismes de corrosion feuilletante dans les alliages d'aluminium de la série 7000 à très hautes caractéristiques mécaniques

Abstract : High strength 7XXX series aluminium alloys, composed of the major alloying elements Zn, Mg, and Cu, are used especially for aircraft applications. However, the ageing process, maximizing the mechanical properties, returns alloys sensitive to structural corrosion, and particularly to exfoliation corrosion. New developments in high strength alloys, for strength optimization, lead an overall increase in solute saturation, which could modify their corrosion susceptibility.
The objective of the study is to progress in the understanding of the exfoliation corrosion mechanisms of high-strength 7000 series aluminium alloys, by attempting especially to identify the role of the main alloying elements. By leaning on a quantitative precipitation characterisation of a large number of microstructures, we notably measured the composition of nanometric hardening precipitates and of the matrix, by ASAXS and 3DAP. In parallel, we developed new electrochemical techniques providing quantitative results on the exfoliation corrosion sensitivity of microstructures.
Theses results show the existence of two operating corrosion mechanisms: damages by " intergranular dissolution " and by intergranular ruptures. The ascendancy of which depends on the composition of the alloy.
We propose an explanation of the corrosion susceptibility of the various microstructures, based on the chemical composition of the microstructural entities and of the alloy.
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Contributor : Thorsten Marlaud <>
Submitted on : Wednesday, May 28, 2008 - 5:31:59 PM
Last modification on : Thursday, November 19, 2020 - 3:54:16 PM
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Thorsten Marlaud. Microstructures de précipitation et mécanismes de corrosion feuilletante dans les alliages d'aluminium de la série 7000 à très hautes caractéristiques mécaniques. Matériaux. Institut National Polytechnique de Grenoble - INPG, 2008. Français. ⟨tel-00282987⟩

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