Centre d’Élaboration de Matériaux et d’Etudes Structurales


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Ancient aluminum alloys

This theme focuses on the study of ancient aluminum alloys for aeronautics through an approach coupling laboratory analysis and archival research. The corpus is comprised of parts from aircrafts restored by Les Ailes Anciennes de Toulouse association in Blagnac (Fig. 1a) and from crashed aircrafts (mainly from World War II) excavated by the Aérocherche association (Fig. 1b).

Figure 1.a. Breguet 765 Sahara (1958) being renovated by Ailes Anciennes Toulouse

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Figure 1.b. Fragment of a fuselage of a Dornier 217 (1943) excavated by
the association Aérocherche

 The physicochemical nature and the structure of the crystalline phases, as well as their organization at different scales, are studied by combining various analytical techniques : electron microscopy (scanning, transmission) and associated spectroscopy (EDX, EELS), Raman spectroscopy, X-ray diffraction methods (Fig. 2 and 3). The analyses concern both healthy and altered metal as well as coatings (primers and paints).

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Figure 2. Multi-scale observations on aluminium alloys : analyses SEM and TEM

Figure 3. STEM Bright-field image of Duralumin alloy (1958) in [112]Al zone axis showing θ’-Al2Cu platelets (black arrows) and -Al2Cu rods (white arrows) growing
 
on dispersoids (AlMnS) ; b) HAADF image of -Al2Cu platelet 
(Images UMS Centre Raimond Castaing).

 

The goals of these analyses are :
- From a fundamental point of view, enhancing the understanding of the physical mechanisms involved in the aging of materials and material-properties relations in these complex, heterogeneous environments.
- Establishing the links between the physicochemical nature of the alloys, the conditions of exposure and the types of observed alterations. This information is essential for the development of practical conservation methods for Cultural Heritage objects : in this case to prevent corrosion of aircraft materials.
- Documenting materials, their manufacturing and beyond, with a historical point of view, so as to uncover the evolution of aluminum alloys at a time when the aeronautic industry developed significantly. Testimony of volunteers, archives from industrials, technical and scientific documents provide valuable information about the history of aircraft and constituent materials.

 PhD theses – codirection : CEMES-CNRS / FRAMESPA – University Toulouse Jean-Jaurès :

 - Audrey Cochard, Microstructures et propriétés mécaniques des alliages de type Duralumin du Breguet 765 n°5004 64-PH, approche historique et sciences des matériaux. PhD - University of Toulouse (2016).

- Toufa Ouissi, Etude des premiers alliages aéronautiques de type Duralumin au service de l’aviation militaire entre 1930 et 1945. Approche historique et métallographique, PhD - University of Toulouse (2016) (2021).

 

Projects :

 - StelAir (2016-2019) – Project EUR NanoX :

Coordination : CEMES- Team M3 ; Partners : CEMES- Team PPM ; CIRIMAT-ENSIACET.

 This project is focused on addressing the issue of long-term aging of Al-Cu alloys, based on the examination of materials from old aircrafts. Various laboratory analyses were used to characterize the composition and nanostructure of the selected, naturally aged alloys. The aim was to determine the structural evolution of light alloys over very long periods of time and the correlation with their mechanical behavior.

- PROCRAFT (2020-2023) – European project JPI-CH :

https://grand-patrimoine.loire-atlantique.fr/jcms/navigation/les-services/arc-antique/projet-procraft-fr-p2_324372

Coordination : Arc Antiques (Nantes) ; Partners : CEMES- Team M3 ; TRACES ; University of Bologna (Italy) ; University of Ferrara (Italy) ; CTU (Czech Republic)

Associated Partners : Museums, associations, local communities.

The main objective of the project is to propose protocols and solutions for each key stage in the conservation of aeronautical heritage objects :

- Adjusted conservation-restoration techniques

- Coatings for outdoor protection

- Preventive conservation solutions for hangar-type environments

- Procedures for non-professionals dealing with this kind of heritage (typically associations).

The project focuses on Second World War wrecks, which are being treated here as archaeological objects. The project is expected to generate a better knowledge of the technologies (aluminum metallurgy and coatings) of that era, improve conservation and allow dissemination and presentation to the public.

 

Recent articles :

2020

  1. M. Brunet, A. Cochard, C. Deshayes, C. Brouca-Cabarrecq, L. Robbiola, J.-M. Olivier, Ph. Sciau Study of Post-World War II French Aeronautical Aluminium Alloy and Coatings : Historical and Materials Science Approach. Studies in Conservation, Vol.65, Issue 2, p.103-117, 2020.
  2. M. Brunet, B. Malard, N. Ratel-Ramond, Ch. Deshayes, B. Warot-Fonrose, Ph. Sciau and J. Douin, Comparison of long-term natural aging to artificial aging in Duralumin, Proceedings of the 17th Conference on Aluminum Alloys, ICAA17, MATEC Web Conf., Volume 326 (2020) 04007.

 2019

  1. T. Ouissi, G. Collaveri, Ph. Sciau, J-M. Olivier and M. Brunet, Comparison of aluminum alloys from aircraft of four nations involved in the WWII conflict using multiscale analyses and archival study, Heritage, 2019, vol 2, Issue 4.
  2. M. Brunet, B. Malard, N. Ratel-Ramond, Ch. Deshayes, S. Joulié, B. Warot-Fonrose, Ph. Sciau, J. Douin, F. De Geuser, A. Deschamps, Precipitation in original Duralumin A-U4G versus modern 2017A alloy, Materialia, 2019, 8, pp.100429.

2017

  1. A. Cochard, K. Zhu, S. Joulié, J. Douin, J. Huez, L. Robbiola, P. Sciau, M. Brunet, Natural aging on Al-Cu-Mg structural hardening alloys – Investigation of two historical duralumins for aeronautics, Materials Science and Engineering : A 690 (2017), p. 259-269

 

Contact : Magali Brunet

Photothèque