Phd in Material Science : New recycling process for aluminum alloys

Background and objectives

To limit global warming, the European Union has committed to reduce its greenhouse gas (GHG) emissions by at least 40 % in 2030. To meet this ambitious goal, as any other sector, the one of metallic alloy production has to dramatically decrease its emissions. To do so, the development of new recycling methods is a promising approach. Currently, metallic alloys are recycled by re-melting, which already decreases very significantly the GHG emissions compared to the production from ores. To decrease them even more, the solid-state recycling relies on the direct extrusion of the alloys to be recycled.

Solid-state recycling has already been applied to an aluminum alloy and very promising mechanical properties were measured. However, a tendency to decohesion, induced by magnesium oxides, was also observed. Thus, there is an interaction between impurities coming from the process (as oxygen) and alloying elements (as magnesium), which modifies the microstructure and may degrade the mechanical properties.

Methodology and missions

The objective of this PhD thesis is to be able to predict, for several grades of aluminum alloys, the solid-state recycling conditions allowing to obtain mechanical properties as close as possible from the ones of the non-recycled alloy. To do so, a multi-scale approach combining simulation and experiments is proposed.

First, the oxidation kinetics, which were identified as the key parameter influencing the chips’ surface and, subsequently, their welding, will be studied both by modelling and experimentally, especially by XPS (X-ray Photoelectron Spectroscopy). The most favorable conditions for solid-state recycling, especially the temperature, will thus be identified and used to process alloys. Their microstructure and mechanical properties will be characterized in detail, thanks to scanning and transmission electron microscopy, nanoindentation and tensile tests. For the most promising extruded alloy, the precipitation kinetics will be studied by combining modelling and experiments. The comparison between the mechanical properties of the hardened extruded alloy and the same alloy, also hardened but not recycled, will highlight the application potential of solid-state recycling.

Alongside, the PhD student will be involved in a project of popularization of science, whose main communication support is the Instagram account o_mon_labo.

Interest of the project

This new recycling process is a meaningful project, whose aim is to deal with a major challenge of our society: the fight again global warming. This is also a great opportunity to acquire various skills: mastering of experimental and modelling tools, long term project management, communication towards experts as well as popularization of science. Finally, this is a collaborative project between several research teams, including abroad. 

Practical informations

The PhD will take place in the Institute of Chemistry and Materials Paris East (Thiais) and the Institute of Research of Chemistry Paristech (Paris). Stays in Dortmund University (Germany) are planned. The PhD will be under the direction of Mathilde Laurent-Brocq and supervised by Lola Lilensten. The beginning will be on the 1st of October 2022, for a duration of 3 years.

Candidate profil 

  • Engineer or master 2 degree with a specialization in materials science (or metallurgy) and a path of excellence
  • Interest in experimental and modelling work, autonomy, rigor, initiative.
  • High level of English (writen and spoken). Some knowledge of German is a plus.

To apply, send a CV, a letter of motivation, a school transcript for master and/or engineer degree as well as two references (internship or project supervisors) to

Application deadline: 15th of April 2022

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