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Processing of microporous metallic powders by liquid metal dealloying (H/F)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : jeudi 24 juin 2021

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General information

Reference : UMR5510-PIEGES-002
Date of publication : Thursday, June 3, 2021
Scientific Responsible name : Eric Maire
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Additive manufacturing processes such as robot-casting and cold-spray attract increasing attention because of their capability to fabricate new materials with improved mechanical and functional properties. To optimize these techniques, the control of the metallic powder's properties is crucial. In particular, the particles' composition, diameter, and mechanical properties are key parameters to obtain microstructures with desired properties. Nowadays, powders are obtained by classical metallurgical processes such as gaseous or aqueous atomization. These processes do not modify the porosity and the mechanical properties of the resulting powder, which can be a limiting issue.
This project aims to use the liquid metal dealloying technique to design micro-porous powders with controlled porosity. This porosity will modify the powder's mechanical properties and surface reactivity, two critical parameters for additive manufacturing techniques.

Micro-porous powders will be elaborated at IMR (Tohoku University, Sendai, Japan) with the support of ELyTMaX (CNRS/Tohouku University, Sendai, Japan). The former has a long experience in innovative elaboration techniques with developing the liquid metal dealloying technique in the past decade. Simultaneously, the latter will assist in characterizing the morphology of the dealloyed particles to relate the dealloying parameters (composition, time, temperature) to the morphology of the final powder particles. These experimental results will be compared to numerical models developed in the framework of the Elyt collaboration between Lyon and Tohoku University [1]. Simulations of the dealloying process and the subsequent coarsening mechanisms will establish the link between dealloying parameters and the resulting morphology.

Finally, advanced properties (3D porosity, hardness, surface electrochemical reactivity) will be quantified at MATEIS (INSA Lyon) using cutting-edge characterization methods such as X-ray tomography, allowing a detailed comparison of morphologies between experimental and simulation results. Both approaches will help understand the dealloying process of spherical particles and will enable to propose guidelines to optimize the dealloying parameters to obtain a microporous powder with controlled porosity and mechanical properties.
The synergy between the different projects partners - with materials elaboration performed at IMR (Tohoku University), characterization and numerical simulations performed at Mateis (INSA-Lyon) - has already been successfully applied previously in the framework of a PhD project under joint supervision focusing on the elaboration and characterization of micro-porous samples obtained with the liquid metal dealloying technique [2,3].

To carry out this PhD project, we are looking for a student with the following profile:
• Engineering school and/or Master with a focus on materials science.
• Good knowledge in metallurgy is necessary.
• Basic skills in programming and numerical tools will be considered as a plus for the project.
• Strong English skills (oral and written) are mandatory as it will be the main language used throughout the project.

To apply, please attach your CV, a cover letter explaining your research experiences in experimental and numerical approaches and your grades transcript from your M2 and/or engineering degree.

[1] P.-A. Geslin, M. Buchet, T. Wada, and H. Kato. "Phase-field investigation of the coarsening of porous structures by surface diffusion." Physical Review Materials 3, no. 8 (2019): 083401.
[2] M. Mokhtari, T. Wada, C. Le Bourlot, J. Duchet-Rumeau, H. Kato, E. Maire, and N. Mary. "Corrosion resistance of porous ferritic stainless steel produced by liquid metal dealloying of Incoloy 800." Corrosion Science 166 (2020): 108468.
[3] M. Mokhtari, C. Le Bourlot, J. Adrien, A. Bonnin, T. Wada, J. Duchet-Rumeau, H. Kato, and E. Maire "Microstructure characterization by X-ray tomography and EBSD of porous FeCr produced by liquid metal dealloying." Materials Characterization 144 (2018): 166-172.

Work Context

During this PhD under joint supervision (INSA / Tohoku University), the candidate will share his/her time between Lyon and Sendai with long time stays in both places to interact with the researchers involved in the project and conduct experiments in both laboratories.

Constraints and risks

No specific risk

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