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Phd (M/F) : Experimental study of plastic strain localization in polycrystals by electron microscopy-based techniques

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Français - Anglais

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General information

Reference : UPR3346-NADMAA-023
Workplace : FUTUROSCOPE
Date of publication : Friday, June 26, 2020
Scientific Responsible name : Ludovic THILLY
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

The CNRS, at the Pprime laboratory (CNRS, UP, ISAE-ENSMA) in Poitiers-Futuroscope, is recruiting a PhD student as part of the ANR-3DiPolyPlast project.

The PhD topic will focus on objectives 1, 2 and 3 of the 3DiPolyPlast project, via electron microscopy-based experimental techniques. The PhD candidate will work in strong cooperation with two other PhD candidates located at other partners of the 3DiPolyPlast consortium (one at Mines ParisTech/ONERA in Paris and one at ESRF in Grenoble) and working on synchrotron-based characterizations and Discrete Dislocations (DD) simulations.

In details, the PhD candidate will develop and perform different type of studies:
- in situ monotonic testing in the SEM, in combination with (HR-)EBSD on regions of interest composed of ~100 grains. Automated procedures will be developed to acquire the data and extract rotation and strain fields showing the formation of slip bands. This will provide comprehensive evidence of the inelastic deformation mechanisms with very high resolution in a large number of grains while knowing the underlying microstructure entirely,

- from surface EBSD maps or preliminarily collected synchrotron-based 3D X-ray Diffraction Contrast Tomography (DCT) or Topo-Tomography (TT) data, specific grains showing plastic localization will be identified and studied with the highest resolution possible by TEM: for this, the FIB-based lift-out technique will be used to extract the TEM thin foils. The dislocations structures will then characterized by TEM,

- from surface EBSD maps or 3D DCT/TT data, specific aggregates will be identified and extracted by FIB milling. The slice-and-view technique will be combined with EBSD (and possibly HR-EBSD) to reconstruct the 3D volume in terms of grain boundaries arrangements and crystallographic orientations,

This experimental work will provide important complementary inputs to an improved and physically motivated description of crystal plasticity constitutive behaviour for polycrystalline materials.

Work Context

Context: the project 3DiPolyPlast

Understanding the deformation processes leading to the failure of polycrystalline structural materials is one of the key challenges in materials science. Significant progress has been achieved over the past decades, thanks to both cutting-edge experimental characterization techniques and computational methods. Still, the localization of plasticity in slip bands and the propagation of plasticity through a polycrystalline aggregate are not fully understood. The investigation of such phenomena is the goal of the ANR project “3DiPolyPlast” started in 2020, for a period of 54 months.

The key objectives of this project are:
1. Pushing the frontier of experimental characterization of bulk plasticity
2. Determining the contribution of slip band/localization in plastic strain of individual grains
3. Identifying mechanisms governing the propagation of plastic strain in the polycrystal
4. Advancing image-based mesoscale modelling of crystal plasticity.

The PhD student will be based at Institut Pprime, Universtity of Poitiers (pprime.fr).
In addition to the experiments performed at Institut Pprime, the PhD candidate will also participate to synchrotron experiments.

Constraints and risks

Doctoral school registration : SIMME (Sciences et Ingénierie des Matériaux, Mécanique, Énergétique), https://www.u-ldevinci.fr/simme/fr/page-daccueil-ed-simme/

Short duration mobility, within and outside France, is to be scheduled.

Additional Information

The candidate is expected to hold a Master degree in materials science/physics or in mechanics of materials.
He(she) will present excellent communication skills (both writing and oral), including in English. The strong interaction with partners of the project will require a great capacity for team work.

Application: motivation letter, CV, Master degree record, letter(s) of recommendation.


=> Coronavirus information :
the CNRS reserves the right to postpone the recruitment date according to the evolution of the situation in France.

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