Job offers / PhD Positions


PhD Position: Characterization of interface incompatibilities in polycrystals by means of TKD and numerical simulations
* March 3, 2017

« Characterization of interface incompatibilities in polycrystals by means of TKD and numerical simulations »

The project focuses on the role of interfaces (grain boundaries, phase boundaries...) on the mechanical properties of polycrystals. Phenomena like plastic strain localization, which are of great importance because they yield to material fracture, are not yet fully understood and accounted for in numerical simulations. More precisely, the grain-to-grain interactions are not properly introduced in the models.
The behavior of interfaces will be calibrated by means of TKD analysis (Transmission Kikuchi Diffraction) performed on a TiAl model microstructure. Then, numerical simulations will be run and compared to experiments to analyze the impact of interfaces on plastic strain and internal stress field heterogeneity. At first, the aim will be to provide a complete geometrical description of interfaces, namely the crystal disorientation and the interface plane geometry. To this end, the TKD on-axis setup developed at the LEM3 will be extended in view of characterizing the interfaces. This new setup provides orientation maps in a fast manner as well as a spatial resolution the order of the nanometer [1].
Second, the interfaces and their neighborhood will be characterized and modeled, and numerical simulations using finite element approximations will be performed. The model used introduces a particular treatment of interfaces that consists in controlling the evolution of the interface dislocation content during plastic straining [2].
Finally, in order to assess the numerical simulation results by comparison with experimental data, the local elastic strain will have to be estimated from TK D measurements. To this end, a method developed at the LEM3 and based on cross correlation of Kikuchi patterns will be used and improve [3].

1- J.-J. Fundenberger, E. Bouzy, D. Goran, J. Guyon, H. Yuan, A. Morawiec “Orientation mapping by transmission-SEM with an on-axis detector” Ultramicroscopy 161 (2016) 17-22.
2- V. Taupin, J. Chevy, C. Fressengeas “Effects of grain-to grain interactions on shear strain localization” Int. J. Solids Struct. 71, 277-299.
3- B. Beausir, J.-J. Fundenberger, Université de Lorraine - Metz, 2015, ATOM - Analysis Tools for Orientation Maps, http://atom-software.eu/

Requirements: Master in Materials Science. It is a PhD thesis from the Ministry of Education and Research. The score obtained on the theoretical examination of the Master 2 must be greater than 13.5.

Deadline: April 30 2016. Expected start date and duration: from September 2016 for 3 years.

Further information:
E. Bouzy emmanuel.bouzy@univ-lorraine.fr Tel : +33 (0)3 72 74 77 95
V. Taupin vincent.taupin@univ-lorraine.fr Tel : +33 (0)3 72 74 78 43
LEM3 UMR CNRS7239 – Université de Lorraine - Ile du Saulcy – 57012 METZ Cedex 01 – France.

* December 15, 2016

« Analysis of grain interactions from EBSD orientation maps and crystal plasticity modeling »

Contact : Vincent TAUPIN vincent.taupin@univ-lorraine.fr

Master 2 MMSP internship: LEM3 Metz
* October 6, 2016

The Laboratoire d’Étude des Microstructures et de Mécanique des Matériaux, LEM3, was founded in 2011 by merging two CNRS laboratories located in Metz (France). From this fusion has emerged a center for transdisciplinary experimental and theoretical research combining mechanics of solids and metallurgy, materials science, chemistry, and physics, to ensure a better visibility of research in France and an effective knowledge transfer to industrial partners, while maintaining the balance between basic and applied approaches. Through this multidisciplinary nature, the LEM3 collaborates with more than 60 laboratories worldwide.
In several research areas, such as plastic and thermoplastic instabilities, martensitic transformation, microstructure and texture in thermomechanical processing, multi-scale modeling, dynamic behavior of materials, the LEM3 finds itself among the best internationally teams. Its expertise covers a wide range of materials (metals and alloys, smart materials, composites, geo-materials...) and applications (automotive, aerospace, energy, engineering...).
The Transformation, Textures, Topology and Anisotropy of Materials group (3TAM studies microstructures (with their 3D topology) and crystallographic textures (at micro- and macro-scales) of polycrystalline materials, with focus on changes induced by phase transitions during thermal, mechanical and/or physical processing, to better understand how the changes alter macroscopic behavior of materials, especially their anisotropy.

To support our 3TAM team, we are looking for a

Nanoscale study of deformation mechanisms and interface effects in TiAl alloys by nanoindentation and atomic force microscopy

The aim of this work is to contribute to a better understanding of the elementary deformation mechanisms and interface effects involved during a nanoindentation test on TiAl alloys. Subsequent surface deformations will be investigated at the nanometric scale by Atomic Force Microscopy (AFM).

Your tasks

  • You will perform nanoindentation tests.
  • You will perform detailed analyses of deformation microstructures at nanoscale with an Atomic Force Microscope (AFM).
  • Your results will be discussed in the framework of TiAl plasticity.

Your profile

  • You should be a master student in materials science.
  • You should have good knowledge of deformation physics and plasticity of materials.
  • As you will be part of an international team, good communication skills in English and teamwork practices are expected.

We offer
This is a 5 months internship position and can lead to a PhD thesis.

For further information and application please contact:
Dr. Antoine GUITTON (antoine.guitton@univ-lorraine.fr) +33 387 315 387
Prof. Emmanuel BOUZY (emmanuel.bouzy@univ-lorraine.fr) +33 387 315 396