Bienvenue sur le site internet du laboratoire LEM3
Actualités au 30/08/2014
Soutenance de thèse de Shiying WANG
* 29 août 2014 à 14h, Room Meißen, Ground floor. At the margin of ICOTOM 17 Conference, organized by Technische Universitaet Dresden, Germany

« Crystallographic characterization of plastic deformation of commercially pure titanium »

Announcement of PhD defense of Ms. Shiying WANG
Abstract
The deformation twinning microstructure and behaviors of commercially pure titanium under different loading modes were investigated by interrupted in-situ SEM/EBSD observation. Based on the crystallographic orientation acquired by EBSD, the plastic energy consumption by twinning was calculated. The selected variant is the one that can maximize the energy consumption to propagate a twin and minimize the energy locally. The activation of twins is always accompanied by accommodative dislocations or twins in their neighborhoods. According to the crystallographic orientation relationship and theoretical calculation, the accommodation deformation mode is verified to be the best one that can accommodate the imposed strain by twinning in its neighboring grain. The activation of low Schmid factor twin and negative Schmid factor twin are evidenced by crystallographic calculation to be the result of local stress concentration. And in this work, a simplified dislocation identification method was proposed based on crystallographic calculation. The present study intends to offer deep insights into the crystallographic features and deformation mechanisms of commercially pure titanium.


Soutenance de thèse de Nan XU
* 29 août 2014 à 16h, Room Meißen, Groundfloor. At the margin of ICOTOM 17 Conference, organized by Technische Universitaet Dresden, Germany

« Study on phase stability, structural and magnetic properties of Ni-Mn-Ga ferromagnetic shape memory alloys by ab initio calculations »

Announcement of PhD defense of Ms. Nan XU
Abstract
Ni-Mn-Ga ferromagnetic shape memory alloys have received great attention due to their giant magnetic shape memory effect and fast dynamic response. A series of first–principles calculations have been performed within the framework of the Density Functional Theory (DFT) using the Vienna Ab initio Simulation Package (VASP). The oscillation of Ni magnetic moment dominates the distribution of the total magnetic moment. The total magnetic moment has been found to increase from austenite to NM martensite through the modulated martensites. Ni-doping relatively stabilizes the NM martensite, whereas proper Mn-doping relatively stabilizes the 7M martensite. Moreover, the perturbation of the magnetic moments by atom substitution is mainly located in the antisite and its close neighbors. It is mainly dominated by their Mn environment (distance and number). The present study is of great significance to improve the functional performances and to design new promising ferromagnetic shape memory alloys.


Proposition de sujet de stage : INSTITUT DE SOUDURE, Yutz
* 25 août 2014

Sujet : Etude de l’applicabilité de l’Emission Acoustique Modale au contrôle et monitoring des structures composites

Stage de 4ème année (BAC + 4)
Début Septembre 2014 à mi janvier 2015
Formulaire d'inscription
Encadrant : S. Yaacoubi
s.yaacoubi@institutdesoudure.com | Tél : +33 (0)3.82.88.79.54
Laboratoire d’accueil : Institut de Soudure Recherche et Enseignement, 4 boulevard Henri Becquerel, F-57970 YUTZ


Soutenance de thèse de Bo YANG
* 1 août 2014 - Room 426, Zhixing building, Northeastern University, Shenyang, China

Soutenance de thèse de Bo YANG

« Fabrication and crystallographic features of epitaxial NiMnGa ferromagnetic shape memory alloy thin films »

Abstract:
In the present work, epitaxial Ni-Mn-Ga thin films were successfully fabricated on MgO substrate by DC magnetron sputtering. The microstructure, phase constituent, crystal structure and crystallographic features of the phases in NiMnGa thin films were investigated by combination of XRD and SEM-EBSD. Based on the local crystallographic orientation acquired by EBSD, the orientation relationships between martensite variants and their interface planes in NiMnGa thin films were fully revealed through crystallographic analyses. According to the crystallographic determined orientation and theoretical calculation, the martensitic transformation sequence is A?7M?NM. The impact of the transformation crystallographic characters together with the specific constrain of the substrate on the microstructure features of the films is fully depicted. The present study intends to offer deep insights into the crystallographic features and martensitic transformation of epitaxial NiMnGa thin films.


Spécialité : Sciences des matériaux
Ecole doctorale : EMMA


Directeur : Claude ESLING (Prof. UL)
Co-encadrants : Liang ZUO (Univ. of Shenyang, Chine), Yudong ZHANG



29
AOUT
Soutenance de thèse
de Shiying WANG
29
AOUT
Soutenance de thèse
de Nan XU
29
AOUT
Séminaire LabEx DAMAS
par Benoît MALARD
11
SEPT
Séminaire
du Professeur N. KHALILI
12-14
SEPT
Les Sciences sur la Place
www.sciencesurlaplace.fr
23
SEPT
Soutenance de thèse
de Jean-Jacques ARNOUX