Seminars


June 19, 2017, 2:00 PM, Amphi 1, ENSAM, Metz Technopole

Seminar from Dr. Rémi DINGREVILLE, researcher at Sandia National Labs (Albuquerque, USA) rdingre@sandia.gov

“The role of grain boundary structure and hydrogen on interfacial fracture toughness”

Abstract:
All grain boundaries are not equal in their predisposition for fracture due to the complex coupling between lattice geometry, interfacial structure, and mechanical properties. The ability to understand these relationships is crucial to engineer materials resilient to grain boundary fracture.
In this presentation, I will present a methodology to isolate the influence of grain boundary structure on the tensile strength and work of separation of grain boundaries using atomistic simulations. Instead of constructing sets of grain boundary models by simply varying the misorientation angle around a fixed misorientation axis, the proposed method creates sets of grain boundary models by means of isocurves associated with important lattice properties. Such properties may include the elastic modulus normal to the grain boundary, the Schmid factor for primary slip, and the propensity for simultaneous slip on multiple slip systems. This approach eliminates the effect of lattice properties from the comparative analysis and thus enables the identification of structure-property relationships for grain boundaries.
As an example, I will illustrate this methodology to study intergranular hydrogen embrittlement. Segregated H emphasizes differences in the selected grain boundary structures.

*Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.​

June 1, 2017, 2:30 PM, Amphi 1, ENSAM, Metz Technopole

Seminar from Prof. Anthony ROLLET, Department of Materials Science and Engineering de la Carnegie Mellon University Pittsburgh (USA)

“Metal Powders, 3D Printing and Synchrotron Measurement”

 

 

 

 

May 9, 2017, 2:00 PM, Room Klepaczko, LEM3 Saulcy, Metz

Seminar from Prof. Terry C. LOWE

“Scientific and Technological Foundations for Pilot Scale Production of Nanostructured Metals

 

Prof. Terry C. Lowe
George S. Ansell Department of Metallurgical and Materials Engineering
Colorado School of Mines
Golden, Colorado 80401 USA

lowe@mines.edu, +1 303 273 3178

 

Abstract – The virtues of creating novel microstructures by Severe Plastic Deformation (SPD) have been explored in virtually every commercial alloy system. However, industrial scale implementations of SPD remain limited. To systematically evolve production of ultrafine grain and nanostructured metals by SPD, a Nanostructured Metals Manufacturing Testbed (NMMT) has been established in Golden, Colorado. Machines for research scale and pilot scale implementation of Equal Channel Angular Pressing-Conform (ECAP-C) technology are operated continuously in the NMMT to systematically evolve the foundational science and manufacturing technologies for SPD. We review highlights of ongoing work for scaling processing of aluminum, copper, magnesium, titanium, and iron-based alloys. Topics important to pilot scale processing include fundamental science to control slip, twinning, and texture evolution, plus industrial issues of tooling tolerance and lifetimes, lubrication schemes, and designing complex thermomechanical processing schemes.

April 4, 2017, 2:30 PM, Room Conseil, IJL, Site Saurupt

Seminar from Matthew KRANE, Invited professor by LabEx DAMAS (WP3)

“Studies of transport phenomena in remelting processing of high temperature alloys”

Matthew John M. Krane
Professor of Materials Engineering
Purdue Center for Metal Casting Research
Purdue University
West Lafayette, Indiana

Remelting processes provide routes to large ingots of specialty metals which have relatively few defects. However, beyond certain limits on ingot size and process speed, several types of defects begin to occur. The heat, mass and momentum transfer and electromagnetics occurring during vacuum arc and electroslag remelting (VAR and ESR) are modeled and sump profiles, macrosegregation patterns, and melt rates are predicted. These results are studied as functions of process parameters and ingot size. During VAR of titanium alloys, DC current levels are sometimes high enough that the sump flow is controlled by Lorentz forces, leading to segregation patterns different from those produced by buoyancy driven flows. The numerical simulations include studies of those two distinct flow regimes in VAR: strong Lorentz driven flow down the center of the sump and weak buoyancy driven flow in the opposite direction. The results demonstrate possible influence of process instabilities on the flow regime and thus macrosegregation. During ESR of nickel-based superalloys, freezing and remelting of a slag skin between the ingot and mold changes the thermal response of the ingot and the electrode melt rate. Preliminary work on uncertainty quantification in this ESR model has been completed and implications for comparison of model results to plant data is discussed.

Biographical Sketch

Dr. Matthew Krane is a Professor of Materials Engineering at Purdue University and a member of the Purdue Center for Metal Casting Research. His research is on design, development, and modeling of materials processes, particularly the solidification processing of metal alloys. Research projects include numerical process modeling of vacuum arc and electroslag remelting and direct chill casting, studying the effects of transport phenomena and thermal strain on the formation and prevention of solidification defects. He has also worked on the through-process modeling of industrial wrought aluminum alloy production, from direct chill casting to various heat treat processes. Other projects examine exergy destruction in pyrometallurgical processing of copper, the investment casting of superalloy parts with thin sections, the microstructural modeling of dendritic growth, homogenization microstructure development, and the prediction of heat transfer in high pressure die casting. Many of these projects include the quantification of uncertainty propagation through the models.

Prof. Krane has been with Purdue Materials since 1996, but his education is three degrees in mechanical engineering (Cornell, BS, ’86; U. Pennsylvania, MS, ’89; Purdue, PhD, ’96), with a concentration in heat transfer and fluid flow.  In addition to consulting with the metals processing industry, his industrial experience includes three years working on thermal issues in design and manufacturing of electronics packaging. Professor Krane’s teaching experience includes heat transfer, fluid mechanics, process design, solidification, materials processing, numerical methods, extractive metallurgy, and ethics in engineering practice.

December 7, 2016, 2:00 PM, Room Klepaczko, LEM3 Saulcy, Metz

Seminar by Ricardo LEBENSOHN, researcher at Los Alamos National Laboratory, Los Alamos, NM, USA, invited by Labex DAMAS

“Multiscale material modelling with polycrystal plasticity at the mesoscale”

Abstract:
Models based on crystal plasticity are increasingly used in engineering applications to obtain microstructure-sensitive mechanical response of polycrystalline materials. Three key elements of these models are a proper consideration of the single crystal plastic deformation mechanisms, a representative description of the microstructure, and an appropriate scheme to connect the microstates with the macro response. The latter can be based on homogenization, which rely on a statistical description of the microstructure, or on full-field solutions, which requires a spatial description of the microstructure. Full-field models are computationally very intensive, preventing their direct interrogation in multiscale calculations. On the other hand, they can be used to generate reference solutions for assessment of approaches based on homogenization or semi-analytical theories. In this talk we will review our recent efforts to develop polycrystal plasticity models and validate them using emerging materials characterization methods, and the different strategies adopted to embed these models in Finite Elements, to solve problems involving complex geometries and boundary conditions with microstructure-sensitive material response.

 

November 23, 2016, 2:00 PM, Room Klepaczko, LEM3 Saulcy, Metz

Two seminars on atomic scale plasticity modelling will be given by invited researchers:

 

1) Dr. Arun Prakash, from Universität Erlangen-Nürnberg (FAU):

“Atomistic simulations of plasticity in small dimensions: Nanocrystals, nanowires and nano foams”

Abstract Prakash

 

2) Dr. Lucile Dezerald, from Institut Jean Lamour, Université de Lorraine, Nancy:

“Ab initio calculations shedding light on atypical plastic behaviors”

Abstract Dezerald

 

October 6, 2016, 2:30 PM, Room Klepaczko, LEM3 Saulcy, Metz

dingreville

Seminar by Rémi DINGREVILLE, invited by Labex DAMAS,

“Mechanics of Finite Cracks: Insights from Two Length Scales”

Abstract

 

September 13, 2016, 3:00 PM, Amphi Eiffel, IJL, Site de Saurupt, Nancy

Seminar by Dr. Mie Ota, invited LabEx DAMAS, September 5 to september 20, 2016

“Fabrication Process of Harmonic Structure Materials with Unique Deformation Behavior”

August 15, 2016, 3:00 PM, Conseil room, IJL, Site de Saurupt, Nancy

Seminar by Colin SCOTT et Irina PUSHKAREVA, CANMETMATERIALS, Hamilton, Canada

“Advanced High Strength Steel Research at CanmetMATERIALS”

Abstract

C.P. Scott, I.Pushkareva, F.Fazeli, B.Shalchi

1 CanmetMATERIALS Advanced Materials Processing, Natural Resources Canada, Hamilton, Ontario L8P 0A5.

The first part of this presentation will be an introduction to the new CanmetMATERIALS research laboratory (CMAT) constructed in Hamilton, Ontario in 2010. CMAT is a part of Natural Resources of Canada (NRCAN) and is the main federal laboratory for structural materials research in the areas of clean energy, pipelines, transport and automotive, nuclear power production and defence. More than 90% of CMAT’s research portfolio is carried out in conjunction with industrial and university partners in Canada and abroad.

In the second part we will present results from several ongoing studies at CanmetMATERIALS on the development of Vanadium microalloying technology for Advanced High Strength Steels (AHSS) applications in automotive body in white, lightweight vehicle armour and air cooled forgings for linepipe fittings. Data obtained on a wide range of steel grades including Dual Phase (DP), microalloyed ferrite, TWinning Induced Plasticity (TWIP) and bainitic X80-X100 grades will be illustrated. Attention will be drawn to several effects we observe which cannot be satisfactorily explained by current theory and require more intensive study – ideas for future lines of research will be discussed.

July 6, 2016, 11:00 AM, room Klepaczko, LEM3, Ile du Saulcy

Seminar by Dr. Marat I. LATYPOV, GeorgiaTech–CNRS UMI 2958, Georgia Tech Lorraine

“Data science approaches to multiscale modeling and quantification of microstructures”

Abstract
Metal forming processes are used as intermediate or final operations to shape metallic materials into products. Shaping the material is accompanied by plastic deformation, which results in significant changes in the microstructure of the material. The microstructure in turn decides the properties of the material and thus the performance of the final product. These interconnections lead to the prime importance of establishing processing–microstructure–property relationships.

In this talk, I will introduce our recent work on two critical ingredients for establishing these relationships: quantification of microstructures and accurate yet computationally efficient models for prediction of strain partitioning and effective properties of heterogeneous materials as well as how these models fit into the broader context of fully-coupled multiscale modeling.

latypov

Biography
Marat Latypov is a postdoctoral researcher in the GT–CNRS joint laboratory at Georgia Tech Lorraine. He received his PhD from Pohang University of Science and Technology (POSTECH, South Korea) in 2014 and Dipl.-Ing. degree from Ufa State Aviation Technical University (USATU, Russia) in 2011. His research interests include materials informatics and data sciences, multiscale modeling, ultrafine-grained materials, and advanced steels.

E-mail: marat.latypov@georgiatech-metz.fr

Websites: mined.gatech.edu, latmarat.net

 

July 7, 2016, 2:00 PM, room Klepaczko, LEM3, Ile du Saulcy

Seminar by Komlan Sénam DJAKA, PhD. LEM3, Team APLI

“FFT methods for solving the elasto-static and the dislocation transport equations in field dislocation mechanics

Abstract

Résumé Séminaire APLI-K-DJAKA

Keywords
Fast Fourier Transforms, heterogeneities, dislocations, transport equation, spectral filters, heterogeneous media, elastic fields.

 

June 8, 2016, 2:00 PM, Conseil room, IJL, Site de Saurupt, Nancy

Seminar by Dr. André PHILLION, Associate Professor, Department of Materials Science and Engineering, McMaster University, Hamilton, Canada

“3D Imaging & Simulations of Fibrous Materials: Applications to paper-based products and proton transport layers within hydrogen fuel cells”

Abstract
X-ray tomographic imaging provides a unique view of the internal structure of materials in 3D. Materials such as paper and proton transport layers (PTLs) are traditionally difficult to characterize because they are very thin and thus sustain only a limited amount of load. In this talk, new image analysis methods to quantify porosity in thin sheet material, and to segmenting paper fibres are presented. Then, the processed datasets are used as the basis for characterizing the strength, permeability, and diffusivity of these complex material systems via image-based simulations.

Biography
Dr. Phillion received his PhD from the Department of Materials Engineering at The University of British Columbia in 2007, where he combined high temperature experimental methods with multi-
scale modelling to investigate solidification processes and casting defects. After completing his PhD, he spent two years (2008-2009) as a Post-doctoral fellow at EPFL, Switzerland in the LSMX Computational Materials, followed by six years (2010-2015) as a faculty member in the School of Engineering at The University of British Columbia’s Okanagan campus. He joined McMaster University in 2016.

June 7, 2016, 2:00 PM, room Klepaczko, LEM3, Ile du Saulcy

Seminar by Professor Anthony ROLLETT, Carnegie Mellon University, USA

“Additively Manufactured Metals”

10

Ross Cunningham, Samikshya Subedi, Sneha Narra, Tugce Ozturk, Harshvardhan Jain, Elizabeth Holm, Brian DeCost, Robert Suter, Jack Beuth, Anthony Rollett

 

Carnegie Mellon University
5000 Forbes Ave., Pittsburgh PA 15213, USA

 

 

 

Abstract:
Additive manufacturing (i.e. 3D printing) is increasingly being implemented for making structural metallic components, yet the nature of microstructural defects and their influence on the mechanical properties are still work in progress. It is important to understand the microstructure and, in particular, porosity in additively manufactured metallic parts as well as the powders used as feedstock in many of the machines. Apart from surface flaws, pores are the primary origin of fatigue failures under cyclic loading. The morphology and location of these pores can help indicate their cause; lack of fusion or keyholing pores with irregular shapes can usually be linked to incorrect processing parameters, while spherical pores suggest trapped gas. Synchrotron-based 3D X-ray microtomography was performed at the APS on additively manufactured samples of Ti-6Al-4V using electron beam powder bed and Al-10Si-1Mg using laser powder bed. The spatial and size distributions of the porosity over a range of processing conditions were determined. Five Ti-6Al-4V samples were fabricated with parameters varied to produce a range of melt pool areas. Imaging samples were sectioned from the bulk and the contour-bulk interface. Similarly, three samples of Al-10Si-1Mg were made with varying process conditions. Marked variations in the type and amount of porosity were observed as a function of the melt pool area.
Beyond measurements of porosity, 3-D printed parts are known to have residual stress as a consequence of the shrinkage that occurs on solidification as well thermal contraction. Thanks to recent advances in high-energy (synchrotron) x-ray methods, a combination of near-field and far-field high-energy diffraction microscopy (HEDM) enables the mapping of both 3-D grain structure and the lattice strains. Preliminary measurement results are presented for printed Ti-6Al-4V. There are many ways in which data analytics could be applied to additive manufacturing. An example is given of the application of machine vision to the classification of different types of metal powders.

Keywords: Additive Manufacturing, 3D Printing, Crystal Plasticity Simulation, High Energy Diffraction Microscopy (HEDM), Computed Tomography (CT), Machine Vision

Acknowledgments: Jon Almer, Edward Cao, Ross Cunningham, Peter Kenesei, David Menasche, Tugce Ozturk, Suraj Rao, Hemant Sha, Samikshya Subedi, Robert Suter, and Xianghui Xiao are thanked for their contributions. NSF, DOE, APS(ANL), the Commonwealth of Pennsylvania, and America Makes supported various aspects of the work.

 

May 13, 2016, 9:00 AM, room 116, IJL, site de Saurupt

Seminar by Professor André PHILLON, Department of Materials Science and Engineering, McMaster University, Hamilton, Canada

“Meso-scale multi-physics modelling of industrial solidification processes”

Abstract:

Meso-scale models based on granular materials are finding use in gaining understanding of defect formation mechanisms during metallic-alloy solidification processes. In this talk, research is presented on the use of meso-scale models for predicting hot tearing/solidification cracking in aluminum alloy casting and welding processes. These models couple solidification modules, mechanical deformation modules, fluid-flow modules, and defect modules in order to first construct the microstructure of the semi-solid, second to simulate deformation and intergranular flow, and finally to comprehensively predict crack formation. Examples will be given for the binary Al-Cu, A356, and AA6061 alloy systems.

Biography:

Dr. Phillion received his PhD from the Department of Materials Engineering at The University of British Columbia in 2007, where he combined high temperature experimental methods with multi-scale modelling to investigate solidification processes and casting defects. After completing his PhD, he spent two years (2008-2009) as a Post-doctoral fellow at EPFL, Switzerland in the LSMX Computational Materials, followed by six years (2010-2015) as a faculty member in the School of Engineering at The University of British Columbia’s Okanagan campus. He joined McMaster University in 2016.

June 6, 2016, 2:00 PM, room Klepaczko, LEM3, Ile du Saulcy

Seminar by Jian WANG (University of Nebraska-Lincoln)

“PURE-SHUFFLE MECHANISMS IN SOLID-SOLID PHASE TRANSFORMATION”

Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526; Los Alamos National Laboratory, Los Alamos, NM 87544 USA

Keywords: Pure-shuffle, Phase transformation, Deformation twin, Atomic scale

Abstract:

Solid-solid phase transformation, such as the transformation between different crystal structures (i.e., face centered cubic vs. body centered cubic, hexagonal close-packed vs. face centered cubic, etc.) and the reorientation of one crystal structure (i.e. twinning), often occurs associated with either temperature change or mechanical loading. Under mechanical loading, the formation of new phase can accommodate plastic deformation which is referred to as phase transformation induced strain or twin induced strain with respect to the transformation type. The created boundaries consequently act as barriers for dislocation motion, in turn, strengthening materials. Using high-resolution transmission electron microscopy (HRTEM) and atomistic simulations (density function theory and molecular dynamics), we explored pure-shuffle transformation mechanisms for nucleation of (i) a face-centered cubic titanium in hexagonal close packed titanium, (ii) zinc-blende InAs in wurtzite InAs nanowires, and (iii) deformation twin {10-12} in hexagonal metals and growth or annealing twins in face-centered cubic metals. The growth of these structures can be accomplished through either shear shuffle or pure shuffle mechanisms, depending on whether marco-scale shear strains will be resulted.

Biography:

Dr. Jian Wang is an Associate Professor at Mechanical and Materials Engineering at University of Nebraska-Lincoln. He received his Ph.D in Mechanical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA, in 2006. After that, He joined Los Alamos National Laboratory and has been working as Technical Staff Member for 9 years. Currently, his research interests are focused on more quantitative exploring the structure-properties relationships of structural and nanostructured materials. He was awarded International Journal of Plasticity Young Research Award, 2015; TMS MPMD Young Leader Professional Development Award, 2013; the LDRD/Early Career Award (2011); and the LANL Distinguished Postdoctoral Performance Award in 2009. He was leading two DoE BES Core programs with focus on (1) Deformation Physics of Ultra-fine Materials and (2) Multiscale Constitute Laws for HCP materials; and two LDRD-ER Award (2013), Los Alamos National Laboratory, USA. He has ~2000 peer-reviewed publications (>4600 citations and H-index = 42, 25 papers selected as 25 Hottest Articles in Materials Science), two book chapters in Dislocations in Solids and 55+ invited/keynote presentations. He is serving as Editorial Boards for several materials journals.

May 2, 2016, 2:00 PM, room Klepaczko, LEM3 Saulcy

Professor Yuri ESTRIN FAA (Fellow of the Australian Academy)
“Using severe plastic deformation to produce fine-grained hybrid materials”

Estrin

 

 

Professor Yuri Estrin FAA (Fellow of the Australian Academy)
Honorary Professorial Fellow
Department of Materials Science & Engineering
Monash University, Australia

 

 

 

 

 

April 12, 2016, 2:00 PM Amphi Eiffel – Nancy sur le site de Saurupt

Stephan MÄNDEL (Leibniz Institute of Surface Modification (IOM) in Leipzig)
“Surface Modification by Energetic Particles – Fundamentals and Applications for Advanced Biomaterials”

The development of ion implantation started around the middle of the last century, leading to its present prevalence in semiconductor processing. Alternative applications for metals or biomaterials have been investigated since the 1960s. In the meantime, process modifications such as plasma immersion ion implantation, broadbeam ion implantation and ion beam assisted thin film deposition lead to a large expansion of the research area.
As bioactivity or biocompatibility is a rather complex phenomena depending on a multitude of factors, bombardment of surfaces with energetic particles appears as a promising method delivering synergistic effects between several, independent phenomena.
Surface sputtering leading to material removal and surface patterning or roughening is combined with athermal phase formation and diffusion processes. Thus, excellent adhesion, corrosion and wear resistance can be achieved within one process while tailoring the surface tribology, cytotoxicity and biocompatibility towards the specific application. Beside examples on fundamental processes, applications of modern biomaterials including titanium alloys, NiTi shape memory alloys, CoCr alloys, and Mg will be presented.

April 11, 2016, 2:00 PM Amphi Eiffel – Nancy sur le site de Saurupt

Darina MANOVA (Leibniz Institute of Surface Modification (IOM) in Leipzig)
“In-situ diagnostics for nitriding of advanced metals (stainless steel, CoCr and NiCr alloys)”

The formation of expanded austenite after nitrogen insertion into austenitic stainless steel, CoCr or Ni base alloys is still not completely understood. Ex situ x-ray diffraction (XRD) investigations, which can be very sophisticated nowadays, lack the exact time evolution while additional annealing processes may occur during cooling phases. However, further information on the samples is necessary to interpret the restricted XRD information, e.g. stress state from sample curvature, nitrogen content and depth distribution from GDOES or SIMS and SEM/TEM for grain size and elemental distribution.
Nevertheless, an integrated picture has emerged concerning the nitriding of (Fe,Co,Ni)Cr alloys: beyond transport through a surface barrier, a transition from supply to diffusion limited nitrogen uptake has been reported. While clear distinction between low nitrogen content (austenite with nitrogen) and high nitrogen content (actual “expanded phase”) is found, the mechanism for the phase transition is still unclear. The decay of the expanded phase leads to nucleation and growth of CrN/Cr2N precipitates and a Cr-depleted phase with consequences for the nitrogen transport during the decay. Stress analysis is further complicated by the observation of peak splitting.

March 9, 2016,  2:00 AM Room Klepaczko – LEM3 – Metz

Two seminars by Prof. Kaveh EDALATI, Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan

14h: A historical review on high-pressure torsion from 1935 to 1988

High-pressure torsion (HPT) is currently on of the most popular severe plastic deformation techniques to create ultrafine-grained materials with novel structural and functional properties. The method is receiving significant attention mainly because of the reports of Prof. Ruslan Z. Valiev and his co-workers in 1988 on the efficiency of the method in creating nanostructured metals. The HPT method was first introduced in 1935 by Prof. Percy W. Bridgman at Harvard University. Bridgman pioneered application of high torsional shearing stress combined with high hydrostatic pressure to many different kinds of metallic materials, minerals, glasses, polymers, lubricants and many other kinds of organic and inorganic compounds. This talk reviews the main findings of Bridgman and his successors (1935-1988) and explains their historical importance in advancement of materials and methods.

14h45 : Significance of severe plastic deformation on hydrogen storage performance

This talk reviews some major findings on the significance of severe plastic deformation on the hydrogen storage properties of metal hydrides, achieved at Kyushu University. The method of high-pressure torsion (HPT) is employed to introduce severe plastic deformation in different kinds of Mg-based and Ti-based hydrogen storage materials. Our main targets are reducing the thermal stability of Mg-based hydrides and easy activation of Ti-based hydrides. Several interesting results are found: increasing the hydrogenation kinetics; easy activation for hydrogen storage; improvement of the air resistance (difficult deactivation); and synthesis new nanostructured materials for hydrogen storage at room temperature. These unique properties are due to the formation of different kinds of lattice defects (dislocations, grain boundaries, stacking faults and fine cracks) and/or formation of new phases.

February 25, 2016,  11:00 AM, Room 116,  IJL, site Saurupt, à Nancy.

Simulations des effets des écoulements sur la croissance cristalline d’un mélange binaire : approche par méthode de Boltzmann sur réseau
By Amina YOUNSI (postdoc research, IJL, dép. SI2M, team Solidification (302))

Résumé
Les modèles à champ de phase sont des outils puissants pour simuler l’évolution d’interface de cristaux, tels que ceux rencontrés dans le procédé de vitrification de déchets radioactifs du CEA. Le but de ce travail est d’étudier les effets hydrodynamiques sur la croissance des cristaux d’un mélange binaire. Une méthode numérique originale, appelée la méthode de Boltzmann sur réseaux (Lattice Boltzmann – LB), est adaptée et étendue pour la résolution et la simulation de modèles de solidification. La méthode LB est une méthode très attractive pour simuler des problèmes hydrodynamiques et nous l’utilisons pour simuler à la fois le problème de changement de phase et la mécanique des fluides. De plus, on établit un nouveau modèle qui tient compte de la variation de densité au cours du changement de phase. Des exemples de simulations relatives à la croissance cristalline et de l’effet d’un écoulement forcé sur cette croissance sont présentés.

Abstract
Phase field models are powerful tools to simulate the interface evolution of crystals, such as those encountered in the vitrification process of radioactive wastes. The purpose of this work is to study the hydrodynamic effects on crystal growth of a binary mixture. An original numerical method, called the Lattice Boltzmann Method (LBM) is adapted and extended for solving and simulating the model of solidification. The LBM is a very attractive method to simulate hydrodynamic problems and we use it for simulating the coupling between the problem of phase change and fluid mechanics. Moreover, we derive a new model to take into account the density change which occurs during the solidification. Examples of simulations relative to various solidification processes including the effect of forced flow will be presented.

January 28, 2016, 3:00 PM in Conseil room (site Saurupt de l’IJL).

Seminar WP3 from Mathieu MCPHIE

Vacuum arc remelting: Behavior of the molten layer

Abstract: The properties of the purified metal product from a VAR furnace depend primarily on the behaviour of the molten material in the crucible. However additional effects could arise from the melting process at the electrode face, which includes the formation and emission of molten metal drops. Preliminary work is performed on the formation of drops from the underside of horizontal surfaces as a model of the VAR furnace. Melting is simulated by considering a one-dimensional surface with a constant in-flow. This is studied for two materials, water and a liquid titanium alloy. It is found that the primary falling drops increase in size with increasing flow rate and that the zero flow rate drop radius is very closely related to the capillary length of the material, being approximately 11-14% larger. The amount of material carried by the primary falling drop as a proportion of the hanging drop just before rupture is found to be very similar in both water and titanium, and may be a universal behaviour. The zero flow rate value of this proportion is approximately 78-80%. Some initial results are shown for 3-dimensional systems.

December 16, 2015, Klepaczko room of LEM3

Seminar from María Teresa PEREZ-PRADO, IMDEA Materials Institute, Madrid, Spain

The controversial microplasticity of polycrystalline magnesium

Abstract

It is well known that plasticity of metallic materials is governed by a competition between the available twinning and slip systems. In magnesium, as well as in other hcp metals, twinning tends to become the dominant deformation mechanism with increasing grain size, with increasing strain rate and with decreasing temperature. The twinning to slip transition is, however, a very controversial topic, and contradictory evidence regarding transition grain sizes, strain rates and temperatures has been reported in the literature.
This talk will focus on recent research which reveals that twinning´s main contender is basal slip and that the transition between both mechanisms is related to the connectivity of grains that are favorably oriented for the latter [1,2]. It will be shown how increasing grain size and strain rate, and decreasing temperature, all contribute to limit the connectivity between grains that are well oriented for basal slip, thus favoring the dominance of twinning. Taking connectivity into consideration allows rationalizing the reported dispersion in transition grain sizes, strain rates and temperatures.

References:
1. C.M. Cepeda-Jiménez, J.M. Molina-Aldareguia, M.T. Pérez-Prado. Acta mater. 88 (2015) 232-244.
2. C.M. Cepeda-Jiménez, J.M. Molina-Aldareguia, M.T. Pérez-Prado. Acta mater. 84 (2015) 443-456.

November 13, 2015, 11:00 AM, Salle du Conseil IJL, site Saurupt, Nancy.

Séminaire organisé par par le LabEx Damas et par l’équipe Solidification de l’IJL

Grain structure, iron precipitation and minority carrier lifetime in multicrystalline silicon
présenté par Mohammed M’Hamdi (Directeur de recherche, SINTEF Materials and Chemistry, Oslo et Professeur adjoint, NTNU, Trondheim, Norvège)

Abstract

Multicrystalline silicon is, together with monocrystalline silicon, the most widely used material in the photovoltaic industry. It contains a high density of extended defects, i.e. grain boundaries and dislocations, and a wide range of impurities, affecting the output solar cell performance. Iron has been identified as one of the most detrimental impurities in multicrystalline silicon, and is found in relatively high concentration in ingots, originating from the crucible, its coating and the silicon feedstock. Iron is present in multicrystalline materials in interstitial state or in the form of metal silicide nano-precipitates, mainly identified as FeSi2. Previous studies have shown that a large majority of iron present in as-grown multicrystalline materials is precipitated. Iron precipitation has a positive impact on the as-grown wafer quality, as the recombination activity of a precipitate per iron atom is generally considered being lower than the recombination activity of an isolated interstitial iron atom. Iron precipitation at extended defects is, however, a strong limitation to the phosphorous gettering efficacy, as only the mobile dissolved iron atoms have the ability to segregate towards the emitter. Due to its relatively high solid diffusivity, iron precipitates mostly at extended defects. Those defects present favorable precipitation sites and act as internal gettering sites during the ingot cooling. Recent improvements in the silicon growth technology have led to the solidification of multicrystalline silicon ingots of higher quality, i.e. with lower densities of dislocation clusters. This newly developed material is commonly referred as high performance multicrystalline silicon (HPMC-Si), and presents a smaller grain size and a higher proportion of random angle grain boundaries compared to conventional multicrystalline silicon. The precipitation behavior of iron is affected by the structure evolution of multicrystalline silicon, and it is of major interest to evaluate and predict the influence of each type of extended defect. This study presents an examination of the spatial occurrence of iron precipitation during the cooling of an HPMC-Si ingot, and aims at investigating using numerical simulation the separate effects of grain-boundaries, sparse intra-granular dislocations, and dislocation clusters and their impact on the minority carrier lifetime.

October 19, in the Klepaczko room of LEM3, from 11H.

The Prof. Ungar is with us for three months since beginning of September, see his presentation on the home page of labex-damas.com.

Microstrain from X-ray and neutron line broadening in terms of dislocation structure related to mechanical properties
by Prof. Tamas UNGAR | Department of Materials Physics, Eötvös University Budapest, Hungary

Abstract:

Diffraction peaks of X-ray or neutron diffraction patterns broaden when the dislocation density exceeds about 5×10^12 m-2, the average grain or subgrain size is smaller than about 1 micron or the average distance of planer defects, twin boundaries or stacking faults, is shorter than about 1 micron. Defect specific hkl dependence enables to separate the different contribution to peak broadening. TOF neutron diffraction patterns were measured in the VULCAN beamline at SNS of Oak Ridge National Laboratory on tensile strained 316 stainless steel specimen. The data were analyzed in terms of the alfa parameter in Taylor’s equation. Dislocation densities were determined in the different texture components of a plastically deformed Zircaloy specimen in the SMARTS neutron diffractometer at the Los Alamos National Laboratory. Slip-modes and slip-systems were determined in individual grains in polycrystalline aggregates of CoTi and CoZr from synchrotron diffraction patterns measured at the APS at Argonne National Laboratory.

 September 28, in the Klepaczko room of LEM3, from 11H.

Seminar by Prof. ZUO Liang

« Microstructural evolutions associated with martensitic and intermartensitic transformations in ferromagnetic Ni-Mn-Ga alloys »

Zongbin Li, Bo Yang, Yudong Zhang, Claude Esling, Xiang Zhao, Liang Zuo

Abstract

September 10, in the Klepaczko room of LEM3, from 11H.

Seminar by Prof. ZHAO Xiang

« Effects of High Magnetic Field on High Purity Fe-C Alloys during Diffusional Phase Transformation »

Abstact

July 2, in the Klepaczko room of LEM3, from 11H.

Seminar by Dr. Nilesh GURAO, Ass. Prof. at IIT Kanpur, India 

« Design and Development of engineering alloys using thermodynamic modelling and texture control: A case study on multi-component multiprinciple MnFeNiCoCu and AA6061 alloy »

Abstract

 June 24, 2015, 14h Saurupt (Amphi Eiffel) – Nancy

Seminar by Edbertho LEAL QUIROS from California State University

« Basic plasma diagnostic and applications using a mirror cusp machine »

 

June 24, 2015, 11h Room Klepaczko – LEM3 – Saulcy, Metz

Seminar by Prof. Adam MORAWIEC, invited Professor by LabEx DAMAS.

« An introduction to analysis of 3D grain boundary data in the space of macroscopic boundary parameters »

Abstract

June 17, 2015, 11h Room Klepaczko – LEM3 – Saulcy

Seminar by Dr. Rémi DINGREVILLE – Sandia National Laboratories, Albuquerque, NM 87185 USA

“From coherent to incoherent mismatched interfaces: a generalized continuum formulation of surface stresses”

Abstract

 

June 16, 2015, 11h Room Klepaczko – LEM3 – Saulcy

Seminar by Prof. Martin CRIMP (Michigan State University), invited professor

“Characterization of grain boundary deformation processes in commercial purity titanium using nanoindentation and crystal plasticity modeling”

Abstract

June 12, 2015, 14h Room Klepaczko – LEM3 – Saulcy

Seminar by  Prof. Antony D. Rollett
« Data mining for correlation research in métallurgie »

The Materials Genome argues for the use of data science to accelerate materials development.  Although there has been much discussion of “big data”, the reality is that materials development will mostly be done with normal, i.e. small data sets.  Nevertheless data science has many tools to offer us that can help us analyze and understand our data sets, especially when the number of parameters is more than, say, three (think of the number of columns in a spreadsheet).  Seeking correlations between variables is a formal way of asking whether, say, yield stress depends on fraction recrystallized.  Finding combinations of variables that can be linked to another variable is another natural analysis, which in traditional metallurgy appears in the form of equations that link, say, martensite start temperature to a combination of composition variables.  Such analyses can be performed with the help of standard, open source statistical analysis tools such as Canonical Correlation Analysis and Principal Component Analysis.  A convenient framework for such analyses is the open source R package.  Students are invited to install R on their laptops and come prepared to step through the examples that will be demonstrated in this seminar.

Link to the package to install: www.r-project.org

The seminar will be available by Internet connection to Adobe-Connect, on simple PC or laptop at the address:
https://connect.unr-unire.fr/r9dt66y1tbl/

Connection will be open from 13H on the 12th June.

 

May 18, 2015, 14h30 Institut Jean Lamour – Parc de Saurupt – Amphi Eiffel

Seminar by Prof. E. SUKEDAI – Okayama University of Science

« A study of nucleation behavior of β-ω phase transformation in β-Ti alloys using electron microscopy »

Abstract

 

February 2, 2015, 14h00 Room Klepaczko – LEM3 – Saulcy

Seminar by Prof. Surya KALIDINDI

« Data Science Approaches for Mining Structure-Property-Processing Linkages from Large Datasets »

GeorgiaTech, Atlanta

The George W. Woodruff School of Mechanical Engineering, USA

Abstract of the talk

January 12, 2015, 14h00 Salle du Conseil – IJL – Saurupt

Seminar by Youssef SOUHAR (Post-Doctoral researcher)

« Numerical modeling of dendritic solidification at a mesoscopic scale »

Collaborators: H. COMBEAU, M. ZALOZNIK, C. BECKERMANN, V.F. DE FELICE, A. VIARDIN

Dendritic (treelike) crystals or grains are the most common growth form in solidification of metal alloys.
Their growth is governed by an intricate interplay between diffusion or convection of heat and chemical species and capillary effects. Furthermore, in castings the growth of den-dritic crystals is influenced by adjacent grains. The grains can “feel” each other due to the over-lap of thermal and solutal fields surrounding each growing grain.

The mesoscopic solidification model – originally proposed by Steinbach, Beckermann and coworkers – overcomes the limitations of phase-field methods: it can be applied at larger scales and can include fluid flow at reasonable computing cost. It consists of the description of a dendritic grain by an envelope that links the active dendrite branches. The grain is modeled as an evolving porous medium and the liquid-solid phase change and convection-diffusion transport are modeled by volume-averaged equations. The velocities of the dendrite tips are determined by the local conditions (temperature, solute concentration) in the proximity of the envelope through an analytical stagnant-film model.

More information…

November 4, 2014, 14h, Room Klepaczko, LEM3, Saulcy

Seminar Team APLI by Stéphane BERBENNI

« A FFT approach for solving elasto-static field dislocation and g-disclination mechanics: applications to twin tips and grain boundaries »

Abstract :
Recently, a small-distortion theory of coupled plasticity and phase transformation accounting for the kinematics and dynamics of generalized defects, i.e., dislocations and generalized (g-) disclinations, has been proposed [1]. In the present contribution, a numerical spectral approach is developed to solve the elasto-static equations of field dislocation and g-disclination mechanics set out in this theory for periodic media. Given the spatial distribution of Nye’s dislocation density and/or g-disclination density tensors in heterogeneous or homogenous linear elastic media, the incompatible and compatible elastic distortions are obtained from the solution of Poisson and Navier-type equations in the Fourier space by using a Fast Fourier Transform method (FFT) based on intrinsic Discrete Fourier Transforms well adapted to the discrete grid. The elastic strain/rotation and Cauchy stress tensors are calculated using the inverse FFT. In order to validate the present spectral approach, comparisons are made with analytical solutions and with Finite Element results for linear isotropic elastic solids. The numerical examples include the stress and elastic rotation fields of single screw and edge dislocations, standard wedge disclinations and associated dipoles, grain boundaries, as well as twin tips seen as g-disclinations. The details on the technique can be found in [2]. 

Références :
[1] Acharya, A., Fressengeas, C., 2012. Int. J. Fract. 174, 8794.
[2] Berbenni, S., Taupin, V., Djaka, K.S., Fressengeas, C., 2014. Int. J. Solids Struct. 51, 4157-4175.

October 29, 2014, 11h, room Klepackzko, LEM3 Saulcy

Prof. Beygelzimer est professeur invité du Labex DAMAS pour une période de deux mois. Il donne un séminaire le 29 novembre, mercredi, à 11H dans le laboratoire LEM3, salle Klepaczko. Son abstract:

A continuum model of plastic deformation of non-compact materials

Prof. Yan Beygelzimer
Donetsk Institute for Physics & Engineering
Ukrainian National Academy of Sciences, Donetsk, Ukraine
yanbeygel@gmail.comhttp://hunch.net/~yan/

The talk presents a model of plastic deformation of non-compact materials. A distinctive feature of the model is that it takes into account the possibility of volume change of materials during deformation under pressure.

A flow function is proposed for porous and powder materials with structurally inhomogeneous structure. Depending on model parameters and the value of porosity, the form of the yield surface corresponding to this loading function can vary from an ellipse (shifted in the negative direction of the hydrostatic stress axis) to a curve similar to an axial cross-section of an egg.

The physical reason for the non-symmetry of the trace with respect to the origin is the partial adaptation to the imposed strain of the structural elements of the material when they are deforming jointly. The constitutive relations based on the proposed loading functions and gradient conditions give a unified framework to study pressure dependent deformation of compact and non-compact  (powder and porous) materials and are able to describe a number of experimentally observed physical effects, the most important are:

  • the emergence, growth, and healing of pores under plastic deformation;
  • the inherent unremovable porosity under full compression of porous and powder materials under constant strain path;
  • the increase of material stability under pressure;
  • the increase in ductility under pressure (in particular, the brittle-ductile transition in hard to deform materials).

October 15, 2014 – 11h – IJL – Nancy – site Saurupt

Andrius Martinavicius

Normandie University, Groupe de Physique des Matériaux, UMR 6634 CNRS, Université de Rouen, INSA Rouen, 76801 Saint Etienne du Rouvray, France
Université de Lorraine, Institut Jean Lamour, UMR 7198 CNRS, Parc de Saurupt CS 14234, F-54042 Nancy, France
viendra nous présenter ces travaux réalisés lors de son post-doc au sein du Labex DAMAS :

Atom probe analysis of nitrided layers in steels: advantages and difficulties

Atom probe tomography (APT) is a technique providing three-dimensional mapping of elements within a small volume of material with a near-atomic resolution [1]. It has shown its potential in studying nitrided steels providing a tomographic view of precipitated nitrides [2],[3]. Despite the remarkable ability to provide three dimensional images of analyzed specimen the quantitative measurement of nitrogen concentration is rather complicated. Since in APT the identification of ions is based on time of flight, ions with the same mass-over-charge ratio will overlap. If the alloy contains some Si, peaks from 28Si++ and 14N+ will overlap in mass spectra preventing correct identification. In addition, part of N potentially evaporates as N2+ and N2++ overlapping with 56Fe++ and N+, respectively. The problem is addressed by nitriding pure Fe with nitrogen enriched to 50% in 15N has been used. It has been possible to establish the relative abundances of different nitrogen molecular species, and quantify the different peak overlaps. Despite the various correction applied to account for these overlaps, the measured nitrogen concentration was still lower than expected. This difference was smaller for lower atom probe analysis temperatures. The possible loss mechanisms will be discussed. The problem of overlap between the peaks of 28Si++ and 14N+ can be party overcome by employment of pure 15N. The advantage of 15N is demonstrated in Fe-Si alloy, where cubic amorphous Si3N4 precipitates form during nitriding.

[1] Kelly TF, Miller MK. Invited review article: Atom probe tomography. Rev Sci Instrum 2007;78(3):031101.

[2] Jessner P, Danoix R, Hannoyer B, Danoix F. Investigations of the nitrided subsurface layers of an Fe-Cr-model alloy. Ultramicroscopy 2009;109(5):530–4.

[3] Jessner P, Gouné M, Danoix R, Hannoyer B, Danoix F. Atom probe tomography evidence of nitrogen excess in the matrix of nitrided Fe-Cr. Phil Mag Lett 2010;90(11):793–800.

September 2, 2014 – Amphi Eiffel – Institut Jean Lamour (Parc de Saurupt), Nancy

Seminar from Prof. Michel RAPPAZ, Ecole Polytechnique Fédérale de Lausanne

« Germination de grains cfc dans les alliages métalliques liquides induite par la formation de structures icosaédrales: une approche thermodynamique »
« Nucleation of fcc grains in liquid metallic alloys induced by the formation of icosahedral clusters: a thermodynamic view »

 August 29, 2014 – Amphi Gallé (site Saurupt)

Benoît Malard du CIRIMAT, fera un séminaire :

Les recherches au CIRIMAT et l’apport des grands instruments à la caractérisation multi-échelle de la transformation martensitique sous contrainte dans un alliage à mémoire de forme CuAlBe.

Mots clés : Recherche Appliquée, Couplage, Diffraction par rayonnement synchrotron et neutronique, In-situ »

 July 21, 2014 – Room Klepaczko, LEM3, Metz

« Nucleation, Propagation and Interactions of Deformation Twins in Hexagonal-close-packed Metals

Dr Jian Wang de Materials Science and Technology Division, Los Alamos National Laboratory (E.U.)

Abstract Deformation twinning is a major mode of plastic deformation in hexagonal-close-packed crystals and exhibits more complex nucleation and propagation mechanisms than those in cubic structure. In this lecture, I highlighted several twinning-associated boundaries that play crucial roles in nucleation, growth, and interactions of deformation twins in hcp metals. According to microscopic characterizations and atomistic simulations, four types of boundaries are reviewed including (1) symmetrical tile grain boundaries (SCTGs) that favor twin nucleation or migrate based on twin dislocations, (2) prismatic-basal boundaries (PBs or BPs) associated with twin nucleation via pure-shuffle mechanism, (3) serrated coherent twin boundaries (SCTBs) associated with migration of twin boundaries via glide and climb of twinning dislocations, and (4) prismatic-prismatic (PPs) and basal-basal (BBs) boundaries associated with co-zone twin-twin interactions. More importantly, these boundaries affect twinning and detwinning processes that may correspond to twinning-induced hardening and seem universal associated with twins in hexagonal-close-packed metals. These findings provide theoretical base for researchers to revisit experimental data, rebuild the frame of twinning mechanisms including nucleation and propagation of twins, and advance the development of materials modeling tools at meso- and macro- scales as well as alloy design.

April 16, 2014 – Room Klepaczko, LEM3, Metz

« Meso-scale understanding of bimetal interface evolution in nanocomposites »

Dr. Irene Beyerlein, éminente chercheur du Laboratoire Los Alamos (E.U.)

Abstract In this talk, I will present recent studies on the synthesis of bimetal nanocomposites that are both ultra-strong and thermally stable. The synthesis routes impose extremely large plastic strains and enable production of this extraordinary nanomaterial in quantities sufficient for structural parts. During processing, the bimetal interface density increases until nanostructuring (< 10 nm) is achieved and remarkably, at the same time, the bimetal interfaces develop an atomically ordered state. To date, our experimental analyses find that these interfaces are stable with respect to straining, high temperature, and light-ion irradiation. Predicting and understanding the evolution of bimetal interface properties during mechanical processing brings new challenges in modeling. By combining atomic- to meso-scale computational modeling we are getting closer to explaining the emergence of such stable interfaces and to ultimately engineering them for target nanomaterial performance.

April 9, 2014 – Room “Conseil”, IJL, Parc de Saurupt, Nancy

« 3D simulation of liquid metal processing using OpenFOAM software. Application to EBM (Electron Beam Melting) process. »

Dr. Alexey MATVEICHEV, Post-doctoral IJL-Labex DAMAS

Abstract Within the framework of Work Package “Process Design” of the Laboratory of Excellence DAMAS, a study has been launched, aiming to perform actual 3D simulations of metallurgical processes involving liquid metal treatment and purification. The open-source platform OpenFOAM was chosen as the supporting software while, among several applications, we have decided to apply our modelling approach to the electron beam melting process.
Electron beam melting (EBM) is a flexible technique for remelting and purification of reactive or refractory metals. At IJL, a laboratory-scale EBM furnace is available, where liquid metal treatment is achieved in a hemispherical water-cooled Cu crucible. A liquid pool is formed inside the button-shaped metal specimen, heated by the electron beam at the free surface. While performing EBM, dissolution kinetics of additional matter introduced in the pool can be studied. Complex pattern of the surface heat source, turbulent flow, and a necessity to know the exact thermohydrodynamic behavior of the pool requires full 3D modeling of the process.
To simulate the process of EB melting, one needs to describe momentum and heat transfer, metal solidification, as well as the development of flow turbulence in the liquid. Surface heat and momentum sources and sinks such as electron beam energy deposition, thermal radiation, heat loss to the cooling circuit, surface tension (i.e. Marangoni flow) must also be addressed in the model. Therefore a new solver dealing with all the above mentioned phenomena was implemented within OpenFOAM platform.
The phase-change model was first validated by comparing computed results with previously known numerical solution of Sn melting in a square cavity. In a second stage, the full EB simulation was compared with experimental data from actual experiments of titanium melting in our electron-beam furnace. The simulations showed good agreement between modeling and experimental data.
Finally the developed model was applied to the dissolution experiments. The influence of the immersion of a refractory sample rod inside the liquid pool was simulated. Results of the simulations showed that the introduction of the cylindrical sample disturbs the flow field inside the bath. The amount of such disturbance depends on the exact location of the dipping.

December 19, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Microstructure, martensitic transformation and magnetocaloric effect in polycrystalline Ni-Mn-Ga alloys »

Dr Zongbin LI

Abstract As a novel type of multi-functional smart materials for potential uses in sensor and actuator devices, Ni-Mn-Ga alloys have attracted considerable attention due to their large output and quick response under magnetic field. These alloys also demonstrate large change in magnetic entropy under the magnetic field at the vicinity of the magneto-structural transformation and thus a giant magnetocaloric effect, which could be potentially exploited for magnetic refrigeration applications. In this work, based on the spatially resolved electron backscatter diffraction (EBSD) technique, the microstructural features of three types of martensite and the martensitic transformation crystallography in polycrystalline Ni-Mn-Ga alloys were studied in detail. Furthermore, possible routes for the texturation of polycrystalline alloys via external field treatment were explored, and the composition dependent magnetocaloric effect of melt-spun ribbons and the property improvement through microstructure control were demonstrated.

December 16, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« The automobile as a catalyst for materials development »

J. David Embury – McMaster University Canada

December 11, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Second-phase-particle Added Grain Refinement of Aluminum Alloys »

Prof. Fuxiao YU – School of Materials and Metallurgy – Northeastern University Shenyang

Abstract Grain refinement of Al alloys by plastic deformation is limited by the high stacking faulty energy associated with aluminum. Severe deformation was proved to be an effective way to refine the microstructure in Al alloys to some extend in recent years. It was found, by the author’s group, that grains in Al alloys of eutectic system with dispersion of second phase particles could be refined into micron even submicron scale simply by conventional deformation techniques such as extrusion and rolling. The resulting microstructure gives rise to superior mechanical properties in terms of strength and ductility. In this presentation, Al-Si alloys and Al-Fe alloys are taken as examples to illustrate the principle of this microstructural refinement. Its potential industrial application which may be utilized to transform the non-deformable cast alloys into wrought alloys will be introduced. Future outlook on the research activities will be discussed on the basis of current findings.

November 25, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

Host: Laszlo Toth

« SOME NEW DEVELOPMENTS IN SEVERE PLASTIC DEFORMATION TECHNIQUES »

Nima PARDIS PhD. Student, Materials Science Engineering, Shiraz University, IranCurrently visiting scholar, Department of Materials Science,Tallinn University of Technology, Estonia

Abstract Considerable attention has been devoted to high pressure torsion (HPT) as well as equal channel angular pressing (ECAP) as the two well-known severe plastic deformation (SPD) techniques for producing ultrafine-grained (UFG) materials. Although these methods are powerful tools for processing UFG materials, other techniques still worth considering as they give the opportunity for investigating different modes of deformation and a better understanding of the deformation behavior of materials at these conditions. In addition, other SPD techniques are sometimes more effective for producing UFG materials in special geometrical shapes which might not be easy to be produced by ECAP or HPT. The same applies to SPD processing of materials with limited workability. This presentation discusses some new developments in severe plastic deformation of materials through simple shear-pure shear modes of deformation as well as presenting an issue on evaluating effective strain at large simple/pure shear deformation condition.

October 7, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Grain subdivision mechanisms in aluminium and magnesium »

Prof. Matthew BARNETT – Deakin University, Australia,Chercheur d’Excellence – Lorraine – DAMAS LEM3

Abstract It is well known that grains subdivide during deformation. In so doing, wrought materials obtain new microstructures and significant changes occur in the stresses required for continued processing. In this talk, two separate grain subdivision mechanisms are discussed. A simple mechanism for continuous dynamic recrystallization in aluminium during hot working is presented and some basic principles of twinning in magnesium are examined. In both cases new crystallites surrounded entirely by high angle boundaries are formed. Finally, the importance of the second mechanism for understanding the strength of magnesium is discussed.

September 24, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Stress states associated with twin nucleation and propagation »

Dr. Carlos N. TOMÉ – Materials Science and Technology DivisionLos Alamos National Laboratory, Los Alamos, NM 87545, USA

Abstract Twinning plays a fundamental role in accommodating plastic deformation and explaining anisotropy and hardening of HCP materials. However, the stresses responsible for twin nucleation and propagation are still not well understood. This presentation is an attempt at discussing some key features and hopefully at throwing some light into the mechanisms responsible for twin activity in Mg and Zr.
Specifically, I will discuss the role played by grain boundaries, stress distributions at GB’s, and neighbor misorientation, upon twin nucleation and twin propagation. These features are implemented in a polycrystal model of nucleation. Local stress calculations in the vicinity of and inside twins are performed. Implications concerning nucleation, twin propagation and detwinning are discussed.

September 20, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Scaling Relationships for Mechanical Behavior in Nanocrystals »

Professor Atul H. CHOKSHI – Department of Materials Engineering, Indian Institute of Science, Bangalore, India

Abstract The grain size is an important length scale of relevance for many aspects of mechanical behavior in polycrystalline materials. While the behavior is very well established for conventional materials with grain size of >1 μm, it is not clear whether such relationships can be extended down to ultrafine nanocrystalline grain sizes. This presentation will critically examine scaling

September 6, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Multiscale modeling of localized deformation in polycrystalline solids »

Seminar Kaan INAL, Associate Professor Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1

Host: Prof. Laszlo S. Toth 

Abstract…

July 9, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Hydrogen Sorption Properties of Ultrafine Mg Based Alloy/ Composite Powders Synthesized by Arc Plasma Method »

Seminar de Jianxin ZOU a,b

a Shanghai Engineering Research Center of Mg Materials and Applications & National Engineering Research Center of Light Alloy Net Forming, Shanghai 200240, P. R. China
b State Key Laboratory of Metal Matrix Composite & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai Jiao Tong University, Shanghai 200240, P.R. China
Abstract…

June 26, 2013 – Room 135, IJL, Parc de Saurupt, Nancy

« From bulk to attograms of matter: applications of Broadband Dielectric Spectroscopy in polymer nanoscience »

Seminar Serghei ANATOLI, CR CNRS au laboratoire IMP (Ingénierie des Matériaux Polymères UMR CNRS 5223 de l’Université Lyon1)

Abstract…

June 24, 2013 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« Polycrystal plasticity simulations using the FFT (Fast Fourier Transfer) technique as an alternative to finite elements ».

Seminar Ricardo LEBENSOHN (Directeur de Recherche à Los Alamos National Laboratory, U.S.A.)

June 20, 2013 – Room 135, Institut Jean Lamour, Parc de Saurupt, Nancy

« From bulk to attograms of matter: applications of Broadband Dielectric Spectroscopy in polymer nanoscience »

Seminar Prof. Abdellah KHARICHA (Université de Loeben (Autriche))

Abstract…

June 12, 2013 – Amphi Gallé IJL – site Saurupt – Nancy

Seminar Ricardo LEBENSOHN (Directeur de Recherche à Los Alamos National Laboratory, U.S.A.)

Seminar LabEx Damas and Equipe Solidification IJL présenté par
Natalia SHEVCHENKO (Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, Dresde, Allemagne)

Abstract…

June 10, 2013 – LEM3 – Room Klepaczko, LEM3 Saulcy, building C, Metz

« The dynamic transformation of deformed austenite at temperatures above the Ae3 »

Seminar Ricardo LEBENSOHN (Directeur de Recherche à Los Alamos National Laboratory, U.S.A.)
Abstract…

June 6, 2013 – LEM3 – Meeting Room 204, LEM3 Saulcy, building B, Metz

« Nanocristalline materials by electrodeposition »

Seminar Prof. Uta KLEMENT (Chalmers University, Gothenburg, Sweden)
Abstract…