This is a scheme which sponsors selected young materials scientists to lecture throughout Europe as "ambassadors" of the materials science community. Lecturers are selected based on the broad significance of their work and their ability to communicate effectively. Each Lecturer tours several materials science centres in different European countries, with the costs of the lecture tour being carried by FEMS and/or the hosting institution. In addition the lecturers are requested to give a talk at the EUROMAT conference taking place the year after their election. Those interested in hosting a Lecturer can receive further information by contacting the FEMS Secretariat.
The FEMS Lecturers 2014 - 2015
Karlsruhe Institute of Technology, Institute for Applied Materials, Kaiserstrasse 12, Karlsruhe, Germany
Dr. Christian Greiner is awarded the FEMS lectureship 2014 for his pioneering work in the field of contact mechanics and tribology. Analyzing the contact splitting phenomenon in gecko toe pads, he formulated adhesion design maps and developed bio-inspired fibrillar adhesives. He now works on the role of structural changes for nanoscale friction, and on water condensation in frictional contacts
Materials Tribology: An emerging field in materials science
The science of interacting surfaces in relative motion (tribology) is of key importance in all systems containing moving parts. Friction, wear and the associated energy dissipation are major challenges from nanoelectromechanical systems, over hip prosthesis to offshore wind turbines and the deployment of satellites. In recent years, it has become evident that the tribological properties of a material, like friction coefficient and wear rate, strongly depend on the evolution of a nanocrystalline surface layer during the very beginning of a tribological system’s lifetime. The materials science-based mechanistic understanding of this microstructure evolution under tribological loading is still poor. Consequently, this is the research topic that my group is concentrated on. In my contribution, I will focus on a reciprocating motion and on model materials like oxygen-free high-purity copper in contact with a sapphire ball. One of the parameters we systematically varied was the sliding distance. I will present how an annealed microstructure is transformed into the above-mentioned nanocrystalline surface layer with increasing sliding distance. We follow this evolution with scanning electron and focused ion beam microscopy, accompanied by transmission electron microscopy and (3D)EBSD. One of the goals of this study is the formulation of a model description of the microstructural changes based on energetic and mechanistic considerations in order to understand these changes and their influence on tribological properties. This might allow for materials with tailored ultrafine microstructures, combining low friction forces and very small wear rates.
Centre des Matériaux, Mines ParisTech, CNRS UMR 7633,Evry France
Henry Proudhon’s research addresses extremely challenging problems in materials science, such as short cracks propagation (fatigue), plasticity in polycrystalline materials and solid damage at contacts (fretting).
His original approach associates computer modelling in mechanics (multiscale mechanical behaviour…) and physics (coherent diffraction…) with experimental developments, e.g. in ESRF, and brings direct insight from the material microstructure to the mechanical properties.
Deformation and cracking of structural materials: from synchrotron X-rays investigations to computational mechanics
The drive for innovation pushes forward better performances of structural materials subjected to severe service loads (eg. superalloys in turbine blades, steel rail/wheel contact, fatigue of aerospace Al alloys...). More than ever, understanding the deep nature of plastic deformation and fatigue fracture of such materials appears as extremely important.
Third generation synchrotrons (and free electron lasers in the future) are developing through Europe to help scientists to investigate material problems, allowing unprecedented in situ experiments. Damage can be seen non destructively in three dimensions with a submicronic spatial resolution, stress probed by diffraction while the microstructure of the material can now also be fully determined.
In the mean time, plasticity and fatigue fracture remain passionate topics to study and model, with much to discover. Conducting key experiments to serve as input to computational mechanics calculation (for instance by finite elements using crystal plasticity) is a promising way forward. Calculating real microstructures and real crack geometries from tomographic images lead to very large scale calculations only possible with the advent of parallel and grid computing.
Several studies adopting this philosophy will be presented including fatigue cracking of a titanium alloy which led to a new model for crack propagation in crystalline materials. An outlook about recent progress in the nanoscale where the challenges are numerous (European network GDRi Mecano), will be presented.
TMS – FEMS Young Leader International Scholar Program
The Minerals, Metals & Materials Society (TMS)and the Federation of European Materials Societies (FEMS) established a joint Young Leader International Scholar Program to promote young member activities and strengthen the collaborations between these international societies. Each society will identify representatives who will present a lecture at a central event of the correspondent society and will tighten the links between USA and European in the area of materials science and engineering.
TMS - FEMS Scholar 2015
Kyle S. Brinkman
Associate Professor Materials Science and Engineering, Clemson University
Kyle Brinkman is an Associate Professor in the Department of Materials Science and Engineering at Clemson University in Clemson, South Carolina. He received his Ph.D. in Materials Science and Engineering from the Swiss Federal Institute of Lausanne (EPFL), obtained an M.S. in Materials Science and Engineering and a B.S. degree in Chemical Engineering from Clemson University. He recently joined Clemson in 2014 from the DOE’s Savannah River National Laboratory (SRNL) where he was a Principal Engineer in the Science and Technology Directorate and Program Manager for Energy Efficiency and Renewable Energy Technologies. Prior to working at SRNL, Kyle was a fellow of the Japanese Society for the Promotion of Science working in a Japanese “National Laboratory” the National Advanced Institute of Science and Technology (AIST) in Tsukuba, Japan. His research is focused on electronic ceramics for gas separation and processing in commercial and nuclear domains, structure/property relations in solid oxide fuel cell systems, and radiation tolerant crystalline ceramics for applications in nuclear energy.
The FEMS Lecturers 2012 - 2013
The Supramolecular Nano-Materials and Interfaces Laboratory –SuNMIL, Ecole Polytechnique Fédérale de Lausanne – EPFL, Lausanne
After receiving a Bachelors and Masters degrees in Physics from the University of Lausanne (CH) – both with honours, Kislon Voïtchovsky obtained in 2007 a DPhil in Biophysics from the University of Oxford (UK) with a thesis on the characterization of biomembranes by using AFM. Part of his thesis was done in collaboration with NTT basic research laboratory, Atsugi, and with the research group of Prof. Ando at Kanazawa University, both in Japan. He was granted the Arthur Cooke Prize of the University of Oxford Physics Department for his work. Dr. Voïtchovsky was 2008 –2010 as SNSF Post-doctoral Research Fellow at the MIT Massachusetts Institute of Technology (USA) where he worked on an experimental approach based on AFM to image and quantifysolid-liquid interfaces with sub-nanometerresolution. He received 2009 the Nature Materials Award and 2011 the Ambizione Career Award of the Swiss National Science Foundation.
His research focused initially on the biomechanics and structure-function relationship of membrane protein studied with scanning probe microscopy. Given the importance of ionic effects on local hydration effects (interfacial effects with the surrounding liquid) he developed a strong interest in solid-liquid interfaces at the molecular level – he was awarded this FEMS prize with a lecture in this area.
Measuring wetting at the nanoscale
Solid-liquid interfaces (SLIs) occupy a central role in many phenomena ranging from surface electrochemistry to heterogeneous catalysis, heat transfer, proteins folding and function, ionic effects and molecular self-assembly. All these processes crucially depend on the particular structural arrangement of the liquid molecules close to the solid. This so-called interfacial liquid tends to be more ordered and dense than bulk liquid due to its interaction with the solid’s surface. At the macroscopic level, these interactions are usually characterized by the work of adhesionWSL, effectively the work necessary to separate the solid from the liquid. The wetting of the solid by the liquid is quantified by WSL, with high values indicating good wetting.
Experimentally, SLIs are typically investigated through diffraction techniques and WSL quantified with contact angle measurements. These techniques generally require averaging over large areas, hence rendering measurements particularly challenging for irregular SLIs, for example if the solid exhibits nanoscale domains with different affinities for the surrounding liquid.
These difficulties can be overcome using an approach based on amplitude-modulation atomic force microscopy (AM-AFM). When operated in a particular regime, AM-AFM can be used to gain semi-quantitative information about the local WSL with sub-nanometer resolution. The approach effectively provides simultaneous maps of the interface topography and of the local wetting properties, often with atomic- or molecular-level resolution of the solid. The method has been successfully applied to study interfaces formed by liquids with minerals, biological membranes as well as synthetic nanostructures. The results show that molecular-level structural effects within the SLI can lead to unexpected macroscopic changes in the interface properties. This is the case for nano-patterned surfaces where nanoscale domains exhibiting dissimilar affinities for the liquid can to tune the surface wetting properties solely through the particular spatial organization of the different domains.
Nanochemistry Laboratory, CNR-Institute for Organic Synthesis and Photoreactivity – ISOF, Bologna, Italy
Vincenzo Palermo received a Masters degree with honours in Industrial Chemistry in 1995 at the University of Bologna (IT). After working as a guest scientist at the University of Utrecht (NL), at Steacie Institute of the National Research Council (CND) and the research division of Procter & Gamble in Rome (IT) he obtained 2003 his Ph.D. in physical chemistry at the University of Bologna (IT) in a joint project with the CNR Istituto dei Composti del Carbonio ICOCEA also in Bologna. Vincenzo Palermo won two graduate student awards at the E-MRS Conference 2003 and at the European Conference on Molecular Electronics 2005; he received in 2006 the Young Scientist Award in materials science of the Italian Society for Microscopical Sciences (S.I.S.M.).
The initial area of interest of Dr. Palermo was on the atomic-scale characterization of surfaces for microelectronic applications; his current work covers the production and nanoscale characterization of new materials for optoelectronics, photovoltaic applications and organic semiconductors as well as the fabrication of new materials by self-assembly and supramolecular chemistry of nanosized building blocks. He received this FEMS award with a lecture about the supramolecular functionalization of graphene.
Not a molecule, not a polymer, not a substrate... the many faces of graphene as chemical platform
What is, exactly, graphene?
While we often describe graphene with many superlative adjectives, it is difficult to force this (superlative) material within a single chemical class.
The typical size of Graphene is atomistic in one dimension of space, and mesoscopic in the other two. This provides graphene with several, somehow contrasting properties.
Graphene can be can be patterned, etched and coated as a substrate. Though, it can also be processed in solution and chemically functionalized, as a molecule. It could be considered a polymer, obtained by bottom-up assembly of carbon atoms, but it can be obtained from top-down exfoliation of graphite (a mineral) as well. It is not a nano-object, as fullerenes or nanotubes, because it does not have a well-defined shape; conversely, it is a large, highly anisotropic, very flexible object, which can have different shapes and be folded, rolled or bent to high extents.
In this presentation, we will discuss the state of the art and possible applications of graphene in its broader sense with a particular focus on how its “chemical” properties, rather than its well-known electrical ones, can be exploited to develop original science, innovative materials and new technological applications.
TMS - FEMS Scholar 2013
Amy J. Clarke
Materials Science and Technology – Metallurgy Group, Los Alamos National Laboratory, New Mexico, USA
Amy Clarke received her Bachelor of Science degree in Metallurgical and Materials Engineering from Michigan Technological University (MTU) in Houghton (MI, USA) and her Master of Science degree in Metallurgical and Materials Engineering from the Colorado School of Mines (CSM) in Golden (CO, USA). She was a visiting researcher in 2004 at the Laboratory for Iron and Steelmaking with Professor De Cooman at Ghent University (BE) and in 2005 with Professor Rizzo at the Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio) in Brazil. She received her Ph.D. in Metallurgical and Materials Engineering from the Advanced Steel Processing and Products Research Center (ASPPRC) at the Colorado School of Mines (CSM) in Golden (CO, USA) in 2006 for her dissertation entitled “Carbon Partitioning into Austenite from Martensite in a Silicon-Containing High Strength Sheet Steel”. Dr. Clarke has been granted several honors and awards, including: the Willy Korf Award for Young Excellence (2007) for her Ph.D. research, a TMS Young Leader Professional Development Award (2008), a TMS/Japan Institute of Metals Young Leader International Scholar (2010) award, and a United States Department of Energy Office of Science Early Career Research Program Award and a Presidential Early Career Award for Scientists and Engineers (PECASE) in 2012. Dr. Clarke was a G.T. Seaborg Institute Postdoctoral Fellow (2006-2008) and a Postdoctoral Research Associate (2009-2010) with the Metallurgy Group of Los Alamos National Laboratory (LANL) in Los Alamos (New Mexico, USA) and a Senior Development/Research Engineer (2008-2009) in Advanced Materials Technology at Caterpillar Inc. in Mossville (IL, USA). Since 2010, Dr. Clarke has been a Research and Development Scientist in the Metallurgy Group at LANL.
The research experience of Dr. Clarke includes in-situ analyses of materials using x-rays, neutrons, and protons at National User Facilities; the study of liquid-solid and solid-state phase transformations; the evolution of microstructure and properties associated with processing variations; and microstructure characterization of uranium, steel, and aluminum alloys.
Direct Interrogation of Metallic Alloys during Melting and Solidification
A solidification microstructure is the product of the processing path used to create it. Understanding this linkage is vital for structural materials because the solidification microstructure profoundly affects properties and performance. Destructive, post-mortem microstructure analysis can provide insight into what occurred at elevated temperatures, but in-situ observations during processing provide direct evidence as to how the microstructure evolves. Transparent organic analogs have been used to simulate solidification in metallic alloys in order to test aspects of solidification theory, but in-situ characterization techniques now afford direct interrogation of metallic alloys during synthesis and processing. In this work, synchrotron x-ray radiography/tomography and proton microscopy (first experiments) were used to directly interrogate small and large volumes, respectively, of metallic alloys during melting and solidification. These capabilities will permit the advancement of solidification theory, the development of predictive solidification and microstructure evolution models, and in-process adjustments through feedback systems to dynamically control microstructure evolution.
The FEMS Lecturers 2010 - 2011
Dr Joanna Michalska
Univ. of Technology Katowice, Poland, Joan...@polsl.pl
Corrosion of superalloys, steels, titanium and magnesium alloys
Joanna Michalska is a native of Poland. She was awarded an MSc degree in chemistry in 2002 and a PhD in materials engineering in 2007 at the Department of Materials Science at the Silesian University of Technology, Poland.
Her research area concerns mainly electrochemical corrosion aspects in degradation and corrosion studies of engineering materials. She has also actively taken part in other scientific projects related to materials for aerospace applications, biomaterials and hydrogen damage phenomena. Joanna is experienced in many materials characterization techniques (corrosion testing, scanning electron microscopy, light microscopy with special techniques of observation, quantitative description of microstructure, electrolytic and potentiostatic etching).
She has authored more than 40 scientific papers in international journals and conferences and some of them were honored and rewarded. As adjunct lecturer she is also recognized for being an excellent tutor for the University’s students. In 2007 Joanna received the Buehler Best Paper Award for her publication in Materials Characterization (2006, vol. 56, p. 355-62) granted by the International Metallographic Society and Materials Characterization Journal. She was recipient in 2010 of the FEMS Young Lecturer Award (Federation of European Materials Societies). Her FEMS lecture is entitled “Microbial Aspects in Corrosion Studies”.
Dr Xavier Sauvage
Université de Rouen, France, xavi...@univ-rouen.fr
Atom probe tomography for understanding deformation induced atomic transport, interdiffusion and phase transformations
Xavier Sauvage graduated in mechanical engineering from the Ecole Normale Supérieure de Cachan (1996). After receiving a master degree in physics of materials (University of Rouen, 1997) he was awarded a PhD from the same University in 2001 on the “Atomic scale investigation of phase transformations in nanoscaled composites processed by severe plastic deformation”. He then spent a year in the Max Planck Institut in Stuttgart as a post-doc fellow. During this time, he was involved in the HRTEM investigation of order fluctuations in Cu3Au close to the critical temperature. At the end of 2002 he joined the CNRS (France) as research scientist to lead research on nanostructured materials and severe plastic deformation at the University of Rouen. Using Atom Probe Tomography in combination with transmission electron microscopy, he investigates deformation induced atomic transport, interdiffusion and phase transformations especially in bulk nanostructured materials processed by severe plastic deformation. He is co-author of more than 40 papers, has been an invited speaker in 10 international conferences and was recipient in 2009 of the “Jean Rist Medal” award (attributed by SF2M, Société Française Métallurgie et de Matériaux) and in 2010 of the FEMS Young Lecturer Award (Federation of European Materials Societies).His FEMS lecture is entitled "Mg segregations along grain boundaries in an aluminium alloy processed by SPD".
The FEMS Lecturers 2009
Dept. of Materials Science and Engineering, Royal Institute of Technology, Stockholm, Sweden
Born in 1974 in Moscow (Russia), in 1996 she graduated with honors from Moscow Institute of Physics and Technology. She completed her PhD in 2000 in the field of “Colossal Magnetoresistance materials”. In 1998 her research work was selected as “Best research in the Low Temperature Physics” by the Russian Academy of Sciences and in 2001 she received a “Best young scientists of Russia” award. After finishing her PhD she joined Royal Institute of Technology (Sweden) as a postdoc and in 2004 has received a “Senior researcher” Assoc. Prof. equivalent position from the Swedish Research Council. In 2005 she was selected as a “Future Research Leader” by the Swedish Foundation for Strategic Research. She is now leading the “Engineering Materials Physics” group at the Department of Materials Science and Engineering of the Royal Institute of Technology. The group is mainly involved in design of new functional materials for magnetoelectronic and spintronics applications, nano-to-micro scale patterning and component design.
InkJet technology for flexible patterning of functional materials
With the development of nanoscience and methods of design and fabrication of nanomaterials the availability of inexpensive easy to use tools capable of large area patterning of nanoscale materials and structures is becoming increasingly important. InkJet technology has been developing rapidly over the last decade for high-resolution photo printing and has now expanded into patterning of functional materials. Piezoelectrically driven InkJets operate at room temperature in ambient conditions and thus are compatible with a wide variety of materials from ceramic and magnetic nanoparticles to carbon nanotubes and proteins. A variety of substrates from paper to glass and plastics can be used. Some of our recent developments are related to direct patterning of oxides (e.g. ZnO, MgO) for optics and magneto-optic components. One of the targeted applications is UV sensing.
Department of Mechanics, Politecnico di Milano, Italy
Prof. Eng. Carlo Mapelli was born at Inzago (MI) on 23-10-1973 and graduated in Materials Engineering at Politecnico di Milano in October 1998. In January 1999 he passed the qualification for the admission to the PhD in Metallurgical Engineering at Politecnico di Torino. In March 2001 he became a Researcher in the scientific area designated ING IND/21 in the Section of Materials of the Department of Mechanics at Politecnico di Milano. In 2002 he was awarded the Daccò Prize of the Italian Association of Metallurgy (AIM) for his researches aimed at the understanding of the microsegregative phenomena in free-cutting steels. In January 2003 he obtained his PhD in Metallurgical Engineering at Politecnico di Torino for researches concerning the problems connected to the plastic deformation of metals. In March 2005 he became Associate Professor in the Dipartimento di Meccanica - Politecnico di Milano where he presents the courses: Steelmaking, Metallurgical technologies, Plastic deformation of metals, and Metallurgy.
His scientific activity has focused on the following subjects:
- thermodynamic and kinetics of the steelmaking processes
- solidification of metallic materials
- study of the thermodynamic cycles of metallic materials and their working technologies
- features of archeometallurgical products
- failure analysis.
New opportunities for improving the formability of duplex stainless steels through specifically designed thermo-mechanical processes
A weakness of duplex stainless steels is their poor formability, which is due to a strong tendency towards thinning. Specifically designed laboratory rolling trials have been undertaken at different temperatures on 2205 duplex steel grades subjected to different reduction ratios and possible solution quenching. The rolling operations have been performed in symmetric and asymmetric conditions in order to impose different straining on the bulk regions of the laminated sheets. The mechanical properties, the micro-structural features and the texture characteristics have been defined for each condition and discussed on the basis of the results of finite element simulations performed using a Navier-Stokes approach. Such an approach allows clarification of the stress and strain field induced in the rolled product. Promising results for the design of steel microstructures for future industrial applications have been obtained and will provide improved control of the mechanical properties of duplex stainless steels.
Other Recent Lecturers
- Dr Christine Blanc, ENSIACET, Toulouse, France (chri...@ensuacet.fr)
Modelling the corrosion behaviour of copper-rich aluminium alloys: galvanic coupling between different aluminium-copper model alloys
- Dr Søren Fæster Nielsen, Risø National Laboratory, Denmark (soer...@risoe.dk)
Tomography and Diffraction
- Dr Paul Michael Weaver, University of Bristol, UK (firstname.lastname@example.org)
Hierarchical Materials and Structures
- Dr Paul A. Midgley, University of Cambridge, UK (email@example.com)
3D TEM: a new Perspective for Materials Microscopy
- Dr Benoit Devincre, Laboratoire d’Etude des Microstructures, CNRS-ONERA, Chatillon Cedex, France (firstname.lastname@example.org)
From Dislocation to Strain Hardening: can Discrete Dislocation Dynamics simulations make it
- Dr Aránzazu del Campo, Max-Planck-Institut für Metallforschung, Stuttgart, Germany
Tailored surfaces with tunable adhesion
ENSIACET ( School of Chemical Sciences and Engineering), Toulouse, France (Chri...@ensiacet.fr)
Christine Blanc was born in 1971 in France. She studied Chemistry and Science of Materials at the School of Chemistry in Toulouse (graduated in 1994). She did her thesis work on the susceptibility to pitting corrosion of different aluminium alloys and received her PhD in 1997. She is now an Assistant Professor at the ENSIACET ( School of Chemical Sciences and Engineering) in Toulouse. She gives lectures on Material Sciences and she is the head of a teaching section for third year students "Durability of Materials and Structures". Her research focuses on the corrosion processes affecting the materials and she is also interested in the protection against corrosion. She was awarded the 2001 H.J. Engell Prize from The International Society of Electrochemistry (ISE) and the 2005 Jean Rist medal from the French Society of Metallurgy and Materials (SF2M).
Modelling the corrosion behaviour of copper-rich aluminium alloys: galvanic coupling between different aluminium-copper model alloys
In commercial aluminium-copper alloys, the presence of various alloying elements induces the formation of different metallurgical phases: among these phases, coarse copper-rich intermetallic phases are known to be initiation sites for corrosion in various corrosive media. The reactivity of copper-rich phases and the galvanic coupling between these phases and the adjacent matrix has often been studied in the litterature but further results are still necessary to better understand these phenomena. Here, aluminium-copper alloys were synthesized to model the matrix and the copper-rich intermetallics; this talk is devoted to analysis of the galvanic coupling between these model alloys.
In a first step, Al-Cu alloys, containing 0 to 100 at.% Cu, were deposited onto aluminium substrates using an Atom Tech Ltd magnetron sputtering. Galvanic coupling tests consisted of recording the variation of galvanic current with time resulting from coupling of two Al-Cu alloys in 0.1M Na 2SO 4 solution. Galvanic coupling between a and q phase-containing model alloys has revealed that the anodic a phase did not suffer corrosion and remained in the passive state. Conversely, sulphate ions induced pitting of the cathodic q phase. Further, the higher the copper content of a phase, the greater its susceptibility to pitting.
In a second step, local electrochemical impedance spectroscopy (LEIS) was used to characterize the corrosion behaviour of three systems: pure aluminium, Al-20at%Cu and Al-40at%Cu model alloys. Model couples were also synthesized with a first layer of pure aluminium partially covered by a second layer of binary Al-Cu alloy to simulate the couple matrix/intermetallic particles. For the model couple, LEIS allowed the electrochemical behaviour of each material constitutive of the couple to be individually followed. Further SEM observations and SIMS analysis showed the dissolution of copper from Al-Cu model alloys simulating intermetallic particles and a deposition of this element on pure aluminium, simulating the matrix in agreement with observations carried out on commercial Al-Cu alloys. Comparison of the results obtained on individual model alloys and on model couples allowed the coupling effect to be studied.
Risø National Laboratory, Denmark (soer...@risoe.dk)
Dr. Søren Fæster Nielsen is a scientist with the Materials Research Department at Risø National Laboratory, Denmark, and was nominated as the FEMS Lecturer for 2005 by the Danish Metallurgical Society (DMS). He studied physics at the H.C. Ørsted Laboratory at Copenhagen University receiving his Ph.D. in 2000 for synchrotron X-ray radiation studies of deformation in metals. As a post-doctoral researcher he participated in developing the three dimensional X-ray diffraction microscope placed at the material science beamline at ESRF in France. He currently holds a Research Fellowship for two years funded by the Danish Technical Research Council. He has published 30 articles in international journals and conferences. His prize consists of a bursary of up to €1500 to cover the costs of presenting his lecture in three different countries and €1500 in cash on completing the series. His first presentation took place on Wednesday 7th September during EUROMAT 2005 in Prague, Czech Republic, where the award had been presented to him during the Opening Ceremony.
Tomography and Diffraction
This lecture explains how 3D strain distributions in composite material can be studied by applying synchrotron X-ray tomography on samples with embedded marker particles.
Paul Weaver is Senior Lecturer in Aerospace Structures, and an EPSRC Advanced Research Fellow. He studied Materials Engineering at Newcastle University, UK where he obtained a First class degree for which the Institute of Materials awarded him its Royal Charter Prize. He worked on 3-D composites for his PhD before undertaking a postdoctoral role under Prof. MF Ashby at Cambridge University. Here, he studied the interactions between materials properties and section shape on structural performance. For the last 5 years he has had a lecturing post at the Aerospace Department of Bristol University, UK. He has close working relationships with Agusta-Westland Helicopters , Airbus UK and NEG-Nicon, with whom contracts approaching 1 million Euros have been secured. His interests remain in the area of exploiting structural efficiency for design purposes through materials tailoring. As such he is developing new predictive techniques for buckling of anisotropic plates and shells. This work has caught the interest of NASA Langley where Weaver has spent the last 3 summers consulting on structural design issues making use of the inherent anisotropic properties of composite materials. He has published in excess of 50 scientific papers in international journals and conferences.
Hierarchical Materials and Structures
The seminar discusses two key aspects of the interrelationship between material and geometric properties on structural performance. The first part concerns the boundaries between structured materials and efficient structures. In particular, at what length scale is it more appropriate to think of the material as a structure. The second half of the talk introduces concepts for innovative structural response using elastically - tailored orthotropic and anisotropic materials. Applications include manufacture of complex shapes to morphing structures.
A When is a material a structure and vice-versa?
It is well-known that adding porosity to a material increases its structural efficiency. This is done by making the material cellular in structure - (honeycomb in 2- and foam in 3- dimensions). Depending on the length scale the result is either thought of as a material, such as polymeric foams or just an efficient structure (space frame structures such as the Eiffel Tower). When the length scale is small the efficiency gain is best described in terms of Ashby's shape factor. However, at large length scales the description is less clear. Issues regarding the development of a general taxonomy that is independent of length scale will be discussed.
B Structural Utopia or something for nothing!
Materials stretch if you pull them or indeed develop curvature when subject to bending. Isotropic materials do this and little else. However, anisotropic materials can do much more! Essentially, it is possible to develop a material with up to 21 independent elastic constants meaning that such a material may bend, twist and shear as well as stretch, when pulled. Polymeric laminated composite materials give scope for tailoring the specific response of a material by changing the fibre orientation of a ply, layer-by layer through its thickness. In this sense, high-performance polymeric composites may be thought of as structured materials or indeed hierarchical materials. Convention dictates that much of the anisotropic response is designed out of the composite. However, this talk takes the perspective that such response may actually be desirable. Examples are drawn from the aerospace and natural worlds to demonstrate many unique positive advantages of anisotropic composites.
Dr Paul Midgley is a University Senior Lecturer and Director of the Electron Microscopy Facility at the Department of Materials Science and Metallurgy. He studied Physics at the H.H. Wills Physics Laboratory at the University of Bristol, receiving his PhD in 1991 for electron microscopy studies of high Tc superconductors. He then held two Research Fellowships, the first funded by The Royal Commission for The Exhibition of 1851, the second by The Royal Society. He moved to Cambridge in 1997. He has studied a wide variety of materials by electron microscopy and developed a number of novel electron microscopy techniques. He and his research group have developed new analytical techniques using EFTEM, STEM and electron holography and applied these to materials systems at the nanometer level. Recently, he has worked on the development of electron tomography using a new STEM-based approach that has wide applicability in materials science. He has written over 100 articles and is invited regularly to speak at conferences around the world.
3D TEM: a new Perspective for Materials Microscopy
The push for nanotechnology and the increasing use of nanoscale materials brings with it the need for high spatial resolution imaging and analysis. The transmission electron microscope (TEM) is a remarkably powerful and versatile instrument and in many ways ideal for such characterisation. Conventional use of a TEM is to section the object of interest and examine 2D slices assuming either uniformity in the 3rd dimension or speculating on the 3D structure from the projection. However, as the lateral dimensions of a feature approach that of its depth, as is happening in modern semiconductor fabrication, the electron microscopist will be required to examine truly 3-dimensional objects and a single projection will not be adequate for a complete description. Stereo microscopy offers some insight into the 3D nature of an object but for true quantitative 3D analysis, one has to turn to tomography as a way to reconstruct the 3D object from a tilt series of 2D projections. Electron tomography has been used with great success in the biological sciences for about 30 years: the 3D structure of viruses and macromolecules have been determined with remarkable accuracy using tomography based on series of bright field images. However, in materials science, for a general crystalline object, diffraction (and Fresnel) contrast prohibits the use of (coherent) BF images for electron tomographic reconstruction. Other (incoherent) signals must be used. In Cambridge we have been developing electron tomography for materials science, using STEM HAADF and inelastic EFTEM images, both predominantly incoherent signals, as the basis for the tomography tilt series. Using a variety of examples, including a number of animations, I will show how the 3D structure and composition of nanoscale objects can be revealed using electron tomography. The spatial resolution and field of view of the new technique complements perfectly the ultra-high resolution technique of atom probe tomography and the much lower resolution X-ray micro-tomography.
B. Devincre was born in France in 1965. He is married and father of two sons. He graduated from the Formation d’Ingénieur de l’Université Paris Sud Orsay, and did his PhD in Université d'Orsay. After a Post-Doc in the material department of Oxford University, he joined the Centre National de la Recherche Scientifique (CNRS) in 1994. He is currently at the Laboratoire d’Etude des Microstructures jointly run by the Office National d'Etudes et de Recherches Aérospatiales (ONERA) and CNRS. He and his collaborators developed original simulations based on Dislocation Dynamics (DD) at the meso-scale. His main interests are in linking the dynamical properties of crystal defects and the mechanical properties of material. His research is concerned with the plastic properties of pure metals, alloys and heterostructures like thin films or Metallic Matrix Composites. He has written over 40 articles. The title of his lecture is ‘What simulations of dislocation dynamics tell us that is not in textbooks?’
From Dislocation to Strain Hardening: can Discrete Dislocation Dynamics simulations make it?
The objective of the present work is to obtain a constitutive formulation con-taining a minimum number of free parameters and having a predictive value of the strain hardening properties of FCC crystals. The constitutive model used derives from an expanded form of the scalar Kocks-Mecking model. The key element is a hardening matrix, in which the matrix describing interactions between slip systems plays a major role. The early steps of modeling consisted in checking, via a com-parison between atomistic and Discrete Dislocation Dynamics (DDD) simulations, that contact reactions between dislocations can be computed at the mesoscale to a good approximation. Further, the domain of formation of junctions and locks was investigated in terms of geometrical parameters for each type of interaction. The coefficients of the interaction matrix were then determined from model DDD simulations, which led to two major results. The hierarchy of the different types of interactions shows the major role played by the collinear interaction, which surpris-ingly, has been ignored up to now. In addition, the apparent interaction coefficients were found to depend on forest density, due to line tension effects not being properly accounted for in the Taylor relation. The last step consists in setting the full con-stitutive model by integrating all the available information. Examples of predicted stress-strain curves for FCC crystals in single and multiple slip are presented and compared to experimental data. The reason why models based on uniform dislo-cation densities can reproduce single crystal behavior in monotonic deformation is discussed in the light of DDD simulations of dislocations patterning.
Max-Planck-Institut für Metallforschung, Stuttgart, Germany
Born in 1972 in Coomonte (Spain), she studied Chemistry at the Universidad Complutense and Materials Engineering at the Universidad Politécnica in Madrid (Spain). She got her PhD degree in the Instituto de Ciencia y Tecnología de Polímeros (Madrid) in 2000 working in the field of liquid crystalline polymers. She then joined the Max-Planck-Institut für Polymerforschung in Mainz (Germany) as Marie Curie Fellow and started to work in the field of surface chemistry and nanotechnology. In 2003 she moved to the Universitá degli Studi di Urbino (Italy) and since 2004 she is leading the group “Complex, Multifunctional Surfaces” within the Department “Thin Films and biological Systems” at the Max-Planck-Institute in Stuttgart (Germany). Her group is mainly engaged in developing novel synthetic approaches for manufacturing hierarchical, chemically and topographically patterned surfaces. These are based on challengi5 papers in refereed journals and 4 book chapters.
Tailored surfaces with tunable adhesion
The interaction between two bodies in close proximity is strongly influenced by the chemical nature of their outmost molecular layer and their surface topography. The external control of these factors enables fine tuning of the resulting adhesion forces. Particular interesting are surface designs which enable strong but reversible attachment, or even selective adhesion. Biology provides spectacular examples which inspire our developments, eg. the hierarchical assembly of nanosized setae found in gecko’s feet which enable their effective locomotion, or the selective attachment or cells to surfaces with particular topographies and compositions. Artificial realisation of such properties requires the combination of materials and surface chemistry with micro and nanofabrication techniques to obtain complex and responsive surface designs. Novel developments based on wavelength sensitive materials and complex 3D topographies will be presented. These will allow us to control adhesion phenomena at different levels in multiple fields of modern technologies.