Dusseldorf, Germany

The Max-Planck-Institut für Eisenforschung GmbH is a research institute of the Max Planck Society located in Düsseldorf.Since 1971 it is legally independent in and organized in the form of a GmbH, owned and financed equally by the Max Planck Society and the Steel Institute VDEh.It conducts basic research on advanced materials, specifically steels and related metallic alloys. Wikipedia.

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News Article | October 28, 2015
Site: news.mit.edu

The School of Engineering will add an exceptionally large class of new faculty to its ranks during the 2015-16 academic year. Eighteen engineers whose skills span scholarship, invention, innovation, and teaching will contribute to new directions in research and education across the school and to a range of labs and centers across the Institute. “We are welcoming a large and remarkably talented group of young faculty to engineering this year,” says Ian A. Waitz, dean of the School of Engineering. “They are working on an amazing range of exciting topics with direct applications to the world, from medical devices, to energy storage, to data optimization, to biofabrication strategies, and more. Their energy and enthusiasm for solving practical problems is an inspiration — to me, and to our students.” The new School of Engineering faculty members are: Michael Birnbaum will join the Department of Biological Engineering faculty as an assistant professor and become a core member of the Koch Institute for Integrative Cancer Research in January 2016. He received an BA in chemical and physical biology from Harvard University and a PhD in immunology from Stanford University, where he received the Gerald Lieberman Award, given to the school’s most outstanding medical school PhD graduate. Birnbaum’s research combines protein engineering, structural biology, and bioinformatics to understand and manipulate immune-cell responses to antigenic stimuli in cancer and infectious disease. He will teach the Department of Biological Engineering's required sophomore biological thermodynamics subject and assist in creating a new immunoengineering elective. Irmgard Bischofberger will join the faculty in the Department of Mechanical Engineering in January 2016. She received her BS, MS, and PhD in physics from the University of Fribourg in Switzerland, and is currently a postdoc at the University of Chicago. Bischofberger received a Kadanoff-Rice postdoctoral fellowship at the University of Chicago, as well as a Swiss National Science Foundation postdoctoral fellowship, and was a poster prize winner for the APS Gallery of Fluid Motion in 2012. She works in the areas of fluid dynamics and soft-matter physics, with a focus on the formation of patterns from instabilities in fluid and technological systems. In her graduate work, she studied the phase behavior and solvation properties of thermosensitive polymers. As a postdoc, she has discovered “proportional growth” — a new growth pattern that had not been previously observed despite its common occurrence in biological systems. Guy Bresler, the Bonnie and Marty (1964) Career Development Professor, joined the faculty in July in both the Department of Electrical Engineering and Computer Science and the Institute for Data, Systems, and Society; he will also be a member of the Laboratory for Information and Decision Systems. Bresler received his BS in electrical and computer engineering and an MS in mathematics from the University of Illinois at Urbana-Champaign. He received his PhD from the Department of Electrical Engineering and Computer Science at the University of California at Berkeley, and was subsequently a postdoc at MIT. He is the recipient of a National Science Foundation graduate research fellowship, a Vodafone graduate fellowship, the Barry M. Goldwater scholarship, and the Roberto Padovani Award from Qualcomm. Bresler’s research interests are at the interface of statistics, computation, and information theory. A current focus is on understanding the relationship between combinatorial structure and computational tractability of high-dimensional inference in graphical and statistical models. Betar Gallant will join the MIT faculty in January 2016 as an assistant professor of mechanical engineering. Gallant completed her BS, MS, and PhD in mechanical engineering at MIT. During her graduate studies with Professor Yang Shao-Horn, she was an National Science Foundation graduate research fellow, an MIT Martin Family Fellow and an MIT Energy Initiative Fellow. Gallant was a Kavli Nanoscience Institute Prize postdoctoral fellow at Caltech, where her research focused on tuning mechanical properties via surface chemistry control in Si-polymer structures for solar fuels applications. She will develop materials and devices for energy and environmental cleanup applications including greenhouse gas and pollutant capture and conversion, which will be informed by the understanding of chemical and electrochemical reaction pathways. She plans to utilize nanoscale insights into heat and mass transfer and energy conversion to bridge molecular control of processes with scalable environmental technologies. Ming Guo joined the faculty in the Department of Mechanical Engineering in August. He received a BE and an ME in engineering mechanics from Tsinghua University in China, and an MS and PhD from Harvard University. His doctoral research investigated the mechanical and dynamic properties of living mammalian cells, with an emphasis on intracellular mechanics and forces, the mechanics of cytoskeletal polymers, the equation of state of living cells, and the effect of cell volume and intracellular crowding on cell mechanics and gene expression. Guo discovered that there is a direct relationship between cell stiffness and volume. By varying the cell volume through a number of different techniques, he showed that the volume of cells is a much better predictor of their stiffness than any other cue, and he developed a method to measure the mechanical properties and overall motor forces inside living cells by monitoring the fluctuation of microbeads inside the cells and delineating the timescales under which the contribution of active cellular processes could be distinguished from passive mechanical properties. Jeehwan Kim joined the Department of Mechanical Engineering faculty in September. He received his BS from Hongik University in South Korea, his MS from Seoul National University, and his PhD from the University of California at Los Angeles in 2008, all in materials science. Since 2008, Kim has been a research staff member at IBM’s T.J. Watson Research Center, conducting research in photovoltaics, 2-D materials, graphene, and advanced complementary metal-oxide semiconductor (CMOS) devices. He has been named a master inventor at IBM for his prolific creativity, with over 100 patent filings in five years. Kim’s breakthrough contributions include: demonstration of peeling of large-area single-crystal graphene grown from a SiC substrate, enabling reuse of the expensive substrate; successful growth of GaN on graphene, with 25 percent lattice mismatch, demonstrating that GaN films grown from the process function well as LEDs and pointing to a new principle for growing common semiconductors for flexible electronics; and achieving high efficiency in silicon/polymer tandem solar cells and 3-D solar cells. Luqiao Liu joined MIT as an assistant professor in electrical engineering and computer science in September. He received his BS in physics from Peking University in China and his PhD in applied physics from Cornell University. He received a graduate student fellowship and the Aravind V. Subramanium T.L. Memorial Award from Cornell. Before joining MIT, Liu worked as a research staff member at IBM’s T.J. Watson Research Center. His research is in the field of spin electronics. In particular, he focuses on nanoscale materials and devices for spin logic, non-volatile memory, and microwave applications. Liu is also a recipient of the Patent Application Achievement Award from IBM. Nuno Loureiro will join the Department of Nuclear Science and Engineering faculty as an assistant professor in January 2016; he will work with the theory group of the MIT Plasma Science and Fusion Center. He earned a degree in physics engineering from Instituto Superior Técnico (IST) in Portugal, and a PhD in plasma physics from Imperial College for analytical and numerical work on the tearing instability. Loureiro held a postdoctoral position at the Princeton Plasma Physics Laboratory, a fusion research fellowship at the Culham Center for Fusion Energy in the UK, and was awarded an advanced fellowship from the Portuguese Science and Technology Foundation to work at the Institute for Plasmas and Nuclear Fusion (IPFN) at IST Lisbon. In 2012 Loureiro was appointed head of the Theory and Modeling Group at IPFN and served as an invited associate professor at the physics department of IST. His research interests cover a broad range of plasma-physics theoretical problems, including magnetic reconnection, the generation and amplification of magnetic fields, turbulent transport in magnetized plasmas, and fast-particle-driven instabilities in fusion plasmas. Loureiro is the 2015 recipient of the American Physical Society’s Thomas H. Stix Award for outstanding early career contributions to plasma physics. Robert Macfarlane, the AMAX Career Development Professor in Materials Engineering, joined the faculty as an assistant professor in the Department of Materials Science and Engineering this past summer. He earned his BA in biochemistry at Willamette University and his PhD in chemistry at Northwestern University. Macfarlane’s research is focused on developing a set of design principles for synthesizing new inorganic/organic composite materials, where nanoscale structure can be manipulated to tune the emergent physical properties of a bulk material. These structures have the potential to significantly impact energy-related research via light manipulation (e.g. photonic band gaps or plasmonic metamaterials), electronic device fabrication (e.g. semiconducting substrates or data storage devices), and environmental and medical research (e.g. hydrogels for sustained drug delivery). Karthish Manthiram will join the faculty as an assistant professor in the Department of Chemical Engineering in 2017. Currently a postdoc at Caltech, he received a bachelor’s degree in chemical engineering from Stanford University and his PhD in chemical engineering from the University of California at Berkeley. He received the Dan Cubicciotti Award of the Electrochemical Society, a Department of Energy Office of Science graduate fellowship, a Tau Beta Pi fellowship, the Mason and Marsden prize, a Dow Excellence in Teaching Award, and the Berkeley Department of Chemical and Biomolecular Engineering teaching award. As a graduate student, Manthiram developed transition-metal oxide hosts for redox-tunable plasmons and nanoparticle electrocatalysts for reducing carbon dioxide. His research program at MIT will focus on the molecular engineering of electrocatalysts for the synthesis of organic molecules, including pharmaceuticals, fuels, and commodity chemicals, using renewable feedstocks. Benedetto Marelli will join the faculty as an assistant professor in the Department of Civil and Environmental Engineering in November. He received a BE and an MS in biomedical engineering from Polytechnic University of Milan and pursued his doctoral studies in materials science and engineering at McGill University. His dissertation focused on the biomineralization of tissue-equivalent collagenous constructs and their use as rapidly-implantable osteogenic materials. As a postdoc at Tufts University, Marelli worked on the self-assembly and polymorphism of structural proteins, particularly silk fibroin. Marelli’s research at MIT will be in the area of structural biopolymers, biomineralization and self-assembly, mechanical and optoelectronic properties of natural polymers, biocomposites, additive manufacturing, and emerging technologies. By combining basic material principles with advanced fabrication techniques and additive manufacturing, he has developed new strategies to drive the self-assembly of structural biopolymers in advanced materials with unconventional forms and functions such as inkjet prints of silk fibroin that change in color in the presence of bacteria or flexible keratin-made photonic crystals. Using biofabrication strategies, his group will design bio-inspired materials that act at the biotic/abiotic interface to reduce or mitigate environmental impact. Admir Masic joined the faculty as an assistant professor in the Department of Civil and Environmental Engineering in September. He received an MS in inorganic chemistry and a PhD in physical chemistry from the University of Torino in Italy. He was a postdoc at the Max Planck Institute of Colloids and Interfaces, investigating the structural and mechanical properties of biological materials and received the Young Investigator Award from the German Research Foundation focusing on effects of water on the mechanical properties of collagen-based materials. During his PhD, Masic developed advanced characterization methodologies for the non-invasive study of deterioration pathways in ancient manuscripts, including quantifying the extent of collagen degradation in Dead Sea Scrolls. His research focus is on the development of novel, high-performance, in situ, and multi-scale characterization techniques that are able to overcome current research bottlenecks in the investigation of complex hierarchically organized materials. His work is geared towards investigating the structural and mechanical properties of biological materials, including the study of ageing and pathological processes. He is interested in the degradation and preservation of cultural artifacts, historical buildings, and civil infrastructure. Julia Ortony, the John Chipman Career Development Professor, will join the Department of Materials Science and Engineering faculty in January 2016. She earned her BS in chemistry at the University of Minnesota and her PhD in materials chemistry at the University of California at Santa Barbara. Ortony’s research interests are in two main areas: the design and optimization of soft materials with nanoscale structure for important new technologies, and the development of advanced instrumentation for measuring conformational and water dynamics analogous to molecular dynamics simulations. By combining these thrusts, technologies ranging from biomedical therapies to energy materials will be explored with special consideration paid to molecular motion. Ellen Roche will join the Department of Mechanical Engineering faculty in summer 2016, following postdoctoral training at the University of Galway; she will also be a core member of the Institute for Medical Engineering and Science. She received her BE in biomedical engineering from the National University of Ireland in Galway, and her MS in bioengineering from Trinity College in Dublin. Between these degrees, she spent five years working on medical device design for Mednova Ltd., Abbot Vascular, and Medtronic. She later received her PhD in bioengineering from Harvard University. Roche’s awards include the American Heart Association Pre-doctoral fellowship, a Fulbright international science and technology award, the Harvard Pierce fellowship for outstanding graduates, the Medtronic AVE Award, and the Ryan Hanley Award. She specializes in the design of cardiac medical devices. At Harvard, she performed research on the design, modeling, experimentation, and pre-clinical evaluation of a novel soft-robotic device that helps patients with heart failure. Her invention, the Harvard Ventricular Assist Device (HarVAD), is a soft-robotic sleeve device that goes around the heart, squeezing and twisting it to maintain the heart’s functionality. The device has no contact with blood, dramatically reducing the risks of infection or blood clotting as compared to current devices. Additionally, she worked on incorporation of biomaterials into the device to deliver regenerative therapy directly to the heart. Roche’s device, which has been validated in testing with animals, could restore normal heart function in heart failure patients. Serguei Saavedra will join the faculty in January 2016 as an assistant professor in the Department of Civil and Environmental Engineering. He received a PhD in engineering science from Oxford University. For the past four years he has been working as a postdoc at the Department of Integrative Ecology at Doñana Biological Station in Spain, at the Department of Environmental Systems Science at ETH Zurich, and at the Institute of Evolutionary Biology and Environmental Studies at the University of Zurich. Saavedra works in the area of community ecology, developing quantitative methods to understand the factors responsible for sustaining large species interaction networks. His work has revealed significant connections between the structure of these networks and the range of conditions leading to species coexistence. He has established foundations to study the response of these networks to the effects of environmental change. Saavedra’s work also has applications to sustainability in large socioeconomic systems. Justin Solomon will join the faculty as an assistant professor in the Department of Electrical Engineering and Computer Science by July 2016. He is currently a National Science Foundation mathematical sciences postdoc in applied math at Princeton University. He earned his MS and PhD in computer science from Stanford University, where he also earned a BS in mathematics and computer science. Solomon is a past recipient of the Hertz Foundation fellowship, a National Science Foundation graduate fellowship, and the National Defense science and engineering graduate fellowship. His research focuses on geometric problems appearing in shape analysis, optimization, and data processing, with application in computer graphics, medical imaging, machine learning, and other areas. He taught classes on numerical analysis, computational differential geometry, and computer science at Stanford. His textbook, "Numerical Algorithms," was released in 2015 (CRC Press). Cem Tasan will join the faculty in the Department of Materials Science and Engineering in January 2016. He holds a BS and MS from Middle East Technical University in Turkey, both in metallurgical and materials engineering, and a PhD from Eindhoven University of Technology in the Netherlands in mechanical engineering. Tasan was previously a group leader in adaptive structural materials at the Max Planck Institute for Iron Research, where he had also been a postdoc working on microplasticity at phase boundaries of multi-phase steels. He explores the boundaries of physical metallurgy, solid mechanics, and analytical microscopy in order to provide structural materials solutions to environmental challenges. His interests in micro-mechanically guided design of damage-resistant alloys and simulation-guided design of healable alloys have many applications for problems in energy and the environment. Caroline Uhler joined the Department of Electrical Engineering and Computer Science and the Institute for Data, Systems, and Society as an assistant professor in October. She holds an MS in mathematics, a BS in biology, and an MEd in high school mathematics education from the University of Zurich. She obtained her PhD in statistics, with a designated emphasis in computational and genomic biology, from the University of California at Berkeley. She is an elected member of the International Statistical Institute and received a START Award from the Austrian Science Fund. After a semester as a research fellow in the program on “Theoretical Foundations of Big Data Analysis” at the Simons Institute at Berkeley and postdoctoral positions at the Institute of Mathematics and its Applications at the University of Minnesota, and at ETH Zurich, she joined the Institute of Science and Technology Austria as an assistant professor. Her research focuses on mathematical statistics, in particular on graphical models and the use of algebraic and geometric methods in statistics, and its applications to biology.

News Article | March 2, 2017
Site: www.eurekalert.org

This year ten researchers - including four women and six men - will receive the Heinz Maier-Leibnitz Prize, the most important award for early career researchers in Germany. The recipients were chosen by a selection committee in Bonn appointed by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) and the Federal Ministry of Education and Research (BMBF). The prizewinners will each be presented with the €20,000 prize on 3 May in Berlin. This will be followed by a celebration of the 40th anniversary of the Heinz Maier-Leibnitz Prize. The Heinz Maier-Leibnitz Prize has been awarded annually to outstanding early career researchers since 1977 - as both recognition and an incentive to continue pursuing a path of academic excellence. Since 1980 it has been named after the atomic physicist and former DFG President Heinz Maier-Leibnitz, during whose period in office (1973-1979) it was first awarded. The Heinz Maier-Leibnitz Prize is regarded not just as the most important award for early career researchers in Germany. In a survey carried out by "bild der wissenschaft" magazine, the major research organisations voted the Heinz Maier-Leibnitz Prize the third most important research prize in Germany - after the Gottfried Wilhelm Leibniz Prize, presented by the DFG, and the Deutscher Zukunftspreis, awarded by the German President. A total of 154 researchers representing all research areas were nominated for this year's prize; 14 of the nominees were then shortlisted. "We were delighted at the sheer number of nominations received in the prize's anniversary year," said the chair of the selection committee, mathematician and DFG Vice President Prof. Dr. Marlis Hochbruck. "The ten recipients are an outstanding example of the high standard of academic quality and qualification of many young researchers in Germany." In his research, Andreas Geiger deals with the broad field of computer vision, in which he has already achieved international renown. His work combines machine vision and robotics. Geiger's main aim is to understand the basic principles of autonomous intelligent systems, especially in the area of autonomous driving. His work is therefore highly relevant not only socially, but also economically. Many of the algorithms he has developed are now being used by research teams and companies throughout the world and his scientific papers have already won multiple awards. Since 2016 Geiger has led the independent Max Planck research group 'Autonomous Machine Vision'. In the same year he was offered an interim professorship at ETH Zurich, in one of the world's biggest and most renowned labs for computer vision. As a postdoctoral researcher Christian Gross was involved in the pioneering development of microscopes for the observation of single atoms in optical grids. This enabled him to model a wide range of quantum systems experimentally and answer questions at the boundary of statistical physics and quantum mechanics. Gross achieved important results relating to phase transitions, magnetic correlations and non-equilibrium systems. Another key area of his work is the physics of Rydberg superatoms, with which he has generated new types of quantum crystals, for example. In 2015 Gross received an ERC Starting Grant for his project 'Rydberg-dressed Quantum Many-Body Systems' in order to advance research with his team that could pave the way for the design of quantum magnets. How do our attitudes influence our choices and ability to make moral judgements? When do personal experiences turn into prejudices? Mandy Hütter seeks answers to questions like these. She demonstrates that not all attitudes are the result of conscious learning processes and that moral judgements are also dependent on 'situational cues'. Hütter has published her results in internationally respected journals. In clinical practice they have proved useful in interventional approaches for phobias and are also creating new insights in the area of social prejudices, the study of democratic processes and the 'wisdom of the many'. Hütter, who also regularly presents her work to the general public, is a junior professor and the leader of the Social and Organisational Psychology group at the University of Tübingen. She also leads an Emmy Noether independent junior research group. Difficulty dealing with emotions and regulating them through changed evaluation is not limited to people with a range of psychological disorders: the same applies to healthy people who have an increased risk of developing such disorders. This is one finding from the work of psychologist Philipp Kanske, who studies the influence of emotions on the way we think and perceive things. He combines basic research with clinical studies, which enables him to adopt an original perspective on the topic at various psychological levels. With approximately 50 publications to date, Kanske has already had a notable impact on clinical-psychological neuroscience. In 2015 he was appointed to the Junge Akademie of the Berlin-Brandenburg Academy of Sciences and Humanities and the German National Academy of Sciences Leopoldina. At the Max Planck Institute in Leipzig he leads the Research Unit 'Psychopathology of the Social Brain'. Since 2013 Kirchlechner has led the working group 'Nano-/Micromechanics of Materials' at the Max Planck Institute for Iron Research in Düsseldorf, where he and his team study the deformation and failure of materials in mesoscopic dimensions. The team's combination of micromechanical experiments and innovative methods for the characterisation of structures - including the so-called micro-Laue method - is unique. One measurement method co-developed by Kirchlechner makes it possible to investigate the influence of atomic defects on specific material properties. It therefore provides answers to key questions in materials science and engineering, specifically the mechanisms of fine grain hardening and the formation of dislocation structures during fatigue processes. Kirchlechner is already considered an internationally recognised expert in micromechanical experiments on synchrotrons. Olivier Namur collected a number of awards while still a student in Belgium and now publishes in his specialist field - the study of volcanic systems and magmatic processes on Earth, the Moon and Mercury - with remarkable impact in international bodies. Namur has developed thermodynamic models not only of the crystallization of magmas, but also of their physical properties. His research has also resulted in new experimental high-pressure, high-temperature methods. Another focus of Namur's research is the investigation and modelling of the textures of minerals in igneous rock, which contain information about the transport of materials and temporal processes in the Earth's deep crust. In recent years this has included crystal mushes, magmas with a very high crystalline content, which reach the surface as fragments due to eruptions and could provide clues as to the structure of the Earth's lower crust. Ute Scholl's field is the study of hypertonia, especially (pre)disposition to this condition due to genetic defects in ion channels and ion transporters. After writing her doctoral thesis on CIC-K chloride channels, which produced a number of highly regarded publications, in her postdoctoral phase she became the first researcher to describe a new syndrome and its genetic basis, which is associated with epilepsy, inner ear hearing loss, ataxia and renal salt loss. Scholl's research has made a significant contribution to the understanding of the hormonal degeneration processes that lead to secondary hypertonia with consequences such as cardiac circulatory disorders or stroke. Since 2014 Scholl has been a junior professor in Experimental Nephrology and Hypertensiology at the University of Düsseldorf. In 2016 she served as deputy spokesperson of the Junges Kolleg of the North Rhine-Westphalian Academy of Sciences, Humanities and the Arts. Her work has won numerous awards, including the Walter Clawiter Prize and the Ingrid zu Solms Research Prize. With his dissertation 'Verisimilitudo. Die epistemologischen Voraussetzungen der Gotteslehre Abaelards' and his habilitation thesis 'Theologie aus anthropologischer Ansicht. Der Entwurf Franz Oberthürs (1745-1831)', within a few years Michael Seewald established himself as an expert in dogmatics and ecumenical theology. The former won the Cardinal Wetter Prize of the Catholic Academy in Bavaria, while the latter was awarded the Karl Rahner Prize presented by the University of Innsbruck. Through his habilitation thesis, in particular, Seewald presented a fundamental work on the reception of the European Enlightenment in the environment of Catholic dogmatics, which, through an individual person, also sheds new light on the general relationship between the Catholic Church and modernity. This fills an important gap in research. Since January 2016, Seewald has taught as a private lecturer in dogmatics and ecumenical theology at LMU Munich. Marion Silies began to study the motion perception of Drosophila as a postdoctoral researcher at Stanford University. Since 2014 she has led the Emmy Noether independent junior research group 'The Cellular and Molecular Basis of Motion Perception' at the University of Göttingen. In this group she investigates the outstanding question of how neural networks perform critical calculation operations and how sensory systems use these calculations to extract information from the environment and control behaviour. Among the tools Silies uses is a genetic 'toolbox', established by her and now used by countless laboratories worldwide. With this toolbox researchers can manipulate neural function in specific cells and thus identify the neural networks of motion perception. Silies has won multiple awards for her work. In 2016 she received an ERC Starting Grant for her project 'MicroCyFly'. Within comparative literature, Evi Zemanek's fields of research range from antiquity to the present day. In the field of cultural ecology and 'ecocriticism', which investigates literary texts in the context of ecological aspects, she is considered a pioneer in German-language literature studies. In 2012 she established the DFG early career researcher network 'Ethics and Aesthetics of Literary Representations of Ecological Transformations', on behalf of which she organised six groundbreaking conferences. Since her dissertation 'Das Gesicht im Gedicht' (2010), intermediality research, especially the relationship of literature to painting, photography and architecture, has been another key aspect of her scholarly work. Zemanek is a junior professor of Modern German Literature and Intermediality at the University of Freiburg. In the winter semester 2016/2017 she will serve as an interim professor in the Institute of Media and Cultural Studies. The 2017 Heinz Maier-Leibnitz Prize award ceremony, followed by a celebratory event, will be held on 3 May at 6 pm at the Berlin-Brandenburg Academy of Sciences and Humanities, Markgrafenstraße 38, 10117 Berlin. Representatives from the media are cordially invited to attend the award ceremony. Please register in advance with the DFG Press and Public Relations Office, tel. +49 228 885-2109, presse@dfg.de. More information about the prize and previous winners is available at: http://www.

Kim J.,Max Planck Institute for Iron Research | Estrin Y.,Monash University | De Cooman B.C.,Pohang University of Science and Technology
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2013

High Mn steels exhibit an exceptional combination of high strength and large ductility owing to their high strain-hardening rate during deformation. The addition of Al is needed to improve the mechanical performance of TWIP steel by means of the control of the stacking fault energy. In this study, a constitutive modeling approach, which can describe the strain-hardening behavior and the effect of Al on the mechanical properties, was used. In order to understand the deformation behavior of Fe18Mn0.6C and Fe18Mn0.6C1.5Al TWIP steels, a comparative study of the microstructural evolution was conducted by means of transmission electron microscopy and electron backscatter diffraction. The microstructure analysis focused on dislocations, stacking faults, mechanical twins as these are the defects controlling the strain-hardening behavior of TWIP steels. A comparison of the strain-hardening behavior of Fe18Mn0.6C and Fe18Mn0.6C1.5Al TWIP steels was made in terms of a dislocation density-based constitutive model that goes back to the Kubin-Estrin model. The densities of mobile and forest dislocations are coupled in order to account for the interaction between the two dislocation populations during straining. The model was used to estimate the contribution of dynamic strain aging to the flow stress. As deformation twinning occurred only in a subset of the grains, the grain population was subdivided into twinned grains and twin-free grains. Different constitutive equations were used for the two families of grains. The analysis revealed that (i) the grain size and dynamic recovery effects determine the strain-hardening behavior of the twin-free grains, (ii) the deformation twins, which act as effective barriers to dislocation motion, are the predominant elements of the microstructure that governs the strain hardening of the twinned grains, (iii) the DSA contribution to strain hardening of TWIP steel is only minor. © 2013 The Minerals, Metals & Materials Society and ASM International.

Sandlobes S.,Max Planck Institute for Iron Research | Zaefferer S.,Max Planck Institute for Iron Research | Schestakow I.,Max Planck Institute for Iron Research | Yi S.,Max Planck Innovation | Gonzalez-Martinez R.,Max Planck Innovation
Acta Materialia | Year: 2011

Mg-Y alloys show significantly enhanced room temperature ductility compared to pure Mg and other classical Mg wrought alloys. The presented study focuses on understanding the mechanisms for this ductility improvement by microstructure analysis, texture analysis and slip trace analysis based on electron backscatter diffraction and transmission electron microscopy. As expected, pure Mg mainly deforms by 〈a〉 basal slip and tensile twinning. In contrast, Mg-Y shows a high activity of compression twinning, secondary twinning and pyramidal 〈c + a〉 slip. These additional deformation modes cause a homogeneous deformation with a weaker basal texture, more balanced work hardening and enhanced ductility. Additionally, in Mg-Y shear bands are much more frequent and carry less strain than those in pure Mg. As a consequence, failure in shear bands occurs at significantly higher strain. The experimental results are discussed focusing on the mechanisms effecting the observed high activation of pyramidal deformation modes in Mg-Y. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fernandez A.,IMDEA Madrid Institute for Advanced Studies | Jerusalem A.,University of Oxford | Gutierrez-Urrutia I.,Max Planck Institute for Iron Research | Perez-Prado M.T.,IMDEA Madrid Institute for Advanced Studies
Acta Materialia | Year: 2013

The effect of grain boundary (GB) misorientation (θ) on twinning in a Mg AZ31 alloy is investigated using a three-dimensional (3-D) experimental and modeling approach, in which 3-D electron backscattered diffraction is performed in a volume consisting of a central grain, favorably oriented for twinning, and surrounded by three boundaries, with θ ranging from 15 to 64. This study corroborates previous observations that twin nucleation and propagation are favored at low θ. Furthermore, it reveals that non-Schmid effects, such as the activation of low Schmid factor (SF) variants or of double tensile twins, are absent in the vicinity of low misorientation boundaries and that they become more abundant as θ increases. The 3-D morphology of individual twin variants is found to be related to their SF. High SF variants have well-established plate morphology, while low SF variants adopt irregular shapes. A crystal plasticity continuum model recently proposed by the authors is used in a very high intragrain resolution and large-scale finite element polycrystalline aggregate model of the experimental specimen. This model is shown to successfully capture the influence of θ on twin propagation and variant selection. It ultimately predicts (i) a rise in local non-basal slip with increasing θ, (ii) that low θ GB favor twin nucleation by non-Schmid stress concentrations, but that propagation is immediately accommodated by the macroscopic stress, and (iii) that high θ GB are not favorable twin nucleation sites, despite having high von Mises stress concentrations. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

News Article | October 23, 2015
Site: news.mit.edu

Excess surface energy from unsatisfied bonds is a significant driver of dimensional changes in thin-film materials, whether formation of holes, contracting edges, or run-away corners. In general, this break-up of a material is known as dewetting. Recent MIT graduate Rachel V. Zucker, who received her PhD on June 5, has developed a range of mathematical solutions to explain various dewetting phenomena in solid films. Working with collaborators at MIT as well as in Germany and Italy, Zucker, 28, developed a model for calculating fully-faceted edge retraction in two dimensions, but she says the crown jewel of her work is a phase field approach that provides a general method to simulate dewetting. Thin-film materials range from about 1 micrometer (micron) down to just a few nanometers in thickness. Nanometer-scale films are the basic building blocks for circuit boards in electronic and electrochemical devices, and are patterned into wires, transistors, and other components. Zucker developed models for what happens to thin films over time. "They have a lot of surface area compared to their volume, just because they are so thin, especially in one dimension, and so that can actually amount to a huge driving force for the thin film to change its shape," she says. At MIT, Zucker was co-advised by professors W. Craig Carter and Carl V. Thompson. With dewetting, Zucker tackled one of the hard problems in materials science, Carter explains, especially with the addition of anistropic surface tension. "Equations start looking very complicated and the methods that you would you use to solve those equations start becoming more and more obscure. And so as you go down this path, you're going into terra incognita. How do you go about solving these problems?" Dewetting of solid films looks like dewetting of a liquid — for example, water beading up on a windshield — but the material stays solid during this process. Solid-state dewetting can happen at temperatures well below the melting temperatures of the material when the film is very thin, and especially when it is patterned to make very small features like wires in integrated circuits. "Solid-state dewetting is getting to be more and more of a problem as we make things with smaller and smaller features," Thompson says. Zucker studied both isotropic materials, which exhibit the same properties in all directions, and anisotropic materials, which show different properties in different directions. Isotropic materials, which are usually glassy, are good materials to develop models, but are rarely used as engineering materials, she says. Common engineering materials such as metal, ceramic, or single-crystal thin films are usually anisotropic materials. Zucker carried out stability analyses to understand the onset of the sometimes beautiful morphologies seen in experiments. "The big takeaway is: One, we can write down formulation of this problem; two, we can implement a numerical method to construct the solutions; three, we can make a direct comparison to experiments; and that strikes me as what a thesis should be — the complete thing — formulation, solution, comparison, conclusion," Carter says. Zucker defended her thesis, "Capillary-Driven Shape Evolution in Solid-State Micro- and Nano-Scale Systems," on April 13. She says her breakthrough came in creating a geometric model of edge retraction. "I knew I wanted to do these stability analyses; I knew I wanted to understand the fingering instability and the corner instability, the Rayleigh instability, but I didn't know where to begin," Zucker says. When she recognized that she could generalize this geometry and use Wolfram Mathematica to handle the algebra, she was able to apply it not only to edge retraction, but also to extend it to the fingering instability and corner instability. "I'd say that was a useful insight," she adds, but notes that it came not while working, but while running during a Christmas break. "Then all of sudden it hit me," she explains. For her doctoral research, Zucker examined film break-up during dewetting based on capillary action for edge retraction and pinch-off, the fingering instability, the Rayleigh instability, and the corner instability. This capillary action occurs most dramatically at a region known as the triple line, where three phases meet, commonly the substrate, film being deposited, and atmosphere. The exception, which cannot be explained by capillary action alone, is hole formation, Zucker notes. With her phase field approach, Zucker says, "I don't have to make simplifying assumptions. I don't have to simplify the geometry, for example. It just treats the full problem. There have been I would say two previous simulation attempts, but ours is the first code that I would say is actually useful, because it's fast enough that it will run in a reasonable amount of time on a reasonable number of computer cores. So we can actually do science with it." Simulations that used to take a month on previous code can be reduced to about three days running her simulation, she explains. "Rachel made very significant advances in our understanding of the fingering instability that develops along the edges of films as they undergo solid-state dewetting," Thompson says. "While people had speculated that the rims that form on these edges undergo a Rayleigh-like instability that leads to fingering, Rachel showed that a new instability she discovered, due to 'divergent retraction,' plays a dominant role. This allows better predictions of the length scales of structures that result from the dewetting process, and for how films might be modified to obtain structures with desired characteristics. "Rachel also provided new and better explanations of the mechanisms that cause sharp corners in the edge of a retracting hole to run out ahead of other parts of the edge. Speculations in the literature focused on the role of long-range diffusion of material away from the corner, but Rachel showed that all the mass that is redistributed at the retracting tip of a corner is consumed locally in extending the length of the adjacent edges. This provided a fundamentally new way of thinking about evolution of the shapes of holes, and how that evolution might be controlled," Thompson explains. Zucker spent an extensive amount of time working on her doctorate in Germany, where she was hosted by Professor Christina Scheu, of the Max Planck Institute for Iron Research in Düsseldorf and the Ludwig-Maximilians University in Munich. Zucker spent about nine months in Munich followed by nine months in Düsseldorf. Zucker credits much of the code development work for phase field simulations of dewetting to Professor Axel Voigt at the Technical University of Dresden in Germany, and postdoc Rainer Backofen. She also credits Professor Francesco Montalenti at the University of Milan-Bicocca in Italy, postdoc Roberto Bergamaschini, and PhD student Marco Salvalaglio with helping her learn how to use the code. While in Germany, she has also been working on microstructural optimization for energy materials. "I wanted to work on these surface-energy-driven problems because they are so fundamental to materials science," Zucker explains. Carter connected Zucker with Thompson, whose group had been doing experiments focused on developing a better understanding of solid-state dewetting, both in order to prevent or suppress it in some cases, and also to develop new ways to control it to make specific patterns in other cases. Zucker tackled various irregularities in thin-film formation, including Rayleigh instabilities, edge retraction, fingering, and corner instabilities. In the Rayleigh instability, for example, a cylinder of materials breaks up into isolated particles. The Rayleigh instability is a classical result that is now 137 years old. "Otherwise the other instabilities involved in dewetting of films haven't really been studied," Zucker says of her work. "I've done a lot of linear instability analyses to understand what wavelengths are going to be showing up in these instabilities, what length scales are we talking about and how that is connected to the film thickness." The model Zucker developed for two-dimensional edge retraction for highly anisotropic, fully-faceted thin films was published in 2013 in the journal Comptes Rendus Physique ("Proceedings of Physics"). Zucker's model was largely in accordance with experiments carried out by Alan Gye Hyun Kim in Thompson's group on edge retraction of 130-nm-thick, single-crystal nickel films on magnesium oxide (MgO). Zucker was also a co-author of Kim's 2013 experimental paper in the Journal of Applied Physics. Both experiments and model showed rims form as the edges retract. In a fully-faceted film, the crystal material has facets similar to a jewel-cut diamond. Zucker, who studied four different orientations of the crystal structure, found that the diffusivity on the facet at the top of the rim has the largest influence on retraction, followed by influences from the other facets of the material. Both experiments and the model showed retraction distances varying by up to two times, depending on the edge orientation. The model was in closest agreement with experimental results for an (001) film with an edge retracting in the (100) direction — varying by just 10 percent. However, Zucker's paper noted, the model over-estimated retraction distance for (001) film retracting in the (110) direction and underestimated distance for an (011) film retracting in the (110) direction. Zucker suggests the discrepancy between model and experiment could be accounted for by error in reported values of diffusivities for nickel facets and uncertainty about interfacial energy between the nickel film and magnesium oxide substrate. "The major factors which determine the retraction rate of a thin film, according to this model, are: the film thickness, the atomic diffusivity on the top facet and the angled facet, the equivalent contact angle of the film on the substrate, and the absolute value of the surface energy. The edge retraction distance scales with the film thickness h as h1/2," Zucker reported in "A model for solid-state dewetting of a fully-faceted thin film." In a 2012 paper, Zucker presented a new method for finding the equilibrium shapes of faceted particles attached to a deformable surface. With Carter and three others, Zucker presented a suite of software tools to calculate these equilibrium shapes as well as for isolated particles and for particles attached to rigid interfaces. Their open-source code, WulffMaker, is available as a Wolfram computable document format file or a Mathematica notebook. It is useful for modeling Wulff shapes for engineering materials such as alumina, as well as more complicated Winterbottom and double Winterbottom shapes. While the Wulff method models the simplest case of a uniform shape attaching to a level surface, the software also incorporates a new algorithm for calculating interfaces with more complicated angles of attachment and attachment to rigid substrates. The tool could be useful for analyzing electronic and optical devices produced from materials deposited on a substrate. The software combines interface energy data with geometric shape data and so can be used in reverse to calculate interface energy for abutting materials from experimentally obtained geometric data. "This tool introduces a new computational method for finding shapes of minimal interface energy. It also helps to build intuition about the macroscopic properties of interfaces and their interactions, and aids in the quantitative measurement of interface energy densities, given a geometry. Properties such as the equivalent wetting angle, particle contact area, total energies, and distortions to the interface surrounding the particle are displayed by the software to enable further insight and analysis," Zucker wrote in her thesis. Besides her work in creating computerized models for thin film deformation, Zucker has been working with Carter on a new format to teach materials science that Carter calls proctored scaffolding. Unlike online instruction that allows students to passively consume information by watching videos or reading text, their approach is interactive and requires critical thinking. "The student can't just skate by without doing that critical thinking," Zucker explains. Zucker used the method, which integrates the Wolfram Language, to teach 3.016 (Mathematics for Materials Science and Engineers) two years ago while Carter was on sabbatical. She has traveled internationally with Carter to demonstrate these materials science master classes. They also made a user interface tool for content developers, to make it easier for other instructors to create Mathematica notebooks. A native of North Carolina, Zucker completed her bachelor's at MIT in 2009, receiving an outstanding senior award from the Department of Materials Science and Engineering. Zucker starts a three-year postdoctoral fellowship in July at the Miller Institute at the University of California at Berkeley. She will be affiliated with both the mathematics and materials science departments. "I think ever since I was born I was going to be a professor," Zucker says.

Zaefferer S.,Max Planck Institute for Iron Research | Elhami N.-N.,Max Planck Institute for Iron Research
Acta Materialia | Year: 2014

Electron channelling contrast imaging (ECCI) is a powerful technique for observing crystal defects, such as dislocations, stacking faults, twins and grain boundaries in the scanning electron microscope. Electron channelling contrast (ECC) is strongest when the primary electron beam excites so called two-beam diffraction conditions in the crystal. In the present approach this is achieved, by a combination of crystal orientation measurement using electron backscatter diffraction (EBSD) and simulation of electron channelling patterns. From the latter, the crystal is rotated such that two-beam diffraction conditions are achieved. This technique is called "ECCI under controlled diffraction conditions" or cECCI. Following an extensive literature review, this paper presents a simple, yet instructive and demonstrative treatment of the theory of ECC of lattice defects based on Bloch wave theory using a two-beam approach. This is followed by a discussion of technical issues associated with an ideal ECC set-up such as optimum detector position and microscope conditions. Subsequently, the appearance of different types of lattice defects under ECCI conditions; namely of dislocations, stacking faults, slip lines, and nanotwins, is discussed in detail. It is shown how different types of defects are distinguished and which type of crystallographic information can be extracted from such observations. Finally, the limits of the technique, particularly in terms of spatial resolution and depth of visibility are discussed and a comparison with the EBSD and transmission electron microscopy techniques with respect to imaging lattice defects is provided. In contrast to many investigations recently published in the literature, the current paper focuses on 'true' backscattering, i.e. on a signal that is recorded with a conventional backscatter detector positioned below the pole piece, and not on forward scattering, where the signal is recorded on a detector usually positioned below the EBSD detector. This has significant advantages in terms of spatial resolution and contrast, which are discussed in the text. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Davut K.,Max Planck Institute for Iron Research | Zaefferer S.,Max Planck Institute for Iron Research
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

The aim of this article is to discuss the representativeness of electron backscatter diffraction (EBSD) mapping data for phase fraction determination in multiphase materials. Particular attention is paid to the effect of step size and scanned area. The experimental investigations were carried out on a low-alloyed steel with transformation induced plasticity (TRIP) that shows a relatively heterogeneous distribution of residual austenite in a ferrite matrix. EBSD scans of various area sizes and step sizes were carried out and analyzed with respect to the determined austenite phase fraction. The step size has only an indirect influence on the results, as it determines the size of the investigated area if the number of measurement points is kept constant. Based on the experimental results, the optimum sampling conditions in terms of analyzed area size and the number of measurement points were determined. These values were compared with values obtained from Cochran's formula, which allows calculation of sampling sizes for predefined levels of precision and confidence. A significant deviation of experimental from theoretical optimum sample sizes was found. This deviation is, for the most part, a result of the heterogeneous distribution of the austenite phase. Depending on grain size and volume fraction of the second phase, the false assignment of phases at grain boundaries also may introduce a significant error. A general formula is introduced that allows estimation of the error caused by these parameters. Finally, a new measurement scheme is proposed that allows improvement of reliability and representativeness of EBSD-based phase determination without large sacrifices in measurement time or data set sizes. © 2010 The Minerals, Metals & Materials Society and ASM International.

Zaefferer S.,Max Planck Institute for Iron Research
Crystal Research and Technology | Year: 2011

Orientation microscopy (OM) refers to techniques for reconstruction of microstructures based on the spatially resolved measurement of individual crystallographic phases and orientations. This review gives an overview on different techniques of OM in the scanning and transmission electron mi-croscope. All rely on the automated evaluation of electron diffraction patterns. The most popular technique is based on electron backscatter diffraction (EBSD) in the SEM. In the TEM several techniques are available which are based on either Kikuchi diffraction patterns, spot diffraction patterns with and without electron precession, or reconstructed spot diffraction patterns. Each technique is introduced in detail. Subsequently the techniques are critically compared with respect to their spatial and angular resolution, their robustness in terms of orientation determination and questions of practical applicability for materials science. One point discussed in detail is the spatial resolution. It is shown that the spatial resolution, i.e. the volume from which the diffraction information is generated, is not very different for the SEM and TEM techniques. For this and other reasons we argue that the EBSD technique is in many cases the best suited method for OM. In those cases where it is not (e.g. investigations on truly nanocrystal-line materials, beam sensitive samples) it is the spot diffraction method combined with electron precession and template matching for orientation determination which offers the best resolution and robustness. The Kikuchi pattern technique in the TEM is only reasonably used when highest angular resolution is to be achieved, e.g. for lattice constant determination. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Home > Press > Materials scientists at FAU reconstruct turbine material atom by atom in computer simulations Abstract: Superalloys – materials made of a combination of nickel, aluminium and other elements such as rhenium – are essential for manufacturing turbine blades in jet engines, for example. They ensure that the turbines remain stable even at extremely high temperatures close to their melting point – crucial under the immense strain caused by centrifugal force. For this reason, materials scientists are constantly working on making superalloys even better. A team of researchers at FAU led by Prof. Dr. Erik Bitzek has now succeeded in reconstructing the atomic structure of a nickel-based superalloy so exactly using computer simulations that the simulations are able to reproduce and explain the actual deformation process in the real material structure. Until now, researchers have only ever been able to work with idealised structures in their simulations. The Erlangen-based researchers are now able to accurately simulate how certain linear crystallographic defects (known as dislocations) in the nickel-based superalloy move when forces are exerted on the turbine blade, causing deformation of the material. In order to achieve this, Prof. Bitzek and his team began by using data gathered by their colleagues at the Max Planck Institute for Iron Research using an atom probe. Measurements taken using an atom probe provide 3D information about the atomic structure of an alloy but are only able to localise around two thirds of the atoms present. However, the researchers were able to use the data collected in this way with a new software called nanoSCULPT, developed at their institute, to create atomic models that simulate not only the exact nature of the precipitates – particles with a different crystallographic structure and composition that are embedded in the crystal – but also the nickel and aluminium atoms in the alloy. This allowed them to correctly simulate the precipitates around existing networks of dislocations and to accurately reproduce the dislocation structures that a team led by fellow FAU researcher Prof. Dr. Erdmann Spiecker had previously observed using a high-resolution transmission electron microscope. Prof. Bitzek and his team then used high performance computers at FAU to simulate tensile tests on these microstructures, which are made up of over 14 million atoms. This meant that, for the first time, they were able to show in detail on the atomic scale how the precipitates and the surrounding network of dislocations restrict the movement of dislocations, increasing the strength of the material. The findings could now be used as a basis for developing superalloys that can withstand even higher temperatures, which would reduce the fuel consumption – and therefore the CO2 emissions – of jet engines. A total of nine groups of materials scientists at FAU are working towards this goal in collaboration with colleagues at Ruhr-Universität Bochum and other research institutions as part of the Collaborative Research Centre/Transregio 103 ‘From atom to turbine blade’ which, it was recently announced, is being funded by the German Research Foundation (DFG) for a further four years with 15 millions euros. The FAU team’s results were published in a study in the journal Acta Materialia which is now one of the top ten most-read articles. The study was also mentioned in the latest bulletin of the Materials Research Society. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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