Advanced Materials
Advanced materials have been key enablers of technological progress over thousands of years, lending entire ages their name. The accelerated demand for both, load-bearing and functional materials in key sectors such as energy, sustainability, construction, health, communication, infrastructure, safety and transportation is resulting in predicted production growth rates of up to 200 per cent until 2050 for many material classes. This requires not only to better understand the fundamental relationships between synthesis, manufacturing, basic mechanisms, microstructure and properties but also to discover novel materials that meet both, advanced application challenges under harsh environments.
Along these topics we work on key fields of highest relevance for society and manufacturing. Examples relate to the following fields:
- Energy (e.g., materials for a hydrogen-propelled industry, hydrogen-tolerant structural alloys, battery and catalysis materials, high temperature alloys, semiconducting materials for photovoltaics and photo-electrochemistry, fuel cell components, materials for direct solar-thermic components)
- Mobility (e.g., ductile magnesium, steels and magnets for light weight electrical and hybrid vehicles)
- Infrastructure (e.g., high strength and corrosion-resistant alloys for infrastructures, such as wind turbines and chemical infrastructures)
- Medicine & health (e.g., biomedical tribology, compliant implant alloys)
- Safety (e.g., high toughness alloys, cryogenic alloys, coatings and thin film materials, hydrogen tolerant materials).
Statistical significance in materials science is a challenge that has been trying to overcome by miniaturization as in micropillar compression. However, this process is still limited to 4-5 tests per parameter variance, i.e. Size, orientation, grain size, composition, etc. as the process of fabricating pillars and testing has to be done one by one. With this project, we aim to fabricate arrays of well-defined and located pillars of FCC metals with different stacking fault energy, that can be tested in an automated manner. With a statistically significant amount of samples tested per parameter variance, we expect to apply more complex statistical models and implement machine learning techniques to analyze this complex problem.
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European Innovation Council supports a research project led by Technical University Darmstadt with 3 million euros
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Dr. Liuliu Han heads the new research group “High-Entropy Materials”
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Max Planck scientists explore the possibilities of artificial intelligence in materials science and publish their review
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To advance the understanding of how degradation proceeds, we use the latest developments in cryo-atom probe tomography, supported by transmission-electron microscopy. The results showcase how advances in microscopy & microanalysis help bring novel insights into the ever-evolving microstructures of active materials to support the design of better materials.
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The worldwide developments of electric vehicles, as well as large-scale or grid-scale energy storage to compensate the intermittent nature of renewable energy generation has generated a surge of interest in battery technology. Understanding the factors controlling battery capacity and, critically, their degradation mechanisms to ensure long-term, sustainable and safe operation requires detailed knowledge of their microstructure and chemistry, and their evolution under operating conditions, on the nanoscale.
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Researchers use multicomponent alloys to make strong and ductile soft magnetic materials. Latest results now published in the journal Nature
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Nickel-based alloys are a particularly interesting class of materials due to their specific properties such as high-temperature strength, low-temperature ductility and toughness, oxidation resistance, hot-corrosion resistance, and weldability, becoming potential candidates for high-performance components that require corrosion resistance and good mechanical properties. This unparalleled combination of properties is achieved by adding alloying elements and changes in microstructure. This research project blended Ni-based metal welds produced by in situ alloying using the tandem GMAW process in a previous research project developed by the Welding Research and Technology Laboratory team at the Federal University of Ceará, in Brazil.
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The aim of this project is to develop novel nanostructured Fe-Co-Ti-X (X = Si, Ge, Sn) compositionally complex alloys (CCAs) with adjustable magnetic properties by tailoring microstructure and phase constituents through compositional and process tuning. The key aspect of this work is to build a fundamental understanding of the correlation between microstructure and magnetic properties by length scale bridging characterization and property determination. The ultimate goal is to establish guidelines for designing alloys with high magnetization saturation (Ms) and low coercivity (Hc), to optimize the magnetic properties of CCAs for high frequency magnetic field applications.
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In this project, links are being established between local chemical variation and the mechanical response of laser-processed metallic alloys and advanced materials.
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About 90% of all mechanical service failures are caused by fatigue. Avoiding fatigue failure requires addressing the wide knowledge gap regarding the micromechanical processes governing damage under cyclic loading, which may be fundamentally different from that under static loading. This is particularly true for deformation-induced martensitic transformation (DIMT), one of the most common strengthening mechanisms for alloys. Here, we identify two antagonistic mechanisms mediated by martensitic transformation during the fatigue process through in situ observations and demonstrate the dual role of DIMT in fatigue crack growth and its strong crack-size dependence. Our findings open up avenues for designing fatigue-resistant alloys through optimal use of DIMT. They also enable the development of physically based lifetime prediction models with higher fidelity.
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Oxides find broad applications as catalysts or in electronic components, however are generally brittle materials where dislocations are difficult to activate in the covalent rigid lattice. Here, the link between plasticity and fracture is critical for wide-scale application of functional oxide materials.
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Enabling a ‘hydrogen economy’ requires developing fuel cells satisfying economic constraints, reasonable operating costs and long-term stability. The fuel cell is an electrochemical device that converts chemical energy into electricity by recombining water from H2 and O2, allowing to generate environmentally-friendly power for e.g. cars or houses. However, upscaling anion-exchange membrane fuel cells (AEMFCs) is hindered by the slow kinetics of hydrogen oxidation reaction (HOR) at the anode.
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In this project, we work on a generic solution to design advanced high-entropy alloys (HEAs) with enhanced magnetic properties. By overturning the concept of stabilizing solid solutions in HEAs, we propose to render the massive solid solutions metastable and trigger spinodal decomposition. The motivation for starting from the HEA for this approach is to provide the chemical degrees of freedom required to tailor spinodal behaviour using multiple components.
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In this project, we work on the use of a combinatorial experimental approach to design advanced multicomponent multi-functional alloys with rapid alloy prototyping. We use rapid alloy prototyping to investigate five multicomponent Invar alloys with 5 at.% addition of Al, Cr, Cu, Mn and Si to a super Invar alloy (Fe63Ni32Co5; at.%), respectively. All the new alloys show a typical Invar effect with low TEC around room temperature.
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Laser Powder Bed Fusion (LPBF) is the most commonly used Additive Manufacturing processes. One of its biggest advantages it offers is to exploit its inherent specific process characteristics, namely the decoupling the solidification rate from the parts´volume, for novel materials with superior physical and mechanical properties. One prominet example are so called High Modulus Steels, where the combination of strong, ductile and tough metallic matrices with stiff ceramic particles allows the specific modulus (E/ρ) to be increased compared to conventional materials such as aluminum or steel, thereby reducing weight. The aim of this project is to elucidate the synthesis/microstructure/property causalities of high modulus steel fabricated with the LPBF process.
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Electro-responsive interfaces alter their properties in response to an electric potential trigger. Hence, such 'smart' interfaces offer exciting possibilities for applications in, for instance, microfluidics, separation systems, biosensors and -analytics.
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Water electrolysis has the potential to become the major technology for the production of the high amount of green hydrogen that is necessary for its widespread application in a decarbonized economy. The bottleneck of this electrochemical reaction is the anodic partial reaction, the oxygen evolution reaction (OER), which is sluggish and hence requires efficient catalysts. We use electrochemical in situ spectroscopy techniques to study this reaction in detail.
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The structure of solvent at solid-liquid interfaces influences the interactions and reactions occurring on it, which has strong impacts for applications in diverse fields, such as wetting phenomena, electrochemistry or biotechnology. We particularly try to understand the influence of nanoscale structures formed on functional interfaces on the interfacial solvent structure.
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The promising mechanical properties of metallic glasses (MG) such as high hardness, yield strength, and toughness [1] are desirable to exploit for structural applications. Monolithic MGs lack grains and grain boundaries; thus, the mechanical properties of MGs are depending on the chemistry as well as processing and testing conditions. However, despite the promising properties, catastrophic failure is often observed, especially under uniaxial tension.
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