TY - JOUR A1 - Das, A. A1 - Ott, C. A1 - Pechimuthu, Dinesh A1 - Moosavi, Robabeh A1 - Stoica, M. A1 - Derlet, P. M. A1 - Maaß, Robert T1 - Shear-band cavitation determines the shape of the stress-strain curve of metallic glasses N2 - Metallic glasses are known to have a remarkably robust yield strength, admitting Weibull moduli as high as for crystalline engineering alloys. However, their postyielding behavior is strongly varying, with large scatter in both flow stress levels and strains at failure. Using x-ray tomography, we reveal how a strain-dependent internal evolution of shear-band cavities underlies this unpredictable postyielding response.We demonstrate how macroscopic strain softening coincides with the first detection of internal shear-band cavitation. Cavity growth during plastic flow is found to follow a power law, which yields a fractal dimension and a roughness exponent in excellent agreement with self-similar surface properties obtained after fracture. These findings demonstrate how internal microcracking coexists with shear-band plasticity along the plastic part of a stress-strain curve, rationalizing the large variability of plastic flow behavior seen for metallic glasses. KW - Shear-band cavitation KW - Metallic glasses PY - 2023 DO - https://doi.org/10.1103/PhysRevMaterials.7.023602 SN - 2475-9953 VL - 7 IS - 2 SP - 1 EP - 11 PB - American Physical Society AN - OPUS4-57042 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Riechers, Birte A1 - Maaß, Robert T1 - nanoindentation data associated with the publication "On the elastic microstructure of bulk metallic glasses" in Materials&Design 2023 N2 - This dataset consists of indentation data measured with a conospherical tip in a Hysitron-Bruker TI980 Nanoindenter on the surface of a <100> Silicon wafer and a polished cross-sectional cut of a Zr65Cu25Al10 bulk metallic glass. It is associated with the following publication: Birte Riechers, Catherine Ott, Saurabh Mohan Das, Christian H. Liebscher, Konrad Samwer, Peter M. Derlet and Robert Maass "On the elastic microstructure of bulk metallic glasses" Materials and Design xxx, (2023) 111929. https://doi.org/10.1016/j.matdes.2023.111929 All experimental information can be found in this paper and in the accompanying supplementary information. This electronic version of the data was published on the "Zenodo Data repository" found at http://zenodo.org/deposit in the community "Bundesanstalt fuer Materialforschung und -pruefung (BAM)". The authors have copyright to these data. You are welcome to use the data for further analysis, but are requested to cite the original publication whenever use is made of the data in publications, presentations, etc. Any questions regarding the data can be addressed to birte.riechers@bam.de who would also appreciate a note if you find the data useful. KW - Metallic glasses KW - Nanoindentation KW - Elastic microstructure PY - 2023 DO - https://doi.org/10.5281/zenodo.7818224 PB - Zenodo CY - Geneva AN - OPUS4-57352 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maaß, Robert T1 - Intermittent cluster dynamics and temporal fractional diffusion in a bulk metallic glass N2 - Inspired by the ability to track atomic-scale dynamics with x-ray photon correlation spectroscopy (XPCS)1 and recent results of long-term atomistic simulations on material transport2, we reveal here an unprecedented spectrum of short- and long-term relaxation dynamics. Tracked along a 300 000 s long isotherm at 0.98Tg, a Zr-based bulk metallic glass exhibits temporal fluctuations that persist throughout the entire isotherm, demonstrating a continuous heterogeneous dynamics at the probed length scale. In concert with microsecond molecular dynamic simulations, we identify intermittent cluster dynamics as the origin for temporal signatures in the corresponding intensity cross-correlations. Despite temporally heterogeneous aging, the Kohlrausch-Williams-Watts functions is well suited to capture the average intermediate relaxation time regime, but at very long time scales an asymptotic power-law better describes the data. This indicates anomalous diffusion and gives overall strong evidence for temporal fractional diffusion in metallic glasses. We discuss these results in terms of the underlying structural fast and slow relaxation modes and their manifestation in the temporal form of the structural decorrelations. T2 - 9th IDMRCS CY - Chiba, Japan DA - 12.08.2023 KW - Metallic glass KW - Transport KW - Structure KW - Dynamics PY - 2023 AN - OPUS4-60696 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maaß, Robert T1 - Cluster dynamics and anomalous transport in metallic glasses N2 - Quenching a metallic liquid sufficiently fast can give rise to an amorphous solid, typically referred to as a metallic glass. This out-of-equilibrium material has a long suite of remarkable mechanical and physical properties but suffers from property deterioration via structural relaxation. As a function of time, relaxation may indeed constitute significant threads to safe applications. Consequently, relaxation of glasses has a long history across different amorphous materials and typical characterization methods promote a picture of gradually evolving and smooth relaxation, as for example obtained from mechanical spectroscopy. However, the true structural dynamics and underlying mechanisms remain far from understood and have hampered a physically informed atomic-scale picture of transport and physical aging of glasses. Here we exploit the ability to track atomic-scale dynamics with x-ray photon correlation spectroscopy (XPCS) and resolve an unprecedented spectrum of short- and long-term relaxation time scales in metallic glasses. Conducted across temperatures and under the application of stress, the results reveal anything else than smooth aging and gradual energy minimization. In fact, temporal fluctuations persist throughout isothermal conditions over several hundred thousand of seconds, demonstrating heterogeneous dynamics at the atomic scale. In concert with microsecond molecular dynamic simulations, we identify possible mechanisms of correlated atomic-scale dynamics that can underly the temporal fluctuations and structural decorrelations. Despite temporally heterogeneous, the Kohlrausch-Williams-Watts functions is well suited to capture the average intermediate relaxation time regime, but at very long time scales an asymptotic power-law emerges. This indicates anomalous diffusion and gives overall strong evidence for temporal fractional diffusion in metallic glasses. We discuss these results in terms of the structural fast and slow relaxation modes as well as a true microstructure in metallic glasses. T2 - Department Seminar OSU 2023 CY - Columbus, OH, USA DA - 22.09.2023 KW - Metallic glass KW - Transport KW - Structure KW - Dynamics PY - 2023 AN - OPUS4-60699 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maaß, Robert T1 - On an unusual career path and unusual transport in metallic glasses N2 - Planning an academic career is a bit like enjoying a box of chocolate – you never know what you are going to get next. In this talk, I will begin with sharing how luck, difficult decisions, fate, and family constraints affected my career path across continents, universities, the private sector, and to becoming a director at a national laboratory. This journey was certainly not planned and highlights how opportunities and compromises together allow you to make much more out of your engineering degree than you ever have dreamed of. After this unusual journey as a materials scientist, I am transitioning to the technical part of my talk, where we will discuss transport in metallic glasses. This out-of-equilibrium material has a long suite of remarkable mechanical and physical properties but suffers from property deterioration via physical aging. As a function of time, relaxation may indeed constitute significant threads to safe applications, such as a complete loss of toughness. In the search for a physical understanding of aging, we exploit here the ability to track atomic-scale dynamics with coherent x-ray scattering. Conducted across temperatures and under the application of stress, the results reveal unexpected transport. In concert with microsecond molecular dynamic simulations, we identify possible mechanisms of atomic-scale dynamics that underly physical aging of metallic glasses. We find that classical Kohlrausch-Williams-Watts behavior is only suited for the short relaxation-time regime, whereas anomalous diffusion emerges at practically relevant times. We discuss these results in terms of the structural relaxation modes and propose a picture of a true microstructure in metallic glasses. T2 - Department Seminar IIT Delhi 2023 CY - Delhi, India DA - 15.12.2023 KW - Metallic glass KW - Transport KW - Structure KW - Dynamics PY - 2023 AN - OPUS4-60649 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Riechers, Birte A1 - Ott, C. A1 - Das, S. M. A1 - Liebscher, C. A1 - Samwer, K. A1 - Derlet, P. M. A1 - Maaß, Robert T1 - On the elastic microstructure of bulk metallic glasses N2 - Metallic glasses (MGs) are known to be structurally heterogeneous at the nanometer (nm) scale. In addition, elastic property mapping has indicated the presence of at least an order-of-magnitude larger length scales, of which the origin continues to remain unknown. Here we demonstrate the existence of an elastic decorrelation length of the order of 100 nm in a Zr-based bulk MG using spatially resolved elastic property mapping via nanoindentation. Since compositional modulations sufficiently large to account for this elastic microstructure were not resolved by analytical scanning-transmission electron microscopy, chemical phase separation such as spinodal decomposition cannot explain their occurrence as previously suggested. Instead, we argue that the revealed long-range elastic modulations stem from structural variations affecting the local density. These emerge during solidification and are strongly influenced by the cooling constraints imposed on bulk MGs during the casting process. KW - Metallic glasses KW - Nanoindentation KW - Elastic microstructure PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573504 DO - https://doi.org/10.1016/j.matdes.2023.111929 SN - 0264-1275 VL - 229 SP - 1 EP - 8 PB - Elsevier Ltd. CY - Amsterdam, Niederlande AN - OPUS4-57350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darvishi Kamachali, Reza A1 - Wallis, Theophilus A1 - Ikeda, Yuki A1 - Saikia, U. A1 - Ahmadian, A. A1 - Liebscher, C. A1 - Hickel, Tilmann A1 - Maaß, Robert T1 - Giant segregation transition as origin of liquid metal embrittlement in the Fe-Zn system N2 - A giant Zn segregation transition is revealed using CALPHAD-integrated density-based modeling of segregation into Fe grain boundaries (GBs). The results show that above a threshold of only a few atomic percent Zn in the alloy, a substantial amount of up to 60 at.% Zn can segregate to the GB. We found that the amount of segregation abruptly increases with decreasing temperature, while the Zn content in the alloy required for triggering the segregation transition decreases. Direct evidence of the Zn segregation transition is obtained using high-resolution scanning transmission electron microscopy. Base on the model, we trace the origin of the segregation transition back to the low cohesive energy of Zn and a miscibility gap in Fe-Zn GB, arising from the magnetic ordering effect, which is confirmed by ab-initio calculations. We also show that the massive Zn segregation resulting from the segregation transition greatly assists with liquid wetting and reduces the work of separation along the GB. The current predictions suggest that control over Zn segregation, by both alloy design and optimizing the galvanization and welding processes, may offer preventive strategies against liquid metal embrittlement. KW - CALPHAD KW - Microstructure Design KW - Grain boundary engineering KW - Steels KW - Density-based Model KW - Segregation Engineering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584292 DO - https://doi.org/10.1016/j.scriptamat.2023.115758 SN - 1359-6462 SN - 1872-8456 VL - 238 SP - 1 EP - 5 PB - Elsevier CY - Amsterdam AN - OPUS4-58429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kar, Satyakam A1 - Ikeda, Yuki A1 - Nielsch, Kornelius A1 - Reith, Heiko A1 - Maaß, Robert A1 - Fähler, Sebastian T1 - Multiferroic Microstructure Created from Invariant Line Constraint N2 - Ferroic materials enable a multitude of emerging applications, and optimum functional properties are achieved when ferromagnetic and ferroelectric properties are coupled to a first‐order ferroelastic transition. In bulk materials, this first‐order transition involves an invariant habit plane, connecting coexisting phases: austenite and martensite. Theory predicts that this plane should converge to a line in thin films, but experimental evidence is missing. Here, the martensitic and magnetic microstructure of a freestanding epitaxial magnetic shape memory film is analyzed. It is shown that the martensite microstructure is determined by an invariant line constraint using lattice parameters of both phases as the only input. This line constraint explains most of the observable features, which differ fundamentally from bulk and constrained films. Furthermore, this finite‐size effect creates a remarkable checkerboard magnetic domain pattern through multiferroic coupling. The findings highlight the decisive role of finite‐size effects in multiferroics. KW - Epitaxial films KW - Finite-size effects KW - Multiferroics KW - Martensite KW - Magnetic shape memory alloys PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637910 DO - https://doi.org/10.1002/adfm.202416638 SN - 1616-301X VL - 35 IS - 10 SP - 1 EP - 11 PB - Wiley AN - OPUS4-63791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maaß, Robert A1 - Derlet, P. T1 - Micro-plasticity in a fragile model binary glass N2 - Atomistic deformation simulations in the nominally elastic regime are performed for a model binary glass with strain rates as low as 10 4 /s (corresponding to 0.01 shear strain per 1 μs). A strain rate dependent elastic softening due to a micro-plasticity is observed, which is mediated by thermally-activated localized structural transformations (LSEs). A closer inspection of the atomic-scale structure indicates the material response is distinctly different for two types of local atomic environments. A system spanning iscosahe- drally coordinated substructure responds purely elastically, whereas the remaining substructure admits both elastic and microplastic evolution. This leads to a heterogeneous internal stress distribution which, upon unloading, results in negative creep and complete residual-strain recovery. A detailed structural analysis in terms of local stress, atomic displacement, and SU(2) local bonding topology shows such mi- croscopic processes can result in large changes in local stress and are more likely to occur in geomet- rically frustrated regions characterized by higher free volume and softer elastic stiffness. The thermally- activated LSE activity also mediates structural relaxation, and in this way should be distinguished from stress-driven shear transformation activity which only rejuvenates glass structure. The frequency of LSE activity, and therefore the amount of micro-plasticity, is found to be related to the degree to which the glassy state is relaxed. These insights shed atomistic light onto the structural origins that may govern re- cent experimental observations of significant structural evolution in response to elastic loading protocols. KW - Molecular dynamics KW - Bulk metallic glasses KW - Plasticity KW - Residual strains PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523782 DO - https://doi.org/10.1016/j.actamat.2021.116771 VL - 209 SP - 116771 PB - Elsevier Ltd. AN - OPUS4-52378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ikeda, Yuki A1 - Yuan, R. A1 - Chakraborty, A. A1 - Ghassemi-Armaki, H. A1 - Zuo, J. M. A1 - Maaß, Robert T1 - Early stages of liquid-metal embrittlement in an advanced high-strength steel N2 - Grain-boundary degradation via liquid-metal embrittlement (LME) is a prominent and long-standing failure process in next generation advanced high-strength steels. Here we reveal, well ahead of the crack tip, the presences of nano-scale grains of intermetallic phases in Zn-infiltrated but uncracked grain boundaries with scanning- and 4D transmission electron microscopy. Instead of the often-reported Znrich Fe-Zn intermetallics, the nano-scale phase in the uncracked infiltrated grain boundaries is identified as the G-phase, and its presence reveals the local enhancement of strain heterogeneities in the grain boundary network. Based on these observations, we argue that intermetallic phase formation is not occurring after cracking and subsequent liquid Zn infiltration but is instead one of the primary nanoscopic drivers for grain-boundary weakening and crack initiation. These findings shift the focus of LME from micro- and meso-scale crack investigations to the very early stages immediately following Zn diffusion, after which secondary phase nucleation and growth emerge as the root-cause for failure. KW - Advanced high strength steels KW - Liquid metal embrittlement KW - Transmission electron microscopy KW - 4-Dimensional scanning transmission KW - electron microscopy PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539716 DO - https://doi.org/10.1016/j.mtadv.2021.100196 SN - 2590-0498 VL - 13 IS - 196 SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-53971 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maaß, Robert T1 - Beyond Serrated Flow in Bulk Metallic Glasses: What Comes Next? N2 - This manuscript is based on an oral contribution to the TMS 2020 annual meeting and is dedicated to Prof. Peter Liaw, who for decades has shown great interest in serrated plastic flow. Here we will focus on the case of bulk metallic glasses, and begin with briefly summarizing some aspects of serrated and non-serrated inhomogeneous flow—a phenomenon that has perplexed materials scientists for decades. Four directions of research are identified that emerged out of the desire to fundamentally understand the intermittent inhomogeneous flow response. These research directions gear away from the phenomenological stress–strain behavior but put the underlying shear defect into focus. Unsolved problems and future research topics are discussed. KW - Non-serrated inhomogeneous flow PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513106 DO - https://doi.org/10.1007/s11661-020-05985-w SN - 1073-5623 SP - 1 EP - 11 PB - Springer Nature AN - OPUS4-51310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zaiser, Erika A1 - Fareed, Adnan A1 - Manzoni, Anna Maria A1 - Paulisch-Rinke, Melanie C. A1 - Hsu, Wei-Che A1 - Yeh, An-Chou A1 - Murakami, Hideyuki A1 - Vogel, Florian A1 - Maaß, Robert T1 - Pinning-dominated strengthening in high-entropy superalloys N2 - Hierarchical microstructural design of high-entropy superalloys offers novel strengthening pathways beyond classical superalloys. Here we assess the strength of isolated γ’ precipitates with and without an additional internal γ nanophase. The results show that nano-precipitation within the γ’ phase leads to a marked statistical reduction of the dislocation-nucleation limited yield strength. In concert with disorder-driven chemical weakening of the γ’ phase, these findings indicate that bulk strengthening due to hierarchical microstructural design in high entropy superalloys must primarily be pinning dominated. KW - High-entropy alloys KW - Superalloys KW - Dislocation nucleation KW - Plasticity PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637590 DO - https://doi.org/10.1016/j.scriptamat.2025.116874 SN - 1359-6462 VL - 268 SP - 1 EP - 6 PB - Elsevier Inc. AN - OPUS4-63759 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ikeda, Yuki A1 - Han, Seungchang A1 - Wallis, Theophilus A1 - Darvishi Kamachali, Reza A1 - Maaß, Robert T1 - On the preference of liquid-metal embrittlement along high-angle grain-boundaries in galvanized steels N2 - Focusing on the early stages of liquid-metal embrittlement (LME) of Zinc (Zn) coated advanced high-strength steels, we show that the Zn infiltration path prior to grain-boundary decohesion and therefore cracking distinctly follows high-angle grain boundaries (HAGBs). This selective transport prior to LME-induced microcracking rationalizes the experimentally observed post-mortem cracking along martensitic HAGBs. We discuss the selective Zn transport and GB-weakening in terms of an misorientation-angle dependent atomic density and diffusivity, and its effect on GB-segregation. KW - Liquid-metal embrittlement KW - Advanced high-strength steels KW - Grain boundaries PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-631103 DO - https://doi.org/10.1016/j.scriptamat.2025.116723 SN - 1359-6462 VL - 265 SP - 1 EP - 5 PB - Elsevier Inc. AN - OPUS4-63110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sänger, Johanna Christiane A1 - Pauw, Brian Richard A1 - Riechers, Birte A1 - Zocca, Andrea A1 - Rosalie, Julian A1 - Maaß, Robert A1 - Sturm, Heinz A1 - Günster, Jens T1 - Entering a new dimension in powder processing for advanced ceramics shaping N2 - Filigree structures can be manufactured via two-photon-polymerization (2PP) operating in the regime of non-linear light absorption. For the first time it is possible to apply this technique to the powder processing of ceramic structures with a feature size in the range of the critical defect size responsible for brittle fracture and, thus, affecting fracture toughness of high-performance ceramics. In this way, tailoring of advanced properties can be achieved already in the shaping process. Traditionally, 2PP relies on transparent polymerizable resins, which is diametrically opposed to the usually completely opaque ceramic resins and slurries. Here we present a transparent and photocurable suspension of nanoparticles (resin) with very high mass fractions of yttria-stabilized zirconia particles (YSZ). Due to the extremely well dispersed nanoparticles, scattering of light can be effectively suppressed at the process-relevant wavelength of 800 nm. Sintered ceramic structures with a resolution of down to 500 nm were obtained. Even at reduced densities of 1 to 4 g/cm³, the resulting compressive strength with 4,5 GPa is equivalent or even exceeding bulk monolithic yttria stabilized zirconia. A ceramic metamaterial is born, where the mechanical properties of yttria stabilized zirconia are altered by changing geometrical parameters and gives access to a new class of ceramic materials. KW - Two-photon-polymerization KW - Ceramics KW - Powder processing KW - Transparency KW - Meta material KW - Yttria stabilized zirconia PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564598 DO - https://doi.org/10.1002/adma.202208653 SN - 1521-4095 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim AN - OPUS4-56459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dudziak, Mateusz A1 - Riechers, Birte A1 - Maaß, Robert A1 - Michalchuk, Adam A1 - Schönhals, Andreas A1 - Szymoniak, Paulina T1 - Beyond conventional calorimetry: Unlocking thermal characterization with fast scanning techniques N2 - Fast scanning calorimetry (FSC) has emerged as a transformative technique in thermal analysis, enabling the investigation of rapid and kinetically driven thermal transitions that are inaccessible to conventional differential scanning calorimetry. This review highlights the capabilities enabled by FSC for studying a wide range of materials under extreme thermal conditions, including polymers, pharmaceuticals, metallic glasses, nanocomposites, and hydrogels. By employing ultrafast heating and cooling rates, FSC allows for the suppression of crystallization, resolution of weak transitions, and analysis of thermally labile or size-limited samples. The technique is particularly valuable for probing glass transitions, relaxation phenomena, and phase behavior in systems with complex morphologies or confined geometries. Case studies demonstrate the use of FSC in characterizing vitrification, physical aging, and interfacial dynamics, as well as its application in emerging fields such as additive manufacturing, supramolecular systems, and neuromorphic materials. Together, these examples underscore the role that FSC plays in advancing the understanding of structure-property relationships across diverse material classes. KW - Flash DSC KW - Calorimetry KW - Glass transition PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-647405 DO - https://doi.org/10.1016/j.tca.2025.180177 VL - 754 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-64740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hickel, Tilmann A1 - Waske, Anja A1 - Tehranchi, Ali A1 - Bhattacharya, Biswajit A1 - Stawski, Tomasz M. A1 - Fellinger, Tim-Patrick A1 - Mehmood, Asad A1 - Witt, Julia A1 - Ozcan, Ozlem A1 - Guilherme Buzanich, Ana A1 - Kumar, Sourabh A1 - Mishra, Rajesh Kumar A1 - Holzer, Marco A1 - Stucchi de Camargo, Andrea Simone A1 - Agudo Jácome, Leonardo A1 - Manzoni, Anna A1 - Fantin, Andrea A1 - John, Elisabeth A1 - Hodoroaba, Vasile-Dan A1 - Bührig, Sophia A1 - Murugan, Jegatheesan A1 - Marschall, Niklas A1 - George, Janine A1 - Darvishi Kamachali, Reza A1 - Maaß, Robert A1 - Emmerling, Franziska T1 - Chemically complex materials enable sustainable high-performance materials N2 - Chemically complex materials (CCMats) 􀀀 including high-entropy alloys, oxides, and related multi-principal element systems 􀀀 offer a paradigm shift in materials design by leveraging chemical diversity to simultaneously optimize functional, structural, and sustainability criteria. The vastness of the compositional and structural space in CCMats propels the field into an expanding exploratory state. To reconcile functional and structural performance across this immense parameter space remains an open challenge. This Perspective evaluates the opportunities and challenges associated with harnessing chemical complexity across a broad spectrum of applications, such as hydrogen storage, ionic conductors, catalysis, magnetics, dielectrics, semiconductors, optical materials, and multifunctional structural systems. It is delineated how three central design strategies: targeted substitution (SUB), defect engineering (DEF), and diversity management (DIV) enable the reconciliation of high functional performance with long-term structural stability and environmental responsibility. Advances in computational thermodynamics, microstructure simulations, machine learning, and multimodal characterization are accelerating the exploration and optimization of CCMats, while robust data infrastructures and automated synthesis workflows are emerging as essential tools for navigating their complex compositional space. By fostering cross-disciplinary knowledge transfer and embracing data-driven design, CCMats are poised to deliver next-generation materials solutions that address urgent technological, energy, and environmental demands. KW - Chemically complex materials KW - Structural stability KW - Functional performance KW - Design strategies KW - Sustainability PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655598 UR - https://www.sciencedirect.com/science/article/pii/S1359028626000033?via%3Dihub DO - https://doi.org/10.1016/j.cossms.2026.101256 SN - 1359-0286 VL - 42 SP - 1 EP - 26 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-65559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Riechers, Birte A1 - Pekin, Thomas C. A1 - Luo, Xin-Yu A1 - Sun, Yonghao A1 - Koch, Christoph T. A1 - Derlet, Peter M. A1 - Maaß, Robert T1 - Spatial distribution and connectivity of medium-range order signatures in a metallic glass probed with simulated and experimental 4DSTEM N2 - challenge. Here, we assess the statistical signature of local diffraction symmetries and their spatial distribution obtained with transmission electron microscopy in both experimentally cast Pd-based MGs and simulated binary model glasses. A detailed analysis of diffraction symmetries from the model glass shows that microstructural coarsening is dominated by icosahedra and Frank–Kasper polyhedra. While symmetries for these motifs are less significant for the laboratory-cast Pd-based glass, clear signatures of symmetry-cluster coarsening as a function of relaxation state are observed in both experiments and simulations, without any indications for crystallization. These findings give support for a qualitatively similar evolution of a glassy microstructure at the medium-range order length scale during glass relaxation. KW - Metallic glass KW - TEM KW - Molecular dynamics simulations KW - Glass structure PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-657772 DO - https://doi.org/10.1016/j.jallcom.2026.186631 SN - 0925-8388 VL - 1058 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-65777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -