TY - JOUR A1 - Al-Falahat, A. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Kupsch, Andreas A1 - Woracek, R. A1 - Alrwashdeh, S. A1 - Manke, I. T1 - Investigation of detector backlighting and other effects in neutron darkfield images N2 - Neutron imaging can provide unique contrast mechanisms. In order to yield reliable and reproducible attenuation coefficients for quantification, one needs to fully understand and characterize the experimental set-up. One effect that has been largely overlooked in scintillator-camera based neutron imaging systems is the backlight scattering or back illumination in the detection system which can significantly affect the quantification of attenuation coefficients and lead to severe errors and image artifacts. Herein, backlighting is investigated by varying the illuminated detector area and the magnitude of the attenuation. The attenuation coefficient of multiple metal plates was determined by polychromatic neutrons bu the CONRAD V7 instrument. The strength of the back illumination strongly depends upon the sample absorption. While it is relatively moderate (a few percent) for weak absorbing samples, it can be severe when the sample is a strong absorber or thick. KW - Attenuation coefficient KW - Neutron imaging KW - Neutron scattering KW - Polycromatic neutrons KW - Scintillator PY - 2024 SN - 1073-9149 DO - https://doi.org/10.1080/10739149.2024.2380772 SP - 1 EP - 11 PB - Taylor & Francis AN - OPUS4-60752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Trogadas, P. A1 - Cho, J. I. S. A1 - Rasha, L. A1 - Lu, X. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Manke, I. A1 - Shearing, P. R. A1 - Brett, D. J. L. A1 - Coppens, M. O. T1 - A nature-inspired solution for water management in flow fields for electrochemical devices N2 - A systematic, nature-inspired chemical engineering approach is employed to solve the issue of flooding in electrochemical devices. The mechanism of passive water transport utilized by lizards living in arid environments is leveraged to design flow-fields with a microchannel structure on their surface, through which capillary pressure rapidly removes the water generated in the electrochemical device. This water management strategy is implemented in proton exchange membrane fuel cells (PEMFCs) with a lunginspired flow-field, which ensures uniform distribution of reactants across the catalyst layer. Jointly, this nature-inspired approach results in flood-free, stable operation at 100% RH and a B60% increase in current (B1.9 A cm-2) and peak power density (B650 mW cm−2) compared to current PEMFCs with a flood-prone, serpentine flow-field (B0.8 A cm-2 and 280 mW cm-2, respectively). This significant advance allows for PEMFC operation at fully humidified conditions. KW - Neutron imaging KW - X-ray tomography KW - Fuel cell PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596662 DO - https://doi.org/10.1039/d3ee03666a VL - 17 SP - 2007 EP - 2017 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano Munoz, Itziar A1 - Pfretzschner, Beate A1 - Kromm, Arne A1 - Nadammal, Naresh A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Neuwirth, T. A1 - Schulz, M. A1 - Griesche, Axel T1 - High-resolution Bragg-edge neutron radiography detects grain morphology in PBF-LB/M IN718 N2 - One of the main advantages of metal additive manufacturing (MAM) techniques is their ability to produce components with site-specific microstructural features. Nevertheless, microstructural defects and lack of repeatability are still major concerns in MAM. In this study, a laser powder bed fusion (PBF-LB/M) IN718 material, produced using two different scan length vectors, is investigated using Bragg-edge neutron 2D imaging (BENI) combined with electron backscatter diffraction (EBSD) analysis. BENI is able to detect, on a macroscopic scale, process-induced changes in texture in a large field of view covering the entire sample (20×80 mm2). In addition, high-resolution BENI (HR-BENI), with a pixel size of 12.8 µm, provides a micro-scale examination of the local variations of texture and grain morphology, otherwise undistinguishable using the standard resolution. As such, HR-BENI offers a straightforward and detailed way of screening the integrity of MAM parts at cm-length scales. KW - Bragg-edge neutron 2D imaging (BENI) KW - Metal additive manufacturing (MAM) KW - IN718 PBF-LB/M KW - Crystallographic texture control KW - Electron backscatter diffraction (EBSD) PY - 2023 DO - https://doi.org/10.1016/j.mtla.2023.101827 SN - 2589-1529 VL - 30 SP - 1 EP - 6 PB - Elsevier CY - Amsterdam AN - OPUS4-57819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jamro, R. A1 - Mente, Tobias A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Al-Falahat, Ala'A. M. A1 - Woracek, R. A1 - Manke, I. A1 - Griesche, Axel T1 - Temperature distribution during welding measured by neutron imaging N2 - This study was carried out to investigate the neutron transmission signal as a function of sample temperature during a welding process. A theoretical description that includes the Debye-Waller factor was used to describe the temperature influence on the neutron crosssections. Neutron imaging using a monochromatic beam helps to observe transmission variations related to the material temperature. In-situ neutron imaging of welding experiments show the distribution of the temperature in bulk steel samples. The performed finite element modelling of expected temperature distributions shows good agreement with the obtained experimental data. KW - Neutron imaging KW - Debye-Waller-Faktor PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586268 DO - https://doi.org/10.1088/1742-6596/2605/1/012026 VL - 2605 SP - 1 EP - 10 PB - IOP Publishing Ltd. AN - OPUS4-58626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Mente, Tobias A1 - Markötter, Henning A1 - Al-Falahat, M. A1 - Kardjilov, N. T1 - Neutron Bragg edge imaging for in situ mapping of crystallographic phase-transformations and of temperature distributions during GTAW of supermartensitic stainless steel N2 - In Neutron-Bragg-Edge Imaging (NBEI) experiments, we studied the phase transition during butt-welding of supermartensitic steel plates. Gas tungsten arc welding (GTAW) was used with a motorized torch allowing for automated weldments. The austenitization in the heat affected zone (HAZ) underneath the welding head could be clearly visualized at λ = 0.39 nm, a wavelength smaller than the Bragg edge wavelengths of both austenite and martensite. Also, the re-transformation into the martensitic phase upon cooling was detected. However, we observed an unexpected additional change in transmission at λ = 0.44 nm that is a wavelength larger than the wavelength of the Bragg edges of both the martensitic and austenitic phases. We attribute this change to the Deybe-Waller-Factor that describes the temperature dependence of coherent scattering at a crystal lattice. The observed two-dimensional attenuation map corresponds well with a temperature distribution modelling by software macros in ANSYS. Here, the absolute temperature values could be achieved by calibrating the modelled attenuation with help of a thermocouple placed at the steel plate. This allows in return for a direct two-dimensional temperature reading based on the Debye-Waller-relation between neutron attenuation and sample temperature. T2 - ITMNR-9 CY - Buenos Aires, Argentina DA - 12.10.2022 KW - Debye-Waller-Faktor PY - 2023 AN - OPUS4-58627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ziesche, R.F. A1 - Hack, J. A1 - Rasha, L. A1 - Maier, M. A1 - Tan, C. A1 - Heenan, T.M.M. A1 - Markötter, Henning A1 - Kardjilov, N. A1 - Manke, I. A1 - Kockelmann, W. A1 - Brett, D.J.L. A1 - Shearing, P.R. T1 - High-speed 4D neutron computed tomography for quantifying water dynamics in polymer electrolyte fuel cells N2 - In recent years, low-temperature polymer electrolyte fuel cells have become an increasingly important pillar in a zero-carbon strategy for curbing climate change, with their potential to power multiscale stationary and mobile applications. The performance improvement is a particular focus of research and engineering roadmaps, with water management being one of the major areas of interest for development. Appropriate characterisation tools for mapping the evolution, motion and removal of water are of high importance to tackle shortcomings. This article demonstrates the development of a 4D high-speed neutron imaging technique, which enables a quantitative analysis of the local water evolution. 4D visualisation allows the time-resolved studies of droplet formation in the flow fields and water quantification in various cell parts. Performance parameters for water management are identified that offer a method of cell classification, which will, in turn, support computer modelling and the engineering of next-generation flow field designs. KW - Neutron imaging KW - Tomography KW - Polymer electrolyte membrane fuel cell PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-545978 DO - https://doi.org/10.1038/s41467-022-29313-5 VL - 13 IS - 1 SP - 1616 PB - Nature Publishing Group UK CY - London AN - OPUS4-54597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tengattini, A A1 - Kardjilov, N A1 - Helfen, L A1 - Douissard, P A A1 - Lenoir, N A1 - Markötter, Henning A1 - Hilger, A A1 - Arlt, T A1 - Paulisch, M A1 - Turek, T A1 - Manke, Ingo T1 - Compact and versatile neutron imaging detector with sub-4μm spatial resolution based on a single-crystal thin-film scintillator N2 - A large and increasing number of scientific domains pushes for high neutron imaging resolution achieved in reasonable times. Here we present the principle, design and performance of a detector based on infinity corrected optics combined with a crystalline Gd3Ga5O12 : Eu scintillator, which provides an isotropic sub-4 μm true resolution. The exposure times are only of a few minutes per image. This is made possible also by the uniquely intense cold neutron flux available at the imaging beamline NeXT-Grenoble. These comparatively rapid acquisitions are compatible with multiple high quality tomographic acquisitions, opening new venues for in-operando testing, as briefly exemplified here. KW - Neutron imaging KW - Scintillator KW - Resolution PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549836 DO - https://doi.org/10.1364/oe.448932 VL - 30 IS - 9 SP - 14461 EP - 14477 PB - Optica CY - Washington, DC AN - OPUS4-54983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kardjilov, N. T1 - Quantification of hydrogen in metals applying neutron imaging techniques N2 - Hydrogen interaction with metals is well known to have severe detrimental effects on their mechanical properties. The use of modern high-strength steels, which are attractive to improve fuel economy by reducing weight as well as candidates for H storage cylinders and other components, is currently being severely limited by the fact that the presence of H can cause embrittlement of the material. In addition to steel, several other metals and alloys used in the nuclear industry, like Ti and Zr, are susceptible to H degradation through hydride formation and subsequent cracking. Microstructure-specific H mapping has been recognized as the most important challenge on the pathway towards a better understanding of the nature of H embrittlement in metallic alloys as well as the development of H storage solutions based on metal hydrides. Unfortunately, the characterization of H interactions with metals is an extremely challenging task and neutron-based techniques are of exceptional importance in this matter because – contrary to X-rays and electrons – thermal and cold neutrons interact strongly with the H nuclei, while the neutron beam is only weakly attenuated by the relevant metallic materials. Therefore, hydrogen distributions can be measured and quantified even in 3D by tomographic methods. Here we present several neutron imaging investigations of embrittlement and cracking in Fe and Zr based metal alloys and optimization studies of hydrogen storage systems containing metal hydrides as an active substance. The advantages and the limitations of the experimental methods as well as the attempts for hydrogen quantification will be discussed in detail. T2 - M&M 2022 Annual Meeting (Microscopy & Microanalysis) CY - Portland, Oregon, USA DA - 31.07.2022 KW - Neutron imaging techniques KW - Hydrogen in metals PY - 2022 DO - https://doi.org/10.1017/S1431927622006638 AN - OPUS4-55716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Al-Falahat, A M A1 - Kardjilov, N A1 - Woracek, R A1 - Boin, M A1 - Markötter, Henning A1 - Kuhn, L T A1 - Makowska, M A1 - Strobl, M A1 - Pfretzschner, B A1 - Banhart, J A1 - Manke, I T1 - Temperature dependence in Bragg edge neutron transmission measurements N2 - A systematic study has been carried out to investigate the neutron transmission signal as a function of sample temperature. In particular, the experimentally determined wavelength-dependent neutron attenuation spectra for a martensitic steel at temperatures ranging from 21 to 700°C are compared with simulated data. A theoretical description that includes the Debye–Waller factor in order to describe the temperature influence on the neutron cross sections was implemented in the nxsPlotter software and used for the simulations. The analysis of the attenuation coefficients at varying temperatures shows that the missing contributions due to elastic and inelastic scattering can be clearly distinguished: while the elastically scattered intensities decrease with higher temperatures, the inelastically scattered intensities increase, and the two can be separated from each other by analysing unique sharp features in the form of Bragg edges. This study presents the first systematic approach to quantify this effect and can serve as a basis , for example, to correct measurements taken during in situ heat treatments, in many cases being a prerequisite for obtaining quantifiable results. KW - Neutron Bragg edge imaging KW - Debye–Waller factor KW - Temperature-dependent neutron transmission KW - Super martensitic stainless steel PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556896 DO - https://doi.org/10.1107/S1600576722006549 VL - 55 IS - Pt 4 SP - 919 EP - 928 PB - International Union of Crystallography AN - OPUS4-55689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silveira, A. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Longo, E. A1 - Greving, I. A1 - Lasch, P. A1 - Shahar, R A1 - Zaslansky, P. T1 - Water flow through bone: Neutron tomography reveals differences in water permeability between osteocytic and anosteocytic bone material N2 - Vertebrate bones are made of a nanocomposite consisting of water, mineral and organics. Water helps bone material withstand mechanical stress and participates in sensation of external loads. Water diffusion across vertebrae of medaka (bone material lacking osteocytes) and zebrafish (bone material containing osteocytes) was compared using neutron tomography. Samples were measured both wet and following immersion in deuterated-water (D2O). By quantifying H+ exchange and mutual alignment with X-ray lCT scans, the amount of water expelled from complete vertebra was determined. The findings revealed that anosteocytic bone material is almost twice as amenable to D2O diffusion and H2O exchange, and that unexpectedly, far more water is retained in osteocytic zebrafish bone. Diffusion in osteocytic bones (only 33 % – 39 % water expelled) is therefore restricted as compared to anosteocytic bone (~ 60 % of water expelled), presumably because water flow is confined to the lacunar-canalicular network (LCN) open-pore system. Histology and Raman spectroscopy showed that anosteocytic bone contains less proteoglycans than osteocytic bone. These findings identify a previously unknown functional difference between the two bone materials. Therefore, this study proposes that osteocytic bone retains water, aided by non-collagenous proteins, which contribute to its poroelastic mechano-transduction of water flow confined inside the LCN porosity. KW - Bone porosity KW - Anosteocytic bone KW - Water permeability KW - Neutron tomography KW - Proteoglycans PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564563 DO - https://doi.org/10.1016/j.matdes.2022.111275 VL - 224 SP - 1 EP - 13 PB - Elsevier Ltd. AN - OPUS4-56456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -