TY - CONF A1 - Bruno, Giovanni A1 - Mishurova, Tatiana A1 - Evlevleev, Sergei A1 - Khrapov, D. A1 - Meinel, Dietmar A1 - Surmenev, R. A1 - Surmeneva, M. A1 - Koptyug, A. T1 - Procedures to Quantitatively Characterize Morphological Features of Triply Periodic Minimal Surface Structures N2 - Additively manufactured (AM) metallic sheet-based Triply Periodic Minimal Surface Structures (TPMSS) meet several requirements in both bio-medical and engineering fields: Tunable mechanical properties, low sensitivity to manufacturing defects, mechanical stability, and high energy absorption. However, they also present some challenges related to quality control. In fact, the optimization of both the AM process and the properties of TPMSS is impossible without considering structural characteristics as manufacturing accuracy, internal defects, and as well as surface topography and roughness. In this study, the quantitative non-destructive analysis of TPMSS manufactured from Ti-6Al-4V alloy by electron beam melting was performed by means of laboratory X-ray computed tomography (XCT). T2 - International conference on tomography of material and structures 2022 CY - Grenoble, France DA - 27.06.2022 KW - Additive manufacturing KW - Scaffold KW - Lightweight structures KW - Computed tomography PY - 2022 AN - OPUS4-55229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Evsevleev, Sergei A1 - Mishurova, Tatiana A1 - Meinel, Dietmar A1 - Koptyug, A. A1 - Surmeneva, M. A1 - Khrapov, D. A1 - Paveleva, A. A1 - Surmenev, R. T1 - Procedures for quantitative characterization of periodic minimal surface structures (TMPSS) N2 - Additively manufactured (AM) triply periodic metallic minimum surface structures (TPMSS, from the English Triply Periodic Minimum Surface Structures) fulfill several requirements in both biomedical and engineering fields: tunable mechanical properties, low sensitivity to manufacturing defects, mechanical stability, and high energy absorption. However, they also present some quality control challenges that may prevent their successful application. In fact, optimization of the AM process is impossible without considering structural features such as manufacturing accuracy, internal defects, and surface topography and roughness. In this study, quantitative nondestructive analysis of Ti-6Al-4V alloy TPMSS was performed using X-ray computed tomography (XCT). Several new image analysis workflows are presented to evaluate the effects of buildup direction on wall thickness distribution, wall degradation, and surface roughness reduction due to chemical etching of TPMSS. It is shown that the fabrication accuracy is different for the structural elements printed parallel and orthogonal to the fabricated layers. Different strategies for chemical etching showed different powder removal capabilities and thus a gradient in wall thickness. This affected the mechanical performance under compression by reducing the yield stress. A positive effect of chemical etching is the reduction of surface roughness, which can potentially improve the fatigue properties of the components. Finally, XCT was used to correlate the amount of powder retained with the pore size of the TPMSS, which can further improve the manufacturing process. T2 - MSE 2022 CY - Darmstadt, Germany DA - 27.09.2022 KW - Surface roughness KW - Additive manufacturing KW - Computed tomography KW - Wall thickness KW - Machine learning KW - Manufacturing defects PY - 2022 AN - OPUS4-56162 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Laquai, René A1 - Schaupp, Thomas A1 - Griesche, Axel A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Hannemann, Andreas A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - Quantitative analysis of hydrogen-assisted microcracking in duplex stainless steel through X-ray refraction 3D imaging JF - Advanced engineering materials N2 - While the problem of the identification of mechanisms of hydrogen assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field-of-views and high spatial resolution. Synchrotron X-ray refraction techniques do possess both features. In this work, we show how synchrotron X-ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X-ray absorption computed tomography. As already reported in literature, but this time using a non-destructive technique, we show that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen-charged specimens, we deduce that cracks in the specimen bulk are due to the rolling process rather than hydrogen-assisted. We show that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and we deduce that a significant crack propagation can only be observed short before rupture. KW - 2101 duplex stainless steel KW - Hydrogen embrittlement KW - Synchrotron radiation KW - X-ray refraction KW - Computed tomography KW - Microcracking PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542811 DO - https://doi.org/10.1002/adem.202101287 SN - 1438-1656 SP - 1 EP - 10 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54281 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritsch, Tobias A1 - Farahbod-Sternahl, L. A1 - Serrano Munoz, Itziar A1 - Léonard, F. A1 - Haberland, C. A1 - Bruno, Giovanni T1 - 3D Computed Tomography Quantifies the Dependence of Bulk Porosity, Surface Roughness, and Re-Entrant Features on Build Angle in Additively Manufactured IN625 Lattice Struts JF - Advanced Engineering Materials N2 - Layer-by-layer additive manufacturing (AM) by means of laser-powder bed Fusion (L-PBF) offers many prospects regarding the design of lattice structures used, for example, in gas turbines. However, defects such as bulk porosity, Surface roughness, and re-entrant features are exacerbated in nonvertical structures, such as tilted struts. The characterization and quantification of these kinds of defects are essential for the correct estimation of fracture and fatigue properties. Herein, cylindrical struts fabricated by L-PBF are investigated by means of X-ray computed tomography (XCT), with the aim of casting light on the dependence of the three kinds of defects (bulk porosity, surface roughness, and re-entrant features) on the build angle. Innovative analysis methods are proposed to correlate shape and position of pores, to determine the angular-resolved Surface roughness, and to quantify the amount of re-entrant surface features, q. A meshing of the XCT surface enables the correlation of q with the classical Surface roughness Pa. This analysis leads to the conclusion that there is a linear correlation between q and Pa. However, it is conjectured that there must be a threshold of surface roughness, below which no re-entrant features can be build. KW - Additive manufacturing KW - Laser powder bed fusion KW - Computed tomography KW - Surface roughness analysis KW - Re-entrant surface feature PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534728 DO - https://doi.org/10.1002/adem.202100689 IS - 2100689 SP - 1 EP - 8 PB - Wiley-VCH Verlag AN - OPUS4-53472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Magkos, Sotirios A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Suppression of Cone-Beam Artefacts with Direct Iterative Reconstruction Computed Tomography Trajectories (DIRECTT) JF - Journal of Imaging N2 - The reconstruction of cone-beam computed tomography data using filtered back-projection algorithms unavoidably results in severe artefacts. We describe how the Direct Iterative Reconstruction of Computed Tomography Trajectories (DIRECTT) algorithm can be combined with a model of the artefacts for the reconstruction of such data. The implementation of DIRECTT results in reconstructed volumes of superior quality compared to the conventional algorithms. KW - DIRECTT KW - Iterative method KW - Signal processing KW - X-ray imaging KW - Computed tomography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531085 DO - https://doi.org/10.3390/jimaging7080147 SN - 2313-433X) VL - 7 IS - 8 SP - 147 - 1 EP - 147 -9 PB - MDPI CY - Basel, Switzerland AN - OPUS4-53108 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D. A1 - Kozadayeva, M. A1 - Manabaev, K. A1 - Panin, A. A1 - Sjöström, W. A1 - Koptyug, A. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Meinel, Dietmar A1 - Bruno, Giovanni A1 - Cheneler, D. A1 - Surmenev, R. A1 - Surmeneva, M. T1 - Different approaches for manufacturing Ti-6Al-4V alloy with triply periodic minimal surface sheet-based structures by electron beam melting JF - Materials N2 - Targeting biomedical applications, Triply Periodic Minimal Surface (TPMS) gyroid sheet-based structures were successfully manufactured for the first time by Electron Beam Melting in two different production Themes, i.e., inputting a zero (Wafer Theme) and a 200 µm (Melt Theme) wall thickness. Initial assumption was that in both cases, EBM manufacturing should yield the structures with similar mechanical properties as in a Wafer-mode, as wall thickness is determined by the minimal beam spot size of ca 200 µm. Their surface morphology, geometry, and mechanical properties were investigated by means of electron microscopy (SEM), X-ray Computed Tomography (XCT), and uniaxial tests (both compression and tension). Application of different manufacturing Themes resulted in specimens with different wall thicknesses while quasi-elastic gradients for different Themes was found to be of 1.5 GPa, similar to the elastic modulus of human cortical bone tissue. The specific energy absorption at 50% strain was also similar for the two types of structures. Finite element simulations were also conducted to qualitatively analyze the deformation process and the stress distribution under mechanical load. Simulations demonstrated that in the elastic regime wall, regions oriented parallel to the load are primarily affected by deformation. We could conclude that gyroids manufactured in Wafer and Melt Themes are equally effective in mimicking mechanical properties of the bones. KW - Electron beam melting KW - Scaffold KW - Lightweight structures KW - Computed tomography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531595 DO - https://doi.org/10.3390/ma14174912 SN - 1996-1944 VL - 14 IS - 17 SP - 1 EP - 21 PB - MDPI CY - Basel AN - OPUS4-53159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markötter, Henning A1 - Sintschuk, Michael A1 - Britzke, Ralf A1 - Dayani, Shahabeddin A1 - Bruno, Giovanni T1 - Upgraded imaging capabilities at the BAMline (BESSY II) JF - Journal of Synchrotron Radiation N2 - The BAMline at the BESSY II synchrotron X-ray source has enabled research for more than 20 years in widely spread research fields such as materials science, biology, cultural heritage and medicine. As a nondestructive characterization method, synchrotron X-ray imaging, especially tomography, plays a particularly important role in structural characterization. A recent upgrade of key equipment of the BAMline widens its imaging capabilities: shorter scan acquisition times are now possible, in situ and operando studies can now be routinely performed, and different energy spectra can easily be set up. In fact, the upgraded double-multilayer monochromator brings full flexibility by yielding different energy spectra to optimize flux and energy resolution as desired. The upgraded detector (based on an sCMOS camera) also allows exploiting the higher flux with reduced readout times. Furthermore, an installed slip ring allows the sample stage to continuously rotate. The latter feature enables tomographic observation of processes occurring in the time scale of a few seconds. KW - Synchrotron radiation KW - Computed tomography KW - Double-multilayer monochromators KW - Pink beams KW - X-ray optics PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556907 DO - https://doi.org/10.1107/S1600577522007342 SN - 1600-5775 VL - 29 IS - Pt 5 SP - 1292 EP - 1298 PB - International Union of Crystallography CY - Chester AN - OPUS4-55690 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Evsevleev, Sergei A1 - Sevostianov, I. A1 - Mishurova, Tatiana A1 - Cabeza, S. A1 - Koos, R. A1 - Hofmann, M. A1 - Requena, G. A1 - Garcés, G. T1 - Explaining deviatoric residual stresses and load transfer in aluminum alloys and composites with complex microstructure N2 - The residual stresses and load transfer in multiphase metal alloys and their composites (with both random planar-oriented short fibers and particles) will be shown, as studied by neutron diffraction, by X-ray computed tomography, and by a model based on the reformulation of classic Maxwell’s homogenization method. Contrary to common understanding and state-of-the-art models, we experimentally observe that randomly oriented phases possess non-hydrostatic residual stress. Moreover, we disclose that the unreinforced matrix alloy stays under hydrostatic compression even under external uniaxial compression. The recently developed modeling approach allows calculating the residual stress in all phases of the composites. It rationalizes the presence of deviatoric stresses accounting for the interaction of random oriented phases with fibers having preferential orientation. It also allows the explanation of the unconventional in-situ behavior of the unreinforced alloy and the prediction of the micromechanical behavior of other similar alloys. T2 - MLZ Conference 2022: Neutrons for Mobility CY - Lenggries, Germany DA - 31.05.2022 KW - Load transfer KW - Neutron Diffraction KW - micromechanical modeling KW - Computed tomography PY - 2022 AN - OPUS4-55405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Khrapov, D. A1 - Paveleva, A. A1 - Meinel, Dietmar A1 - Surmenev, R. A1 - Surmenev, M. A1 - Koptyug, A. T1 - Procedures to Quantitatively Characterize Morphological Features of Triply Periodic Minimal Surface Structures (TPMSS) N2 - The residual stresses and load transfer in multiphase metal alloys and their composites (with both random planar-oriented short fibers and particles) will be shown, as studied by neutron diffraction, by X-ray computed tomography, and by a model based on the reformulation of classic Maxwell’s homogenization method. Contrary to common understanding and state-of-the-art models, we experimentally observe that randomly oriented phases possess non-hydrostatic residual stress. Moreover, we disclose that the unreinforced matrix alloy stays under hydrostatic compression even under external uniaxial compression. The recently developed modeling approach allows calculating the residual stress in all phases of the composites. It rationalizes the presence of deviatoric stresses accounting for the interaction of random oriented phases with fibers having preferential orientation. It also allows the explanation of the unconventional in-situ behavior of the unreinforced alloy and the prediction of the micromechanical behavior of other similar alloys. T2 - 5th International Conference on Tomography of Materials and Structures CY - Grenoble, France DA - 27.06.2022 KW - Load transfer KW - Neutron Diffraction KW - Micromechanical modeling KW - Computed tomography PY - 2022 AN - OPUS4-55406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Onel, Yener A1 - Lange, Axel A1 - Staude, Andreas A1 - Ehrig, Karsten A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Wolk, Thomas A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Evaluating porosity in cordierite Diesel particulate filter materials, Part 2 statistical analysis of computed tomography data JF - Journal of ceramic science and technology N2 - Complementary to Part 1 of this work, the bi-continuous microstructure of porous synthetic cordierite ceramics for filtration applications was investigated using 3D x-ray computed tomography at different resolutions. Applying both Fast Fourier Transform and a newly developed image analysis algorithm, we quantitatively evaluated porosity and pore orientation. The statistical approach allows extraction of spatially resolved or average values. Porosity values based on x-ray absorption agree with mercury intrusion measurements, while pore orientation factors agree with x-ray refraction data (Part 1 of this work), and with published crystallographic texture data. KW - Pore orientation KW - Porous ceramics KW - Computed tomography KW - 3D microstructure PY - 2013 DO - https://doi.org/10.4416/JCST2013-00022 SN - 2190-9385 VL - 05 IS - 01 SP - 13 EP - 22 PB - Göller CY - Baden-Baden AN - OPUS4-30379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Laquai, René A1 - Schaupp, Thomas A1 - Müller, Bernd R. A1 - Griesche, Axel A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - 3D Crack analysis in hydrogen charged lean duplex stainless steel with synchrotron refraction CT T2 - Proceeedings of the 19th World Conference on Non-Destructive Testing 2016 N2 - Hydrogen in metals can cause a degradation of the mechanical properties, the so-called hydrogen embrittlement. In combination with internal stresses, hydrogen assisted cracking (HAC) can occur. This phenomenon is not completely understood yet. To better characterise the cracking behaviour, it is important to gain information about the evolution of the 3D crack network. For this purpose samples of lean duplex stainless steel were loaded with hydrogen by means of electrochemical charging and investigated by means of synchrotron refraction CT and SEM fractography after uniaxial tensile loading. Synchrotron refraction CT is an analyser-based imaging (ABI) technique. It uses a Si (111) single crystal as analyser, which is placed into the beam path between sample and detector. According to Bragg’s law only incident x-rays within a narrow range around the Bragg-angle are diffracted from the analyser into the detector. Hence, the analyser acts as an angular filter for the transmitted beam. This filtering allows to turn the refraction and scattering of x-rays into image contrast. Refraction occurs at all interfaces, where the density of the material changes and is more sensitive to density changes than the attenuation. Therefore, it is possible to detect smaller cracks than with classical x-ray imaging techniques, like CT, with comparable spacial resolution. It also visualises the 3D structure of the cracks and gains quantitative information about their morphology and distribution. Since cracks introduced by HAC are usually very small and have a small opening displacement, synchrotron refraction CT is expected to be well suited for imaging this cracking mechanism and can be a valuable tool to characterise the formation and the evolution of a 3D crack network. T2 - WCNDT 2016 CY - München, Germany DA - 13.06.2016 KW - X-ray refraction KW - Computed tomography KW - Hydrogen assisted cracking KW - Duplex stainless steel PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366481 SN - 978-3-940283-78-8 VL - BB 158 SP - Tu.4.B.3, 1 EP - 9 AN - OPUS4-36648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rifai, Haifa A1 - Staude, Andreas A1 - Meinel, Dietmar A1 - Illerhaus, Bernhard A1 - Bruno, Giovanni T1 - In-situ pore size investigations of loaded porous concrete with non-destructive methods JF - Cement and Concrete Research N2 - Subject of this investigation is the in-situ evolution of pore volume and pore size distribution in Ytong (a porous concrete material) under increasing pressure with two different non-destructive analytical methods: Nuclear Magnetic Resonance (NMR) and X-ray Computed Tomography (CT). For both methods special strain devices to apply external pressure were constructed. The results from the two techniques yield complementary information on the pore size distribution and allows covering different pore size regions. KW - Pore size KW - Porous concrete KW - Computed tomography KW - Nuclear magnetic resonance PY - 2018 DO - https://doi.org/10.1016/j.cemconres.2018.06.008 SN - 0008-8846 SN - 1873-3948 VL - 111 SP - 72 EP - 80 PB - Elsevier Ltd. AN - OPUS4-45617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - 2D and 3D imaging chracterization techniques for porous ceramics N2 - The combination of microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on porous material properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of porosity in ceramics. Moreover, I will show how not-so-novel 2D characterization techniques, based X-ray refraction, can allow a great deal of insights in the damage evolution in microcracked (and porous) ceramics. I will show how X-ray refraction can detect objects (e.g. microcracks) below its own spatial resolution. Finally, I will discuss the link between the microstructural findings and the mechanical properties of porous microcracked ceramics. T2 - CIMTEC 2018 CY - Perugia, Italy DA - 04.06.2018 KW - Orientation KW - Cordierite KW - Beta-eucrytite KW - Porosity KW - Microcracking KW - Computed tomography KW - X-ray refraction PY - 2018 AN - OPUS4-45119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Magkos, Sotirios A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Direct iterative reconstruction of computed tomography trajectories: Reconstruction from limited number of projections with DIRECTT JF - Review of scientific instruments N2 - X-ray computed tomography has many applications in materials science and non-destructive testing. While the standard filtered back-projection reconstruction of the radiographic data sets is fast and simple, it typically fails in returning accurate results from missing or inconsistent projections. Among the alternative techniques that have been proposed to handle such data is the Direct Iterative REconstruction of Computed Tomography Trajectories (DIRECTT) algorithm. We describe a new approach to the algorithm, which significantly decreases the computational time, while achieving a better reconstruction quality than that of other established algorithms. KW - Computed tomography KW - DIRECTT KW - Iterative reconstruction KW - Limited data PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514403 DO - https://doi.org/10.1063/5.0013111 SN - 0034-6748 VL - 91 IS - 10 SP - 103107-1 EP - 103107-8 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-51440 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D A1 - Koptyug, A. A1 - Manabaev, K. A1 - Léonard, Fabien A1 - Mishurova, Tatiana A1 - Bruno, Giovanni A1 - Cheneler, D. A1 - Loza, K. A1 - Epple, M. A1 - Surmenev, R. A1 - Surmeneva, M. T1 - The impact of post manufacturing treatment of functionally graded Ti6Al4V scaffolds on their surface morphology and mechanical strength JF - Journal of Material Research and Technology N2 - An ultrasonic vibration post-treatment procedure was suggested for additively manufac-tured lattices. The aim of the present research was to investigate mechanical properties andthe differences in mechanical behavior and fracture modes of Ti6Al4V scaffolds treated withtraditional powder recovery system (PRS) and ultrasound vibration (USV). Scanning electronmicroscopy (SEM) was used to investigate the strut surface and the fracture surface mor-phology. X-ray computed tomography (CT) was employed to evaluate the inner structure,strut dimensions, pore size, as well as the surface morphology of additively manufacturedporous scaffolds. Uniaxial compression tests were conducted to obtain elastic modulus,compressive ultimate strength and yield stress. Finite element analysis was performedfor a body-centered cubic (BCC) element-based model and for CT-based reconstructiondata, as well as for a two-zone scaffold model to evaluate stress distribution during elasticdeformation. The scaffold with PRS post treatment displayed ductile behavior, while USVtreated scaffold displayed fragile behavior. Double barrel formation of PRS treated scaffoldwas observed during deformation. Finite element analysis for the CT-based reconstructionrevealed the strong impact of surface morphology on the stress distribution in comparisonwith BCC cell model because of partially molten metal particles on the surface of struts,which usually remain unstressed. KW - Additive manufacturing KW - Electron beam melting KW - Computed tomography KW - FEM KW - Lattice structures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505960 DO - https://doi.org/10.1016/j.jmrt.2019.12.019 SN - 2238-7854 VL - 9 IS - 2 SP - 1866 EP - 1881 PB - Elsevier B.V. AN - OPUS4-50596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schob, D. A1 - Roszak, R. A1 - Sagradov, I. A1 - Sparr, H. A1 - Ziegenhorn, M. A1 - Kupsch, Andreas A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Experimental determination and numerical simulation of material and damage behaviour of 3D printed polyamide 12 under quasi-static loading JF - Archives of Mechanics N2 - In order to characterise the material and damage behaviour of additively manufactured polyamide 12 (PA12) under quasi-static load and to implement it in a numerical model, experiments under quasi-static load as well as microstructural investigations were carried out. Selective laser sintering (SLS) was used as the manufacturing process. For the classification of the material behaviour, quasi-static cyclic tests with holding times as well as tensile tests were performed. X-ray refraction and computed tomography (CT) were used to investigate the damage behaviour. The Chaboche model, which has already been applied for metallic materials under thermomechanical loading, served as the basis for the selection of the numerical material model. The same procedure was used for the selection of the damage model, where the Gurson–Tvergaard–Needleman (GTN) model was chosen, which was already used for porous metallic materials. The Chaboche model shows very good agreement with experimental results. Furthermore, the coupling with the GTN model allows a very good modelling of the damage behaviour. Finally, it could be shown that the selected models are suitable to simulate the material and damage behaviour of 3D printed PA12. KW - Polyamide 12 KW - 3D printing KW - Viscoplastic KW - Chaboche model KW - Damage KW - GTN model KW - X-ray refraction KW - Computed tomography PY - 2019 DO - https://doi.org/10.24423/aom.3162 SN - 0373-2029 VL - 71 IS - 4-5 SP - 507 EP - 526 PB - IPPT PAN - Polish Academy of Sciences, Institute of Fundamental Technological Research CY - Warsaw AN - OPUS4-49409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schob, D. A1 - Sagradov, I. A1 - Roszak, R. A1 - Sparr, H. A1 - Franke, R. A1 - Ziegenhorn, M. A1 - Kupsch, Andreas A1 - Léonard, Fabien A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Experimental determination and numerical simulation of material and damage behaviour of 3D printed polyamide 12 under cyclic loading JF - Enginnering Fracture Mechanics N2 - The material and damage behaviour of additively manufactured polyamide 12 under cyclic loading was characterized by cyclic tests and microstructure analysis by using microscopy, X-ray refraction, and computed tomography. The results were used to determine parameters for the viscoplastic material model by Chaboche and a damage model by Gurson-Tvergaard-Needleman. The temperature was monitored during the experiments and the self-heating effect was observed. By including this effect, a higher accuracy could be achieved with the results of mechanical experiments. KW - 3D printing Polyamide 12 KW - Chaboche model KW - GTN model KW - Material and damage behaviour KW - X-ray refraction KW - Computed tomography PY - 2020 DO - https://doi.org/10.1016/j.engfracmech.2019.106841 SN - 0013-7944 VL - 229 SP - 106841-1 EP - 106841-13 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-50557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evsevleev, Sergei A1 - Paciornik, S. A1 - Bruno, Giovanni T1 - Advanced Deep Learning-Based 3D Microstructural Characterization of Multiphase Metal Matrix Composites JF - Advanced Engineering Materials N2 - The quantitative analysis of microstructural features is a key to understanding the micromechanical behavior of metal matrix composites (MMCs), which is a premise for their use in practice. Herein, a 3D microstructural characterization of a five-phase MMC is performed by synchrotron X-ray computed tomography (SXCT). A workflow for advanced deep learning-based segmentation of all individual phases in SXCT data is shown using a fully convolutional neural network with U-net architecture. High segmentation accuracy is achieved with a small amount of training data. This enables extracting unprecedently precise microstructural parameters (e.g., volume fractions and particle shapes) to be input, e.g., in micromechanical models. KW - Computed tomography KW - Convolutional neural networks KW - Deep learning KW - Metal matrix composites KW - Segmentations PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504261 DO - https://doi.org/10.1002/adem.201901197 SN - 1438-1656 VL - 22 IS - 4 SP - 1901197 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-50426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evsevleev, Sergei A1 - Cabeza, S. A1 - Mishurova, Tatiana A1 - Garcés, G. A1 - Sevostianov, I. A1 - Requena, G. A1 - Boin, M. A1 - Hofmann, M. A1 - Bruno, Giovanni T1 - Stress-induced damage evolution in cast AlSi12CuMgNi alloy with one and two ceramic reinforcements. Part II: Effect of reinforcement orientation JF - Journal of Materials Science N2 - While there is a large body of literature on the micro-mechanical behavior of metal matrix composites (MMCs) under uniaxial applied stress, very little is available on multi-phase MMCs. In order to cast light on the reinforcement mechanisms and damage processes in such multi-phase composites, materials made by an Al-based piston alloy and containing one and two ceramic reinforcements (planar-random oriented alumina fibers and SiC particles) were studied. In-situ compression tests during neutron diffraction experiments were used to track the load transfer among phases, while X-ray computed tomography on pre-strained samples was used to monitor and quantify damage. We found that damage progresses differently in composites with different orientations of the fiber mat. Because of the presence of intermetallic network, it was observed that the second ceramic reinforcement changed the load transfer scenario only at very high applied load, when also intermetallic particles break. We rationalized the present results combining them with previous investigations and using a micromechanical model. KW - Multi-phase KW - Metal matrix composites KW - Intermetallics KW - Computed tomography KW - In-situ neutron diffraction KW - Piston alloy KW - Load transfer PY - 2020 DO - https://doi.org/10.1007/s10853-019-04069-4 SN - 1573-4803 VL - 55 IS - 3 SP - 1049 EP - 1068 PB - Springer AN - OPUS4-49460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Powierza, Bartosz A1 - Gollwitzer, C. A1 - Wolgast, D. A1 - Staude, A. A1 - Bruno, Giovanni T1 - Fully experiment-based evaluation of few digital volume correlation techniques JF - Review of Scientific Instruments N2 - Digital Volume Correlation (DVC) is a powerful set of techniques used to compute the local shifts of 3D images obtained, for instance, in tomographic experiments. It is utilized to analyze the geometric changes of the investigated object as well as to correct the corresponding image misalignments for further analysis. It can therefore be used to evaluate the local density changes of the same regions of the inspected specimens, which might be shifted between measurements. In recent years, various approaches and corresponding pieces of software were introduced. Accuracies for the computed shift vectors of up to about 1‰of a single voxel size have been reported. These results, however, were based either on synthetic datasets or on an unrealistic setup. In this work, we propose two simple methods to evaluate the accuracy of DVC-techniques using more realistic input data and apply them to several DVC programs. We test these methods on three materials (tuff, sandstone, and concrete) that show different contrast and structural features. KW - DVC KW - Finite-element analysis KW - Image processing KW - Stress strain relations KW - Computed tomography PY - 2019 DO - https://doi.org/10.1063/1.5099572 SN - 1089-7623 VL - 90 IS - 11 SP - 115105 PB - AIP Publishing AN - OPUS4-49671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Berndard, D. A1 - Léonard, Fabien A1 - Plougonven, E. A1 - Bruno, Giovanni T1 - On the use of autocorrelation functions, permeability tensors, and computed tomography to characterise the anisotropy of diesel particulate filter materials JF - Philosophical Magazine N2 - We show how the combination of the spatial autocorrelation function and permeability calculations, applied to 3D X-ray computed tomography data, can yield quantitative information on the anisotropy of both meso-structure and fluid flow in Diesel Particulate Filter (DPF) materials, such as Cordierite and SiC. It was found that both the degree of anisotropy, and the orientation of the permeability and meso-structure are similar, but not identical. We confirm that the morphological anisotropy of cordierite materials is weak, and clearly influenced by the extrusion process that determines the main direction of anisotropy. Properties of the autocorrelation function are discussed and it is shown why estimating the characteristic length of real meso-structures (grain or ?pore? size) is not possible. Finally, we show that the autocorrelation function applied on grey-level images can give a good estimate of the degree of anisotropy even with limited resolution. KW - Anisotropy KW - Autocorrelation function KW - Computed tomography KW - Permeability tensor KW - Diesel particulates filter KW - Ceramics PY - 2020 DO - https://doi.org/10.1080/14786435.2020.1798532 SN - 1478-6435 VL - 100 IS - 22 SP - 2802 EP - 2835 PB - Taylor & Francis AN - OPUS4-52291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Garces, G. A1 - Requena, G. A1 - Bruno, Giovanni A1 - Sevostianov, I. T1 - Stress-induced damage evolution in cast AlSi12CuMgNi alloy with one- and two ceramic reinforcements JF - Journal of Material Science N2 - Two composites, consisting of an as-cast AlSi12CuMgNi alloy reinforced with 15%vol. Al2O3 short fibres and with 7%vol. Al2O3 short fibres + 15%vol. SiC particles were studied. Synchrotron computed tomography disclosed distribution, orientation, and volume fraction of the different phases. In-situ compression tests during neutron diffraction in direction parallel to the fibres plane revealed the load partition between phases. Internal damage (fragmentation) of the Si phase and Al2O3 fibres was directly observed in CT reconstructions. Significant debonding between Al-matrix and SiC particles was also found. Finally, based on the Maxwell scheme, a micro-mechanical model was utilized for the new composite with two ceramic reinforcements; it rationalizes the experimental data, and predicts the evolution of all internal stress components in each phase. KW - Computed tomography KW - Metal matrix composite KW - Load partition KW - Neutron diffraction PY - 2017 DO - https://doi.org/10.1007/s10853-017-1182-7 SN - 0022-2461 SN - 1573-4803 VL - 52 IS - 17 SP - 10198 EP - 10216 PB - Springer AN - OPUS4-40572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khrapov, D. A1 - Surmeneva, M. A1 - Koptioug, A. A1 - Evsevleev, Sergei A1 - Léonard, Fabien A1 - Bruno, Giovanni A1 - Surmenev, R. T1 - X-ray computed tomography of multiple-layered scaffolds with controlled gradient cell lattice structures fabricated via additive manufacturing JF - Journal of Physics Conference Series N2 - In this paper we report on the characterization by X-ray computed tomography of calcium phosphate (CaP) and polycaprolactone (PCL) coatings on Ti-6Al-4V alloy scaffolds used as a material for medical implants. The cylindrical scaffold has greater porosity of the inner part than the external part, thus, mimicking trabecular and cortical bone, respectively. The prismatic scaffolds have uniform porosity. Surface of the scaffolds was modified with calcium phosphate (CaP) and polycaprolactone (PCL) by dip-coating to improve biocompatibility and mechanical properties. Computed tomography performed with X-ray and synchrotron radiation revealed the defects of structure and morphology of CaP and PCL coatings showing small platelet-like and spider-web-like structures, respectively. KW - Additive manufacturing KW - Lattice structure KW - Multiple-layered scaffold KW - Coating KW - Medical implants KW - Computed tomography KW - Polycaprolactone KW - Calcium phosphate PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-471931 UR - http://stacks.iop.org/1742-6596/1145/i=1/a=012044 DO - https://doi.org/10.1088/1742-6596/1145/1/012044 SN - 1742-6596 VL - 1145 SP - 012044, 1 EP - 7 PB - IOP AN - OPUS4-47193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Absorption and refraction tomography: Characterization and non-destructive testing of micro-structured materials N2 - The combination of tomographic, microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on material and component properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. This logic thread equally holds for industrial and academic research, and valorizes expensive experiments such as those carried out at synchrotron sources, which cannot be daily repeated. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of damage evolution and microstructural properties, as well as for non-destructive testing. Examples of micro-structured inhomogeneous materials will be given, such as Composites, Ceramics, Concrete, and Additively manufactured parts. I will also show how X-ray refraction computed tomography (CT) can be highly complementary to classic absorption CT, being sensitive to internal interfaces. Additionally, I will present a new technique in our portfolio, Neutron Diffraction, which is extremely well suited to the study of internal stresses, both residual and under external load. T2 - Kolloquium ICMCB Bordeaux CY - Bordeaux, France DA - 13.07.2017 KW - Computed tomography KW - X-ray refraction KW - Neutron diffraction KW - Additive manufacturing KW - Ceramics KW - Composites KW - BAM PY - 2017 AN - OPUS4-41041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Rachmatulin, Natalia A1 - Fontana, Patrick A1 - Oesch, Tyler A1 - Bruno, Giovanni A1 - Radi, E. A1 - Sevostianov, I. T1 - Evaluation of the probability density of inhomogeneous fiber orientations by computed tomography and its application to the calculation of the effective properties of a fiber-reinforced composite JF - International Journal of Engineering Science N2 - This paper focuses on the experimental evaluation of one of the key microstructural Parameters of a short-fiber reinforced composite – the orientation distribution of fibers. It is shown that computed tomography (CT) produces results suitable for reconstruction of the orientation distribution function. This function is used for calculation of the effective elastic properties of polymer-fiber reinforced concrete. Explicit formulas are derived for overall elastic moduli accounting for orientation distribution in the frameworks of the noninteraction approximation, the Mori–Tanaka–Benveniste scheme, and the Maxwell scheme. The approach illustrated can be applied to any kind of composite material. KW - Computed tomography KW - Orientation distribution KW - Effective properties KW - Fiber-reinforced composite PY - 2018 DO - https://doi.org/10.1016/j.ijengsci.2017.10.002 SN - 0020-7225 SN - 1879-2197 VL - 122 SP - 14 EP - 29 PB - Elsevier AN - OPUS4-42814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evsevleev, Sergei A1 - Mishurova, Tatiana A1 - Cabeza, Sandra A1 - Koos, R. A1 - Sevostianov, I. A1 - Garces, G. A1 - Requena, G. A1 - Fernández, R. A1 - Bruno, Giovanni T1 - The role of intermetallics in stress partitioning and damage evolution of AlSi12CuMgNi alloy JF - Materials Science & Engineering A N2 - Load partitioning between phases in a cast AlSi12CuMgNi alloy was investigated by in-situ compression test during neutron diffraction experiments. Computed tomography (CT) was used to determine volume fractions of eutectic Si and intermetallic (IM) phases, and to assess internal damage after ex-situ compression tests. The CT reconstructed volumes showed the interconnectivity of IM phases, which build a 3D network together with eutectic Si. Large stresses were found in IMs, revealing their significant role as a reinforcement for the alloy. An existing micromechanical model based on Maxwell scheme was extended to the present case, assuming the alloy as a three-phase composite (Al matrix, eutectic Si, IM phases). The model agrees well with the experimental data. Moreover, it allows predicting the principal stresses in each phase, while experiments can only determine stress differences between the axial and radial sample directions. Finally, we showed that the addition of alloying elements not only allowed developing a 3D interconnected network, but also improved the strength of the Al matrix, and the ability of the alloy constituents to bear mechanical load. KW - Aluminum alloys KW - Neutron diffraction KW - Micromechanical modeling KW - Internal stress KW - Computed tomography PY - 2018 DO - https://doi.org/10.1016/j.msea.2018.08.070 VL - 736 SP - 453 EP - 464 PB - Elsevier B.V. AN - OPUS4-45927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Thiede, Tobias A1 - Serrano Munoz, Itziar A1 - Léonard, Fabien A1 - Farahbod, L. T1 - Computed tomography of LBM produced In625 lattices: Integrity analysis from powder particles to structures N2 - We investigated lattice structure manufactured by laser beam melting with computed tomography on difference scales, such as powder scale, strut scale and lattice scale. The raw powder has been evaluated by means of synchrotron computed tomography (CT) at the BAM-Line (HZB Bessy II, Berlin). Therefore, the particle size distribution and even the pore size distribution was investigated and compared with results received by the producer by means of sieving. Studies with laboratory X-ray CT of porosity and roughness of manufactured struts in dependence of the build angle exhibited the tendency that elongated pores appear solely in a certain range near the edge. The integrity and load-bearing capacity of a lattice structure was investigated by means of in-situ CT during compression. The lattice structure was compressed by 10 % in height with an applied maximum force of 5 kN. We applied digital volume correlation algorithm on volumes of different load steps to quantifies the displacement within the structure. T2 - Metallographie-Tagung 2018 CY - Leoben, Austria DA - 19.09.2018 KW - Additive manufacturing KW - Laser beam melting KW - Computed tomography KW - Lattice structures KW - In-situ CT KW - Porosity KW - Roughness PY - 2018 AN - OPUS4-45998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cabeza, S. A1 - Bruno, Giovanni A1 - Mishurova, Tatiana A1 - Garces, G. A1 - Requena, G. T1 - Damage evolution of Al matrix 4-phase composite N2 - The evolution of the microstructure of multiphase metal matrix composite AlSi12CuNiMg with 7% vol. Al2O3 + 15% vol. SiC (short fibers and whiskers, respectively) was studied by synchrotron computed tomography. It comprehended as cast and after heat treatment conditions, as well as damage evaluation after ex-situ compression tests at room temperature. The volume fraction of different phases, their distribution, their orientation, and damage events are studied. The influence on mechanical properties of the orientation of the planar random short fibres Al2O3 towards loading was investigated. Phase-specific load partition analysis for samples with fiber plane parallel and orthogonal to load, respectively, was performed by means of neutron diffraction (ND) during in-situ compression tests at room temperature. ND results proved that damage occurrence in the fillers strongly depends on the preferential orientation of those, playing a crucial role in the failure of the sample. The computed tomography observations confirm the damage observations from curves of load partition analysis of each phase. T2 - FiMPART 2017 CY - Bordeaux, France DA - 9.7.2017 KW - Composites KW - Aluminium matrix KW - Neutron diffraction KW - Computed tomography PY - 2017 AN - OPUS4-41109 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Trofimov, A. A1 - Mishurova, Tatiana A1 - Lanzoni, L. A1 - Radi, E. A1 - Bruno, Giovanni A1 - Sevostianov, I. T1 - Microstructural analysis and mechanical properties of concrete reinforced with polymer short fibers JF - International journal of engineering science N2 - The paper focuses on the development of a methodology for quantitative characterization of a concrete containing polymer fibers and pores. Computed tomography (CT) characterization technique is used to provide input data for Finite Element Method (FEM) simulations and analytical modeling based on micromechanical homogenization via the compliance contribution tensor formalism. Effective elastic properties of reinforced concrete are obtained experimentally using compression testing, analytically in the framework of Non-Interaction approximation and numerically performing direct FEM simulations on specimen with reconstructed microstructure. It is shown that CT produces results suitable for implementation in numerical and analytical models. The results of analytical and numerical modeling are in a good agreement with experimental measurements providing maximum discrepancy of ∼ 2.5%. KW - Reinforced concrete KW - Computed tomography KW - Finite element method KW - Micromechanics KW - Homogenization PY - 2018 DO - https://doi.org/10.1016/j.ijengsci.2018.09.009 SN - 0020-7225 SN - 1879-2197 VL - 133 SP - 210 EP - 218 PB - Elsevier AN - OPUS4-46153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - New aspects about the search for the most relevant parameters optimizing SLM materials JF - Additive Manufacturing N2 - While the volumetric energy density is commonly used to qualify a process parameter set, and to quantify its influence on the microstructure and performance of additively manufactured (AM) materials and components, it has been already shown that this description is by no means exhaustive. In this work, new aspects of the optimization of the selective laser melting process are investigated for AM Ti-6Al-4V. We focus on the amount of near-surface residual stress (RS), often blamed for the failure of components, and on the porosity characteristics (amount and spatial distribution). First, using synchrotron x-ray diffraction we show that higher RS in the subsurface region is generated if a lower energy density is used. Second, we show that laser de-focusing and sample positioning inside the build chamber also play an eminent role, and we quantify this influence. In parallel, using X-ray Computed Tomography, we observe that porosity is mainly concentrated in the contour region, except in the case where the laser speed is small. The low values of porosity (less than 1%) do not influence RS. KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Computed tomography PY - 2019 DO - https://doi.org/10.1016/j.addma.2018.11.023 SN - 2214-8604 VL - 25 SP - 325 EP - 334 PB - Elsevier AN - OPUS4-46737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Rehmer, Birgit A1 - Haubrich, J. A1 - Avila, Luis A1 - Schoenstein, F. A1 - Serrano Munoz, Itziar A1 - Requena, G. A1 - Bruno, Giovanni T1 - Separation of the impact of residual stress and microstructure on the fatigue performance of LPBF Ti-6Al-4V at elevated temperature JF - International Journal of Fatigue N2 - Manufacturing defects, high residual stress (RS), and microstructures affect the structural integrity of laser powder bed fusion (LPBF) Ti-6Al-4V. In this study, the individual effect of these factors on fatigue performance at elevated temperature (300 °C) was evaluated. Material in as-built condition and subjected to post-processing, including two heat treatments and hot isostatic pressing, was investigated. It was found that in the absence of tensile RS, the fatigue life at elevated temperature is primary controlled by the defects; and densification has a much stronger effect than the considered heat treatments on the improvement of the mechanical performance. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Fatigue performance KW - Computed tomography PY - 2021 DO - https://doi.org/10.1016/j.ijfatigue.2021.106239 SN - 0142-1123 VL - 148 SP - 106239 PB - Elsevier Ltd. AN - OPUS4-52369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano, Itziar A1 - Müller, Bernd A1 - Kupsch, Andreas A1 - Bruno, Giovanni A1 - Laquai, Rene' T1 - X-ray refractio techniques non-destructively quantify and classify defects in am materials N2 - X-ray refraction is analogous to visible light deflection by matter; it occurs at boundaries between different media. The main difference between visible light and X-rays is that in the latter case deflection angles are very small, from a few seconds to a few minutes of arc (i.e., the refraction index n is near to 1). Importantly, deflection of X-rays is also sensitive to the orientation of the object boundaries. These features make X-ray refraction techniques extremely suitable to a) detect defects such as pores and microcracks and quantify their densities in bulk (not too heavy) materials, and b) evaluate porosity and particle properties such as orientation, size, and spatial distribution (by mapping). While X-ray refraction techniques cannot in general image single defects, they can detect objects with size above a few wavelengths of the radiation. Such techniques, especially at the Synchrotron BESSY II, Berlin, Germany, can be used in-situ, i.e. when the specimen is subjected to temperatures or external loads. The use of X-ray refraction analysis yields quantitative information, which can be directly input in kinetics, mechanical and damage models. We hereby show the application of non-destructive X-ray refraction radiography (SXRR, 2D mapping also called topography) to problems in additive manufacturing: 1) Porosity analysis in PBF-LM-Ti64. Through the use of SXRR, we could not only map the (very sparse) porosity distribution between the layers and quantify it, but also classify, and thereby separate, the filled porosity (unmolten powder) from the keyhole and gas pores (Figure 1). 2) In-situ heat treatment of laser powder bed fusion PBF-LM-AlSi10Mg to monitor microstructure and porosity evolution as a function of temperature (Figure 2). By means of SXRR we indirectly observed the initial eutectic Si network break down into larger particles as a function of increasing temperature. We also could detect the thermally induced porosity (TIP). Such changes in the Si-phase morphology upon heating is currently only possible using scanning electron microscopy, but with a much smaller field-of-view. SXRR also allows observing the growth of some individual pores, usually studied via X-ray computed tomography, but again on much smaller fields-of-view. Our results show the great potential of in-situ SXRR as a tool to gain in-depth knowledge of the defect distribution and the susceptibility of any material to thermally induced damage and/or microstructure evolution over statistically relevant volumes. T2 - AAMS 2023 CY - Madrid, Spain DA - 27.09.2023 KW - X-ray Refaction radiography KW - Defects KW - Large Scale Facilities KW - Computed tomography PY - 2023 AN - OPUS4-58508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Alekseychuk, V. O. A1 - Kupsch, Andreas A1 - Plotzki, D. A1 - Bellon, Carsten A1 - Bruno, Giovanni T1 - Simulation-Assisted Augmentation of Missing Wedge and Region-of-Interest Computed Tomography Data JF - Journal of Imaging N2 - This study reports a strategy to use sophisticated, realistic X-ray Computed Tomography (CT) simulations to reduce Missing Wedge (MW) and Region-of-Interest (RoI) artifacts in FBP (Filtered Back-Projection) reconstructions. A 3D model of the object is used to simulate the projections that include the missing information inside the MW and outside the RoI. Such information augments the experimental projections, thereby drastically improving the reconstruction results. An X-ray CT dataset of a selected object is modified to mimic various degrees of RoI and MW problems. The results are evaluated in comparison to a standard FBP reconstruction of the complete dataset. In all cases, the reconstruction quality is significantly improved. Small inclusions present in the scanned object are better localized and quantified. The proposed method has the potential to improve the results of any CT reconstruction algorithm. KW - Computed tomography KW - Missing wedge KW - Region of interest KW - Augmented data KW - CT simulation KW - aRTist PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593799 UR - https://www.mdpi.com/2313-433X/10/1/11 DO - https://doi.org/10.3390/jimaging10010011 SN - 2313-433X VL - 10 IS - 1 SP - 1 EP - 15 PB - MDPI CY - Basel AN - OPUS4-59379 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Müller, Bernd R. A1 - Laquai, René A1 - Kupsch, Andreas A1 - Wieder, Frank A1 - Benemann, Sigrid A1 - Wilbig, Janka A1 - Günster, Jens A1 - Bruno, Giovanni T1 - Microstructural characterization of AP40 apatite-wollastonite glass-ceramic JF - Ceramics international N2 - The microstructure of an apatite-wollastonite (code name AP40) glass-ceramic is analyzed in this study by combining 2D microscopy, phase analysis, X-ray absorption and synchrotron X-ray refraction computed tomography (XCT and SXRCT, respectively). It is shown that this combination provides a useful toolbox to characterize the global microstructure in a wide scale range, from sub-micrometer to millimeter. The material displays a complex microstructure comprising a glassy matrix with embedded fluorapatite and wollastonite small crystals. In this matrix, large (up to 200 μm) spike-shaped structures are distributed. Such microstructural features are oriented around a central sphere, thereby forming a structure resembling a sea urchin. A unique feature of SXRCT, in contrast to XCT, is that internal interfaces are visualized; this allows one to show the 3D distribution of these urchins with exceptionally good contrast. Furthermore, it is revealed that the spike-shaped structures are not single crystals, but rather composed of sub-micrometric crystals, which are identified as fluorapatite and diopside phases by SEM-EDX analysis. KW - Glass-ceramic KW - X-ray refraction KW - Computed tomography KW - Microstructure PY - 2023 DO - https://doi.org/10.1016/j.ceramint.2022.12.130 SN - 0272-8842 VL - 49 IS - 8 SP - 12672 EP - 12679 PB - Elsevier Science CY - Amsterdam AN - OPUS4-57452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ulbricht, Alexander A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Oster, Simon A1 - Maierhofer, Christiane A1 - Bruno, Giovanni ED - Czujko, T. ED - Benedetti, M. T1 - Can Potential Defects in LPBF Be Healed from the Laser Exposure of Subsequent Layers? A Quantitative Study JF - Metals N2 - Additive manufacturing (AM) of metals and in particular laser powder bed fusion (LPBF) enables a degree of freedom in design unparalleled by conventional subtractive methods. To ensure that the designed precision is matched by the produced LPBF parts, a full understanding of the interaction between the laser and the feedstock powder is needed. It has been shown that the laser also melts subjacent layers of material underneath. This effect plays a key role when designing small cavities or overhanging structures, because, in these cases, the material underneath is feed-stock powder. In this study, we quantify the extension of the melt pool during laser illumination of powder layers and the defect spatial distribution in a cylindrical specimen. During the LPBF process, several layers were intentionally not exposed to the laser beam at various locations, while the build process was monitored by thermography and optical tomography. The cylinder was finally scanned by X-ray computed tomography (XCT). To correlate the positions of the unmolten layers in the part, a staircase was manufactured around the cylinder for easier registration. The results show that healing among layers occurs if a scan strategy is applied, where the orientation of the hatches is changed for each subsequent layer. They also show that small pores and surface roughness of solidified material below a thick layer of unmolten material (>200 µm) serve as seeding points for larger voids. The orientation of the first two layers fully exposed after a thick layer of unmolten powder shapes the orientation of these voids, created by a lack of fusion. KW - Computed tomography KW - Laser Powder Bed Fusion KW - In situ monitoring KW - infrared Thermography KW - Optical Tomography KW - Additive manufacturing KW - AISI 316L PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-528778 DO - https://doi.org/10.3390/met11071012 VL - 11 IS - 7 SP - 1012 PB - MDPI CY - Basel AN - OPUS4-52877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -