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 holds equally 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. T2 - Treffen der `Confindustria´(Industrieverband) CY - Potenza, Italien DA - 29.03.2016 KW - Tomographie KW - Refraktion KW - Neutronenbeugung KW - Additive Fertigung PY - 2016 AN - OPUS4-35700 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 - CONF A1 - Bruno, Giovanni T1 - Mechanical and thermal properties of aluminum titanate (AT) N2 - In this seminar I present the microstructure and micromechanical properties of diesel particulate filter materials, and then particularize them to porous microcracked aluminum titanate. I show that neutron diffraction is particularly suited for bulk studies, especially under applied load or at high temperatures. The combination of macroscopic and microscopic tests with modeling and simulation yields great added value to understand the mechanics of microcracking. T2 - Webinar DFG Hotmix CY - Online meeting DA - 14.06.2021 KW - Imaging KW - Neutron and X-ray Diffraction KW - Non-linear stress-strain KW - Anisotropy KW - Microcracking KW - Porosity PY - 2021 AN - OPUS4-52838 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Gollwitzer, Christian T1 - XCT discloses the Impact of Machining on Mechanical Properties of Diesel Particulate Filter Materials N2 - Microstructural changes in porous cordierite for diesel particulate filter applications caused by machining were characterized using microtensile testing and X-ray computed tomography (XCT). Young’s modulus was determined on ~215-380 m thick machined samples by digital image correlation. Results show a decrease of Young’s modulus due to machining of the thin samples. Explanation of this phenomenon was provided by XCT: the presence of debris due to machining and the variation of porosity due to removal of the outer layers were quantified and correlated with the introduction of further microcracking. T2 - ICT Conference 2018 CY - Wels, Austria DA - 06.02.2018 KW - Diesel Particulate Filter Materials KW - Mechanical Properties PY - 2018 AN - OPUS4-44778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Roveda, Ilaria A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Bruno, Giovanni T1 - Synchrotron X-ray refraction detects microstructure and porosity evolution during in-situ heat treatments N2 - For the first time, synchrotron X-ray refraction radiography (SXRR) has been paired with in-situ heat treatment to monitor microstructure and porosity evolution as a function of temperature. The investigated material was a laser powder bed fusion (LPBF) manufactured AlSi10Mg, where the initial eutectic Si network is known to disintegrate and spherodize into larger particles with increasing temperature. Such alloy is also prone to thermally induced porosity (TIP). We show that SXRR allows detecting the changes in the Si-phase morphology upon heating, while this is currently possible only using scanning electron microscopy. SXRR also allows observing the growth of pores, usually studied via X-ray computed tomography, but 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 susceptibility of any material to thermally induced damage and/or microstructure evolution over statistically relevant volumes. KW - Synchrotron X-ray refraction radiography KW - Si network disintegration KW - Thermally induced porosity (TIP) KW - Laser powder bed fusion (LPBF) KW - Statistically relevant volumes KW - AlSi10Mg alloy PY - 2022 DO - https://doi.org/10.1016/j.msea.2022.142732 SN - 0921-5093 VL - 838 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam AN - OPUS4-54297 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Morphological and crystallographic Anisotropy in porous ceramic N2 - In this talk, the morphological (pore space) and crystallographic (domain) anisotropy of porous ceramics fordiesel particulate filter applications are discussed. The influence of such microstructural feature on the macroiscopic properties at componnt level is also shown. T2 - MSCA Webinar CY - Online meeting DA - 05.12.2024 KW - Neutron Diffraction KW - Porosity KW - X-ray Computed Tomography KW - X-ray refraction radiography KW - Large Scale facilites PY - 2024 AN - OPUS4-62047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Fernández, R. A1 - Saliwan Neumann, Romeo A1 - González-Doncel, G. A1 - Bruno, Giovanni T1 - Dislocation structures after creep in an Al-3.85 %Mg alloy studied using EBSD-KAM technique N2 - The electron backscatter diffraction (EBSD) technique is used to investigate the dislocation structures formed after steady-state creep deformation of an Al-3.85%Mg alloy. This material is crept at two different stress levels, corresponding to the so-called power-law and power-law breakdown regimes. The results show that, regardless of the creep stress level, the strain tends to localize, leading to the formation of intragranular bands. The thickness of such bands is larger when the material is tested at loads corresponding to the power-law breakdown. This suggests enhanced diffusion by dislocation pipes. KW - Steady-state creep KW - Al-3.85%Mg alloy KW - Power-law breakdown KW - Electron backscatter diffraction (EBSD) KW - Denoising filter PY - 2023 DO - https://doi.org/10.1016/j.matlet.2023.133978 SN - 0167-577X VL - 337 SP - 1 EP - 4 PB - Elsevier B.V. AN - OPUS4-56941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - How 3D X-ray Imaging and Residual Stress Analysis contribute to safety of materials and structures N2 - The safety of materials and structures can be detrimentally influenced by residual stresses (RS) and defect populations (voids or other features leading to failure) if they are not correctly accounted for in the design. Therefore, the accurate characterization of these features and the consideration of their impact is crucial for the safe design of components. The ability to characterize these features non-destructively enables the direct correlation on resulting mechanical performance. 3D X-ray computed tomography (XCT) is used to resolve and quantitively analyze microstructural features (i.e., voids, porosity). This is often used to assess the capability of the manufacturing route, i.e., additive manufacturing (AM). The non-destructive nature of the method also enables the study of the evolution of damage in materials from such microstructural features [1]. Using in-situ methods such as compression or tension, the propagation of damage from initial microstructure can be assessed, aiding our understanding of which features are detrimental to safety [3]. Diffraction based residual stress analysis methods including high energy X-ray and neutron diffraction can be used to study the residual stress gradients from the surface, subsurface and into the bulk non-destructively. These methods can be used to study the influence of heat treatments on residual stress and can be combined with XCT results to correlate the interaction of residual stresses with microstructural features (i.e., void clusters). This talk will give an overview of the capabilities and opportunities of 3D XCT and diffraction based residual stress analysis to close the gap in our understanding of material degradation on mechanical performance, enabling manufacturers to adjust their designs accordingly for safety critical applications. A particular focus will be made on examples where the two advanced techniques are combined to enhance such understanding. T2 - MaterialsWeek 2025 CY - Frankfurt am Main, Germany DA - 02.04.2025 KW - Neutron Diffraction KW - Residual Stress KW - X-ray Computed Tomography KW - Additive Manufacturing KW - Large Scale facilites KW - Creep KW - Defects KW - BAMline PY - 2025 AN - OPUS4-62895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - X-ray Absorption and Refraction techniques for characterization and non-destructive-testing of 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 show how Neutron Diffraction, which is extremely well suited to the study of internal stresses, both residual and under external load, can well be coupled to the microstructural framework gained by CT, allowing understanding the microstructure-property relationships in materials. T2 - ENSAM CY - Paris, France DA - 28.11.2019 KW - Additive Manufacturing KW - Computed Tomography KW - Neutron Diffraction KW - X-ray refraction techniques KW - Composites PY - 2019 AN - OPUS4-49927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Bruno, Giovanni T1 - BAM activities in material characterization by advanced X-ray imaging N2 - The overview of the activity of Federal Institute for Material Research and Testing (BAM, Belin, Germany) in the field of additively manufacturing material characterization will be presented. The research of our group is focused on the 3D imaging of AM materials by means of X-ray Computed Tomography at the lab and at synchrotron, and the residual stress characterization by diffraction (nondestructive technique). Also, two successful research project in collaboration with CAM2, Sweden are presented. T2 - CAM2 Annual Meeting CY - Gothenburg, Sweden DA - 25.10.2023 KW - Additive manufacturing KW - Residual stress KW - X-ray computed tomography PY - 2023 AN - OPUS4-58828 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - X-Ray absorption, refraction, and diffraction techniques for the characterization and non-destructive testing of 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 show how Neutron Diffraction, which is extremely well suited to the study of internal stresses, both residual and under external load, can well be coupled to the microstructural framework gained by CT, allowing understanding the microstructure-property relationships in materials. T2 - VDI FA101- Anwendungsnahe zerstörungsfreie Werkstoff und Bauteilprüfung Jährliches Treffen CY - Berlin, Germany DA - 10.04.2025 KW - Neutron Diffraction KW - X-ray computed tomography KW - Large Scale Facilities KW - X-ray refraction radiography KW - BAMline PY - 2025 AN - OPUS4-62939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Mehta, B. A1 - Nyborg, L. A1 - Virtanen, E. A1 - Markötter, Henning A1 - Hryha, E. A1 - Bruno, Giovanni T1 - Failure Mechanisms Investigation by Means of in-situ Synchrotron Computed Tomography in Aluminum MMC-based Alloy Tailored for Additive Manufacturing (AM) N2 - The availability of high-performance Al alloys in AM is limited due to difficulties in printability, requiring both the development of synergetic material and AM process to mitigate problems such as solidification cracking during laser powder bed fusion (LPBF). The goal of this work was to investigate the failure mechanism in a LPBF 7017 Aluminium alloy + 3 wt% Zr + 0.5 wt% TiC. The processing leads to different categories of Zr-rich inclusions, precipitates and defects. T2 - Alloys for Additive Manufacturing Symposium 2022 (AAMS22) CY - Munich, Germany DA - 11.09.2022 KW - Additive manufacturing KW - Laser powder bed fusion KW - Synchrotron X-ray computed tomography KW - MMC PY - 2022 AN - OPUS4-56110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Kupsch, Andreas A1 - Serrano-Munoz, Itziar 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 holds equally 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. I will also show how X-ray refraction computed tomography (CT) can be highly complementary to classic absorption CT, being sensitive to internal interfaces. T2 - MPA Seminar 2024 CY - Stuttgart, Germany DA - 08.10.2024 KW - X-ray Refaction radiography KW - X-ray computed tomography KW - Damage KW - Composites KW - Large Scale facilites KW - Synchrotron PY - 2024 AN - OPUS4-61347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - X-ray refraction 2D and 3D techniques N2 - X-ray refraction techniques represent a very promising, yet not so wide-spread, set of X-ray techniques based on refraction effects. They allow determining internal specific surface (surface per unit volume) in a non-destructive fashion, position and orientation sensitive, and with nanometric detectability. While they are limited by the X-ray absorption of the material under investigation, we demonstrate showcases of ceramics and composite materials, where understanding of microstructural features could be achieved in a way unrivalled even by high-resolution techniques such as electron microscopy or computed tomography. T2 - ICTMS 2017 CY - Lund, Sweden DA - 26.06.2017 KW - X-ray refraction KW - Composites KW - Damage KW - Cracks KW - Cearmics PY - 2017 AN - OPUS4-41042 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 holds equally for industrial and academic research, and valorizes expensive experiments such as those carried out at synchrotron sources, which cannot be daily repeated. T2 - Meeting Digital Image and Volume Correlation CY - Milton Keynes, UK DA - 29.02.2016 KW - Non-destructive KW - Characterization KW - Zerstörungsfreie Prüfung PY - 2016 AN - OPUS4-35749 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Introduction to Residual Stress N2 - The determination of residual stress in additively manufactured materials is a challenge, even after decades from the establishment of the basics of residual stress analysis. This is due to the peculiar microstructure of such materials. In fact, researchers have discovered that conventional methods for the determination of RS in materials do not properly work for AM materials. In this tutorial, the basics of RS analysis will be explained, together with the basics of AM manufacturing techniques. The microstructure of the peculiar materials (AM) dealt with here will be elucidated. Successively, the necessary modifications to the conventional approaches to RS analysis will be explained and case studies will be displayed, for the attendant to touch with hands the peculiarities of the approaches. Finally, a few experimental and theoretical tips will be given on dos and don’ts for a correct determination of RS in AM materials. T2 - 11th European Conference on Residual Stresses (ECRS-11) CY - Prague, Czech Republic DA - 03.06.2024 KW - Neutron Diffraction KW - Residual Stress KW - Mechanical Properties KW - X-ray diffraction PY - 2024 AN - OPUS4-60422 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Jaenisch, Gerd-Rüdiger A1 - Bellon, Carsten A1 - Jaczinski, Jessica T1 - Virtual XCT - Simulation of Industrial XCT-Systems with aRTist N2 - One of the few 3D methods, that can be used to analyze an object non-destructively, is X-ray computed tomography (CT). The determination of the object's deviations, such as shape and the internal structure of objects, including defects and material degradation, is of particular interest to industry. The ability of CT to scan an object with its internal and external features at once causes increasing adoption in dimensional metrology. This includes the need to determine the measurement uncertainty. Experimental uncertainty determination by conducting repeated CT measurements is costly and time-consuming. The simulation of the CT measurement process offers the possibility of determining the task-specific measurement uncertainty numerically in a resource-efficient manner. There are already several software programs available that simulate CT systems, such as aRTist. Once the virtual replica of a CT system has been completed, it’s accuracy must be evaluated quantitively in comparison to the CT measurements. To focus on analyzing the quality of the simulated CT images different metrics are introduced for the comparison of experimental and simulated CT projections. The results of the comparisons are presented, and conclusions are drawn how to improve the simulation of industrial CT systems. T2 - MPA Seminar 2024 CY - Stuttgart, Germany DA - 08.10.2024 KW - X-ray Computed tomography KW - Simulations KW - Virtual XCT KW - Digital Twin PY - 2024 AN - OPUS4-61346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - BAM Characterization on Capabilities in Additive Manufacturing N2 - 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 damage evolution and microstructural properties, as well as for non-destructive testing, with particular focus on additively manufactured materials. I will also show how X-ray refraction computed tomography (CT) and Neutron diffraction can be highly complementary to classic absorption CT, being sensitive to internal interfaces and residual stress analysis, respectively. T2 - Treffen des Konsortium AeroMatForAM CY - Köln, Germany DA - 16.03.2017 KW - Neutronenbeugung KW - Eigenspannungen KW - Additive Fertigung KW - Computertomographie KW - Röntgenrefraktion KW - X-ray Refraction KW - Additive Manufacturing KW - Computed Tomography KW - Residual Stress analysis KW - Neutron Diffraction PY - 2017 AN - OPUS4-39657 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Cabeza, S. A1 - Bruno, Giovanni 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 - CONF A1 - Bruno, Giovanni T1 - X-ray Computed Tomography: Facts and Myths N2 - In this talk, I will describe the principle of Computed Tomography, explain its mathematical fundaments, show the artefacts occurring during data acquisition and give examples of applications. T2 - Chalmers Annual Meeting 2024 CY - Gothenburg, Sweden DA - 23.10.2024 KW - X-ray Computed tomography KW - Defects KW - Machine Learning KW - Reconstruction KW - Artefacts KW - Synchrotron PY - 2024 AN - OPUS4-61514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Cong A1 - Müller, Bernd R. A1 - Lebedev, O. A1 - Giovannelli, F. A1 - Bruno, Giovanni A1 - Delorme, F. T1 - Effects of impurities on the stability of the low thermal conductivity in Fe2TiO5 ceramics N2 - The stability of the low thermal conductivity in Fe2TiO5 pseudobrookite ceramics has been studied. An increase in thermal diffusivity is observed after only three cycles of measurement. X-ray refraction shows an increase in the mean value of specific surface after the thermal diffusivity measurements. By using scanning electron microscopy and high‐angle annular dark‐field scanning transmission electron microscope equipped with energy dispersive X-ray spectroscopy, we observe a segregation of Ca- and F-rich nanocrystals at grain boundaries after three cycles of thermal diffusivity measurement. Therefore, impurities seem to be more efficient to scatter phonons as point defects in the pseudobrookite lattice rather than as nanocrystals at pseudobrookite grain boundaries. This emphasizes the importance of precursor purity and the influence of redistribution of impurities on thermoelectric properties: stability of micro-/nano-structures is a key point, and repeated thermoelectric measurements may allow detecting such metastable micro- /nano-structures and producing stable and reliable data. KW - Fe2TiO5 KW - Impurity segregation KW - Thermoelectrics KW - X-ray refraction KW - Scanning transmission electron microscopy PY - 2019 UR - http://www.sciencedirect.com/science/article/pii/S1044580318329309 DO - https://doi.org/10.1016/j.matchar.2019.01.021 SN - 1044-5803 SN - 1873-4189 VL - 149 SP - 111 EP - 117 PB - Elsevier Inc. AN - OPUS4-47255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Capabilities at BAM, division 8.5- X-ray Imaging N2 - The X-ray computed tomography capabilities at BAM (especially in Division 8.5) are shown. It is also shown that the group possesses X-ray refraction radiography techniques, which are complementary to absorption radiography, and uses diffraction for residual stress analysis. Examples of applications in the field of Additive Manufacturing ale also shown. T2 - DGM AK XCT CY - Berlin, Germany DA - 27.11.2024 KW - X-ray Computed tomography KW - Defects KW - X-ray refraction radiography KW - Additive Manufacturing PY - 2024 AN - OPUS4-62046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Starting new adventures at BAM. The focus area projects PROMOAM and AGIL N2 - While additive manufacturing (AM) is blossoming in nearly every industrial field, and the most different process are being used to produce components and materials, little attention is paid on the safety concerns around AM materials and processes. Leveraging on our leading expertise in non-destructive testing (NDT) and materials characterization, we approach AM at BAM under two important viewpoints: first the on-line monitoring of the process and of the product, second the evolution of the (unstable) microstructure of AM materials under external loads. These two subjects are the core of the two new-born internal projects ProMoAM and AGIL, respectively. A detailed view of the goals and the organization of these two projects will be given, together with the expected output, and some preliminary results. T2 - Vortragsveranstaltung Bauhaus Universität, im Rahmen der Kolloquien der Fakultät Bauwesen. CY - Weimar, Germany DA - 01.06.2018 KW - Thermography KW - Additive Manufacturing KW - Non-destructive testing KW - On-line monitoring KW - Residual stress PY - 2018 AN - OPUS4-45118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zurcher, Theo A1 - Serrano-Munoz, Itziar A1 - Mishurova, Tatiana A1 - Abreu Faria, Guilherme A1 - Degener, Sebastian A1 - Fridrici, Vincent A1 - Charkaluk, Eric A1 - Bruno, Giovanni T1 - Sliding wear resistance and residual stresses of parts repaired by laser metal deposition N2 - Large temperature gradients inherent to additive manufacturing (AM) processes induce large residual stress (RS) in the final part. Because RS can influence the tribological properties, this study focuses on the relationship between wear sliding properties and RS in IN718 coatings. Such coatings were deposited with a Laser metal deposition (LMD) machine using two different scanning strategies. The wear resistance and RS state were investigated after surface milling. RS were measured before and after wear tests on a reciprocating sliding test apparatus. Two different X-ray diffraction techniques were employed to measure the surface and subsurface state RS: Laboratory Energy Dispersive X-ray Diffraction (LEDXD) and Synchrotron X-ray Energy Dispersive Diffraction (SXEDD). Due to the milling process, the coatings show similar depth distributions of RS from 22 to 92 μm depth, but exhibit different magnitudes depending on the scanning strategy used. Reciprocating sliding wear tests induced high compressive residual stresses that erased the initial RS state, and a similar wear behavior was observed in the two samples. These samples possess similar texture and grain morphology. This demonstrates that the influence of RS on wear resistance is a second-order effect. Nevertheless, it was observed that RS can still impact the wear performance at the early testing stages of the repaired parts. KW - Additive manufacturing KW - Wear resistance KW - Residual stress PY - 2023 DO - https://doi.org/10.1007/s10853-023-09129-4 SN - 0022-2461 SP - 1 EP - 18 PB - Springer AN - OPUS4-59084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Fritsch, Tobias A1 - Schröder, Jakob A1 - Mishurova, Tatiana A1 - Ulbricht, Alexander A1 - Evans, Alexander A1 - Serrano-Munoz, Itziar T1 - How to experimentally determine residual stress in AM structures N2 - The experimental determination of residual stress becomes more complicated with increasing complexity of the structures investigated. Unlike the conventional and most of the additive manufacturing (AM) fabrication techniques, laser powder bed fusion (PBF-LB) allows the production of complex structures without any additional manufacturing step. However, due to the extremely localized melting and solidification, internal stress-induced deformation and cracks are often observed. In the best case, significant residual stress is retained in the final structures as a footprint of the internal stress during manufacturing. Here we report solutions to the most prevalent challenges when dealing with the diffraction-based determination of residual stress in AM structures, in particular the choice of the correct diffraction elastic constants. We show that for Nickel-based alloys, the diffraction elastic constants of AM material significantly deviate from their conventional counterparts. Furthermore, measurement strategies to overcome the hurdles appearing when applying diffraction-based techniques to complex-shaped lattice structures are presented: a) proper sample alignment within the beam, b) the proper determination of the residual stress field in a representative part of the structure (i.e., with an engineering meaning). Beyond the principal stress magnitude, the principal direcions of residual stress are discussed for different geometries and scan strategies, as they are relevent for failure criteria. We show that the RS in the lattice struts can be considered to be uniaxial and to follow the orientation of the strut, while the RS in the lattice knots is more hydrostatic. Additionally, we show that strain measurements in at least seven independent directions are necessary for the correct estimation of the principal stress directions. The measurement directions should be chosen according to the sample geometry and to an informed choice on the possible strain field (i.e., reflecting the scan strategy). We finally show that if the most prominent direction is not measured, the error in the calculated stress magnitude increases in such a manner that no reliable assessment of RS state can be made. T2 - Additive 2024 CY - Berlin, Germany DA - 12.06.2024 KW - Neutron Diffraction KW - Residual Stress KW - X-ray Computed Tomography KW - Additive Manufacturing KW - Lattice Structure KW - Inconel PY - 2024 AN - OPUS4-60423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruno, Giovanni A1 - Kachanov, Mark T1 - Microstructure-property connections for porous ceramics: The possibilities offered by micromechanics N2 - Microstructure of porous ceramics is highly “irregular”: it comprises pores and microcracks of diverse shapes and orientations. This makes their quantitative modeling challenging, and one often resorts to empirical relations containing Fitting Parameters and having somewhat uncertain range of applicability. We review the substantial progress made in modeling of “irregular” microstructures that does not seem to have been sufficiently utilized in the context of ceramics. We discuss the possibilities offered by micromechanics in developing microstructure–property relations for porous microcracked ceramics. After an overview of relevant micromechanics topics, we focus on several issues of specific interest for ceramics: nonlinear stress–strain behavior, effective elastic properties, and thermally induced microcracking. We discuss extraction of microscale Parameters (such as strength of the intergranular cohesion, density of cracks and pores, etc.) from macroscopic data and identify the extent of uncertainty in this process. We also argue that there is no quantitative correlation between fracturing process and the loss of elastic stiffness. KW - Ceramics KW - Microcracking KW - Pores KW - Microstructure KW - Micromechanics KW - Intergranular strength KW - Nonlinearity KW - Stress– strain curves PY - 2016 DO - https://doi.org/10.1111/jace.14624 SN - 0002-7820 SN - 1551-2916 VL - 99 IS - 12 SP - 3829 EP - 3852 AN - OPUS4-39355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Absorbtion and Refraction Techniques: Characterization and Non-Destructive Testing of Additively Manufactured 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 holds equally 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. T2 - c-Kolloquium an dem FRM II Reaktor CY - Munich, Germany DA - 29.07.2016 KW - Computertomographie KW - Metrologie KW - 3D Mikrostruktur KW - Zerstörungsfreie Prüfung KW - Röntgenrefraktion KW - TF Material KW - Analytical Science PY - 2015 AN - OPUS4-38827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eddah, Mustapha A1 - Markötter, Henning A1 - Mieller, Björn A1 - Widjaja, Martinus Putra A1 - Beckmann, Jörg A1 - Bruno, Giovanni T1 - Multi-energy high dynamic range synchrotron X-ray computed tomography N2 - Synchrotron X-ray computed tomography (SXCT) is regularly used in materials science to correlate structural properties with macroscopic properties and to optimize manufacturing processes. The X-ray beam energy must be adapted to the sample properties, such as size and density. If both strongly and weakly absorbing materials are present, the contrast to the weakly absorbing materials is lost, resulting in image artifacts and a poor signal-tonoise ratio (SNR). One particular example is a low-temperature co-fired ceramics (LTCC), in which metal connections are embedded in a ceramic matrix and form 3-dimensional conducting structures. This article describes a method of combining SXCT scans acquired at different beam energies, significantly reducing metal artifacts, and improving image quality. We show how to solve the difficult task of merging the scans at low and high beam energy. Our proposed merging approach achieves up to 35 % improvement in SNR within ceramic regions adjacent to metallic conductors. In this way, previously inaccessible regions within the ceramic structure close to the metallic conductors are made accessible. The paper further discusses methodological requirements, limitations, and potential extensions of the presented multi-energy SXCT merging technique. KW - Synchrotron computed tomography KW - Reconstruction algorithm KW - High dynamic range KW - Data merging KW - Low-temperature cofired ceramics PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652339 DO - https://doi.org/10.1016/j.tmater.2025.100079 SN - 2949-673X VL - 9 SP - 1 EP - 10 PB - Elsevier CY - Amsterdam AN - OPUS4-65233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chi, J. A1 - Agea Blanco, B. A1 - Bruno, Giovanni A1 - Günster, Jens A1 - Zocca, Andrea T1 - Self-Organization Postprocess for Additive Manufacturingin Producing Advanced Functional Structure and Material N2 - Additive manufacturing (AM) is developing rapidly due to itsflexibility in producing complex geometries and tailored material compositions. However, AM processes are characterized by intrinsic limitations concerning their resolution and surface finish, which are related to the layer-by-layer stacking process. Herein, a self-organization process is promoted as an approach to improve surface quality and achieve optimization of 3D minimal surface lightweight structures. The self-organization is activated after the powder bed 3D printing process via local melting, thereby allowing surface tension-driven viscous flow.The surface roughness Ra (arithmetic average of the roughness profile) could bedecreased by a factor of 1000 and transparent lenses and complex gyroid structures could be produced for demonstration. The concept of self-organization is further elaborated by incorporating external magnetic fields to intentionally manipulate magnetic particles, which are mixed with the polymer before printing and self-organization. This concept can be applied to develop programmable materials with specific microtextures responding to the external physical conditions. KW - Additive Manufacturing KW - Self-organization KW - Triply Periodical Minimal Surface PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540588 DO - https://doi.org/10.1002/adem.202101262 VL - 24 IS - 6 SP - 1 EP - 8 PB - Wiley VCH AN - OPUS4-54058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hilgenberg, Kai A1 - Daum, Werner A1 - Maierhofer, Christiane A1 - Altenburg, Simon A1 - Bruno, Giovanni A1 - Heckel, Thomas A1 - Skrotzki, Birgit A1 - Zerbst, Uwe A1 - Kranzmann, Axel A1 - Bettge, Dirk A1 - Sommer, Konstantin A1 - Seeger, Stefan A1 - Nitsche, Michael A1 - Günster, Jens A1 - Evans, Alexander T1 - Additive manufacturing at the BAM: We focus on Safety N2 - In Germany, the Federal Institute for Materials Research and Testing (BAM) is addressing challenges in the implementation of additive manufacturing on the industrial landscape for safety-critical applications. KW - Process development KW - Additive Manufacturing KW - In-situ Process Monitoring KW - Non-destructive Materials KW - Characterisation KW - Safety KW - Fatigue KW - Environment KW - Standardisation PY - 2019 UR - https://static.asminternational.org/amp/201910/22/ SN - 0882-7958 VL - 177 IS - 7 SP - 22 EP - 26 PB - ASM International CY - Materials Park, OH, USA AN - OPUS4-49780 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 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 - Chen, Cong A1 - Müller, Bernd R. A1 - Prinz, Carsten A1 - Stroh, Julia A1 - Feldmann, Ines A1 - Bruno, Giovanni T1 - The correlation between porosity characteristics and the crystallographic texture in extruded stabilized aluminium titanate for diesel particulate filter applications N2 - Porous ceramic diesel particulate filters (DPFs) are extruded products that possess macroscopic anisotropic mechanical and thermal properties. This anisotropy is caused by both morphological features (mostly the orientation of porosity) and crystallographic texture. We systematically studied those two aspects in two aluminum titanate ceramic materials of different porosity using mercury porosimetry, gas adsorption, electron microscopy, X-ray diffraction, and X-ray refraction radiography. We found that a lower porosity content implies a larger isotropy of both the crystal texture and the porosity orientation. We also found that, analogous to cordierite, crystallites do align with their axis of negative thermal expansion along the extrusion direction. However, unlike what found for cordierite, the aluminium titanate crystallite form is such that a more pronounced (0 0 2) texture along the extrusion direction implies porosity aligned perpendicular to it. KW - Preferred orientation KW - X-ray refraction KW - Pore orientation KW - Crystal structure KW - Extrusion KW - Microstructure-property relations PY - 2020 DO - https://doi.org/10.1016/j.jeurceramsoc.2019.11.076 SN - 0955-2219 VL - 40 IS - 4 SP - 1592 EP - 1601 PB - Elsevier Ltd. AN - OPUS4-50325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Orientation of pore space in diesel particulate filter materials N2 - Porous ceramic diesel particulate filters (DPFs) are extruded products that possess macroscopic anisotropic mechanical and thermal properties. This anisotropy is caused by both morphologic features (mostly the orientation of porosity) and crystallographic texture. We systematically studied those two aspects in a cordierite and two aluminum titanate (AT) ceramic materials of different porosity using mercury porosimetry, gas adsorption, electron microscopy, X-ray diffraction, and X-ray refraction radiography. We found that a lower porosity in AT content implies a larger isotropy of both the crystal texture and the porous space orientation. We also found that, analogous to cordierite, AT crystallites do align with their axis of negative thermal expansion along the extrusion direction. However, unlike what found for cordierite, the aluminium titanate crystallite form is such that a more pronounced (0 0 2) texture along the extrusion direction implies porosity aligned perpendicular to it. T2 - 6th Cellular Materials CellMAT 2020 CY - Online meeting DA - 07.10.2020 KW - Microstructure-property relations KW - Preferred orientation KW - X-ray refraction KW - Pore orientation KW - Crystal structure KW - Extrusion PY - 2020 AN - OPUS4-51451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eddah, Mustapha A1 - Markötter, Henning A1 - Mieller, Björn A1 - Widjaja, Martinus Putra A1 - Beckmann, Jörg A1 - Bruno, Giovanni T1 - Multi-Energy High Dynamic Range (HDR) Synchrotron X-ray Computed Tomography applied to LTCC samples N2 - Synchrotron X-ray computed tomography (SXCT) is regularly used in materials science to correlate structural properties with macroscopic properties and to optimize manufacturing processes. The X-ray beam energy must be adapted to the sample properties, such as size and density. If both strongly and weakly absorbing materials are present, the contrast to the weakly absorbing materials is lost, resulting in image artifacts and a poor signal-to-noise ratio (SNR). One example is a low-temperature co-fired ceramics (LTCC), in which metal connections are embedded in a ceramic matrix and form 3-dimensional conducting structures. This article describes a method of combining SXCT scans acquired at different beam energies, significantly reducing metal artifacts, and improving image quality. We show how to solve the difficult task of merging the scans at low and high beam energy. Our proposed merging approach achieves up to 35% improvement in SNR within ceramic regions adjacent to metallic conductors. In this way, previously inaccessible regions within the ceramic structure close to the metallic conductors are made accessible. The paper further discusses methodological requirements, limitations, and potential extensions of the presented multienergy SXCT merging technique. T2 - iCT 2026 CY - Linz, Austria DA - 10.02.2026 KW - Synchrotron x-ray CT KW - Multi-energy CT KW - Low-Temperature cofired ceramics PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655848 SP - 1 EP - 7 CY - e-Journal of Nondestructive Testing AN - OPUS4-65584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ferrari, Bruno A1 - Fantin, Andrea A1 - Said, D. A1 - Fitch, A. N. A1 - Suárez Ocano, Patricia A1 - Mishurova, Tatiana A1 - Roveda, Ilaria A1 - Kromm, Arne A1 - Darvishi Kamachali, Reza A1 - Bruno, Giovanni A1 - Evans, Alexander A1 - Requena, G. A1 - Agudo Jácome, Leonardo A1 - Serrano Munoz, Itziar T1 - The impact of scanning strategy on cell structures in PBF-LB/M/IN718: an in situ synchrotron x-ray diffraction study N2 - In additive manufacturing, any change of the process parameters, such as scanning strategy, directly affects the cooling rates, heat accumulation, and overall thermal history of the build. Consequently, parts built with different process parameters tend to have different levels of crystallographic texture, residual stress, and dislocation density. These features can influence the properties of the material and their development during post-processing operations. In this study, IN718 prisms were built by laser powder bed fusion (PBF-LB/M) using two different scanning strategies (continuous 67° rotations around the build direction, ROT, and alternating 0°/67° scans, ALT) to provide two different as-built conditions. In situ time-resolved synchrotron diffraction was performed during a solution heat treatment at 1027 °C for 1 h. Ex situ scanning electron microscopy was used to support and complement the in situ observations. An approach to quantify the effect of elemental microsegregation at the cell walls is developed based on the deconvolution of asymmetric γ-nickel matrix peaks. Following this approach, the scanning strategies are shown to affect the as-built fraction of cell walls in the material, resulting in a difference of approximately 5 %, in weight fraction, between ROT and ALT (19 % vs. 24 %, respectively). This microsegregation was observed to be rapidly homogenized during the heating ramp, and no significant changes to the peak shape in the γ peaks occurred during the isothermal part of the heat treatment, regardless of the scanning strategy. KW - Additive manufacturing KW - Inconel 718 KW - Synchrotron x-ray diffraction KW - Heat treatment KW - Laser powder bed fusion KW - Cellular microstructure PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650958 DO - https://doi.org/10.1016/j.jmrt.2025.11.214 SN - 2238-7854 VL - 41 SP - 593 EP - 608 PB - Elsevier B.V. AN - OPUS4-65095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nadammal, Naresh A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Thiede, Tobias A1 - Kromm, Arne A1 - Seyfert, Christoph A1 - Farahbod, Lena A1 - Haberland, Christoph A1 - Schneider, Judith Ann A1 - Portella, Pedro Dolabella A1 - Bruno, Giovanni T1 - Effect of hatch length on the development of microstructure, texture and residual stresses in selective laser melted superalloy Inconel 718 N2 - In the present study, samples fabricated by varying the deposition hatch length during selective laser melting of nickel based superalloy Inconel 718 were investigated. Microstructure and texture of these samples was characterized using scanning electron microscopy, combined with electron back-scattered diffraction, and residual stress assessment, using neutron diffraction method. Textured columnar grains oriented along the sample building direction were observed in the shorter hatch length processed sample. A ten-fold increase in the hatch length reduced the texture intensity by a factor of two attributed to the formation of finer grains in the longer hatch length sample. Larger gradients of transverse residual stress in the longer hatch length sample were also observed. Along the build direction, compressive stresses in the shorter hatch length and negligible stresses for the longer hatch length specimen were observed. Changes to the temperature gradient (G) in response to the hatch length variation, influenced the G to growth rate (R) ratio and the product G × R, in agreement with the microstructures and textures formed. For the residual stress development, geometry of the part also played an important role. In summary, tailored isotropy could be induced in Inconel 718 by a careful selection of parameters during selective laser melting. KW - Additive manufacturing KW - Nickel-based superalloy KW - Microstructure and texture KW - Residual stress KW - Electron back-scattered diffraction KW - Neutron diffraction PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0264127517308018 DO - https://doi.org/10.1016/j.matdes.2017.08.049 SN - 0264-1275 VL - 134 SP - 139 EP - 150 PB - Elsevier CY - Oxford, UK AN - OPUS4-41606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Bruno, Giovanni A1 - Garcés, G. T1 - The role of reinforcement orientation on the damage evolution of AlSi12CuMgNi + 15% Al2O3 under compression N2 - Internal damage of an AlSi12CuMgNi alloy reinforced with planar random short fibres has been investigated after compression. This damage strongly influences the load partition between matrix and reinforcement. For fibres perpendicular to the applied load, breakage and interconnected cracks appear in significantly higher volume fraction than with fibres parallel to load. KW - Neutron Diffraction KW - Damage KW - Metal Matrix Composites KW - Load Partition KW - Synchrotron CT PY - 2016 DO - https://doi.org/10.1016/j.scriptamat.2016.05.023 SN - 1359-6462 VL - 122 SP - 115 EP - 118 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-36357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liens, A. A1 - Reveron, H. A1 - Douillard, T. A1 - Blanchard, N. A1 - Lughi, V. A1 - Sergo, V. A1 - Laquai, René A1 - Müller, Bernd R. A1 - Bruno, Giovanni A1 - Schomer, S. A1 - Fürderer, T. A1 - Adolfsson, E. A1 - Courtois, N. A1 - Swain, M. A1 - Chevalier, J. T1 - Phase transformation induces plasticity with negligible damage in ceria-stabilized zirconia-based ceramics N2 - Ceramics and their composites are in general brittle materials because they are predominantly made up of ionic and covalent bonds that avoid dislocation motion at room temperature. However, a remarkable ductile behavior has been observed on newly developed 11 mol.% ceria-stabilized zirconia (11Ce-TZP) composite containing fine alumina (8 vol.% Al2O3) and elongated strontium hexa-aluminate (8 vol.% SrAl12O19) grains. The as-synthesized composite also has shown full resistance to Low Temperature Degradation (LTD), relatively high strength and exceptionally high Weibull modulus, allowing its use in a broader range of biomedical applications. In this study, to deepen the understanding of plastic deformation in Ce-TZP based composites that could soon be used for manufacturing dental implants, different mechanical tests were applied on the material, followed by complete microstructural characterization. Distinct from pure Ce-TZP material or other zirconia-based ceramics developed in the past, the material here studied can be permanently strained without affecting the Young modulus, indicating that the ductile response of tested samples cannot be associated to damage occurrence. This ductility is related to the stress-induced tetragonal to monoclinic (t-m) zirconia phase transformation, analogue to Transformation-Induced Plasticity (TRIP) steels, where retained austenite is transformed to martensite. The aim of this study is to corroborate if the observed plasticity can be associated exclusively to the zirconia t-m phase transformation, or also to microcraking induced by the transformation. The t-m transformed-zones produced after bending and biaxial tests were examined by X-ray refraction and SEM/TEM coupled with Raman. The results revealed that the observed elastic-plastic behavior occurs without extensive microcracking, confirming a purely elastic-plastic behavior driven by the phase transformation (absence of damage). KW - Zirconia KW - Ceria KW - Ceramic matrix composite KW - Plasticity KW - Phase transformation KW - X-Ray Refraction PY - 2020 UR - http://www.sciencedirect.com/science/article/pii/S1359645419307177 DO - https://doi.org/10.1016/j.actamat.2019.10.046 SN - 1359-6454 VL - 183 SP - 261 EP - 273 PB - Elsevier Ltd. AN - OPUS4-49740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mehta, B. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Markötter, Henning A1 - Bruno, Giovanni A1 - Hryha, E. A1 - Nyborg, L. A1 - Virtanen, E. T1 - Microstructure, mechanical properties and fracture mechanisms in a 7017 aluminium alloy tailored for powder bed fusion – laser beam N2 - This study addressed a 7017 Al-alloy tailored for powder bed fusion – laser beam (PBF-LB) process. The alloy was prepared by mixing 3 wt% Zr and 0.5 wt% TiC powder to standard pre-alloyed 7017 grade aluminium powder. This made printing of the alloys possible avoiding solidification cracking in the bulk and achieving high relative density (99.8 %). Such advanced alloys have significantly higher Young’s modulus (>80 GPa) than conventional Al-alloys (70–75 GPa), thus making them attractive for applications requiring high stiffness. The resulting microstructure in as-printed condition was rich in particles originating from admixed powders and primary precipitates/inclusions originating from the PBF-LB process. After performing a T6-like heat treatment designed for the PBF-LB process, the microstructure changed: Zr-nanoparticles and Fe- or Mg/Zn- containing precipitates formed thus providing 75 % increase in yield strength (from 254 MPa to 444 MPa) at the cost of decreasing ductility (∼20 % to ∼9 %). In-situ tensile testing combined with SXCT, and ex-situ tensile testing combined with fracture analysis confirmed that the fracture initiation in both conditions is highly dependent on defects originated during printing. However, cracks are deflected from decohesion around Zr-containing inclusions/precipitates embedded in the Al-matrix. This deflection is seen to improve the ductility of the material. KW - Additive manufacturing KW - Powder bed fusion Laser beam KW - X-ray computed tomography KW - Strengthening mechanisms KW - Crack propagation KW - Zirconium PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568243 DO - https://doi.org/10.1016/j.matdes.2023.111602 SN - 0264-1275 VL - 226 SP - 1 EP - 14 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-56824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni 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 - CONF A1 - Bruno, Giovanni T1 - Engineering applications of neutrons at the ILL: retrospective, present, and future N2 - In this talk, the evolution of the demand for engineering applications of neutrons at the ILL in the last 10 years is presented. It is shown that small angle neutron scattering and diffraction are highly demanded by the materials science community. Further development in the field is foreseen, with the use of in-situ (furnace, tension/compression rig, humidity cells, etc.) techniques to associate to the neutron techniques. T2 - ILL 100th Scientific Council CY - Grenoble, France DA - 09.04.2019 KW - Neutron Diffraction KW - Residual Stress KW - Small Angle Neutron Scattering KW - Engineering applications KW - Institut Laue Langevin PY - 2019 AN - OPUS4-48396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Bruno, Giovanni A1 - Buffière, J.-Y. A1 - Wegener, T. A1 - Niendorf, T. A1 - Wu, T. A1 - Zhang, X. A1 - Kashaev, N. A1 - Meneghetti, G. A1 - Hrabe, Nik A1 - Madia, Mauro A1 - Werner, Tiago A1 - Hilgenberg, Kai A1 - Koukolikova, M. A1 - Prochazka, R. A1 - Dzugan, J. A1 - Möller, B. A1 - Beretta, S. A1 - Evans, Alexander A1 - Wagener, R. A1 - Schnabel, K. T1 - Damage tolerant design of additively manufactured metallic components subjected to cyclic loading: State of the art and challenges N2 - This article is an outcome of a workshop on Fatigue of Additive Manufactured Metallic Components jointly organized by the Federal Institute for Materials Research and Testing (BAM) Berlin, Germany and the National Institute of Standards and Technology (NIST) Boulder, CO, U.S.A. The aim of the workshop was a comprehensive discussion of the specific aspects of additively manufactured (AM) components in regard to failure under cyclic loading. Undoubtedly, a better understanding and the further development of approaches for damage tolerant component design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of AM parts with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and residual stresses. Based on these aspects, concepts for damage tolerant component design for AM are reviewed and critically discussed. KW - Additive manufacturing KW - Fatigue loading KW - Component assessment KW - Damage tolerance KW - Defects KW - Residual stresses PY - 2021 DO - https://doi.org/10.1016/j.pmatsci.2021.100786 SN - 0079-6425 VL - 121 PB - Elsevier CY - Amsterdam AN - OPUS4-51937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Bruno, Giovanni A1 - Hilgenberg, Kai T1 - Towards a Methodology for Component Design of Metallic AM Parts Subjected to Cyclic Loading N2 - The safe fatigue design of metallic components fabricated by additive manufacturing (AM) is still a largely unsolved problem. This is primarily due to (a) a significant inhomogeneity of the material properties across the component; (b) defects such as porosity and lack of fusion as well as pronounced surface roughness of the asuilt components; and (c) residual stresses, which are very often present in the as‐built parts and need to be removed by post‐fabrication treatments. Such morphological and microstructural features are very different than in conventionally manufactured parts and play a much bigger role in determining the fatigue life. The above problems require specific solutions with respect to the identification of the critical (failure) sites in AM fabricated components. Moreover, the generation of representative test specimens characterized by similar temperature cycles needs to be guaranteed if one wants to reproducibly identify the critical sites and establish fatigue assessment methods taking into account the effect of defects on crack initiation and early propagation. The latter requires fracture mechanics‐based approaches which, unlike common methodologies, cover the specific characteristics of so‐called short fatigue cracks. This paper provides a discussion of all these aspects with special focus on components manufactured by laser powder bed fusion (L‐PBF). It shows how to adapt existing solutions, identifies fields where there are still gaps, and discusses proposals for potential improvement of the damage tolerance design of L‐PBF components KW - L‐PBF KW - Fatigue KW - Fracture KW - Defects PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525822 DO - https://doi.org/10.3390/met11050709 VL - 11 IS - 5 SP - 709 PB - MDPI CY - Basel AN - OPUS4-52582 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stegemann, Robert A1 - Cabeza, Sandra A1 - Pelkner, Matthias A1 - Lyamkin, Viktor A1 - Pittner, Andreas A1 - Werner, Daniel A1 - Wimpory, R. A1 - Boin, M. A1 - Kreutzbruck, Marc A1 - Bruno, Giovanni T1 - Influence of the microstructure on magnetic stray fields of low-carbon steel welds N2 - This study examines the relationship between the magnetic mesostructure with the microstructure of low carbon steel tungsten inert gas welds. Optical microscopy revealed variation in the microstructure of the parent material, in the heat affected and fusion zones, correlating with distinctive changes in the local magnetic stray fields measured with high spatial resolution giant magneto resistance sensors. In the vicinity of the heat affected zone high residual stresses were found using neutron diffraction. Notably, the gradients of von Mises stress and triaxial magnetic stray field modulus follow the same tendency transverse to the weld. In contrast, micro-X-ray fluorescence characterization indicated that local changes in element composition had no independent effect on magnetic stray fields. KW - TIG-welding KW - GMR sensors KW - Magnetic stray field KW - Neutron diffraction KW - Residual stress KW - Microstructure KW - Low carbon steel PY - 2018 DO - https://doi.org/10.1007/s10921-018-0522-0 SN - 0195-9298 SN - 1573-4862 VL - 37 IS - 3 SP - 66,1 EP - 18 PB - Springer US CY - New York AN - OPUS4-45855 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Surmeneva, M. A1 - Koptyug, A. A1 - Khrapov, D. A1 - Ivanov, Yuriy A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Prymak, O. A1 - Loza, K. A1 - Epple, M. A1 - Bruno, Giovanni A1 - Surmenev, R. T1 - In situ synthesis of a binary Ti–10at% Nb alloy by electron beam melting using a mixture of elemental niobium and titanium powders N2 - This study reports the results of the preliminary assessment to fabricate Ti-10at% Nb alloy by electron beam melting (EBM®) from a blend of elemental Nb and Ti powders. The microstructure of the EBM-manufactured Ti-10at% Nb alloys is sensitive to the following factors: different sintering properties of Nb and Ti powders, powder particle properties, material viscosities at varying melt pool temperatures, β-stabilizer element content and the EBM® process parameters. Three phases were observed in as-manufactured Ti-10at% Nb alloy: μm-size Nb phase, a Nb-rich β-solid solution surrounding Nb phase, lamellar structured α-phase and β-solid solution with different distribution and volume fraction. Thus, the combination of powder particle characteristics, very short time material spends in molten condition and sluggish kinetics of mixing and diffusional process in Ti-Nb alloy results in heterogeneous microstructures depending on the local Nb content in the powder blend and the EBM® process conditions. KW - Additive manufacturing KW - Electron beam melting KW - Ti-Nb alloy KW - In situ alloying PY - 2020 DO - https://doi.org/10.1016/j.jmatprotec.2020.116646 VL - 282 SP - 116646 PB - Elsevier B.V. AN - OPUS4-50457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Léonard, Fabien A1 - Zhang, Zhen A1 - Krebs, Holger A1 - Bruno, Giovanni T1 - Structural and Morphological Quantitative 3D Characterisation of Ammonium Nitrate Prills by X-ray Computed Tomography N2 - The mixture of ammonium nitrate (AN) prills and fuel oil (FO), usually referred to as ANFO, is extensively used in the mining industry as a bulk explosive. One of the major performance predictors of ANFO mixtures is the fuel oil retention, which is itself governed by the complex pore structure of the AN prills. In this study, we present how X-ray computed tomography (XCT), and the associated advanced data processing workflow, can be used to fully characterise the structure and morphology of AN prills. We show that structural parameters such as volume fraction of the different phases and morphological parameters such as specific surface area and shape factor can be reliably extracted from the XCT data, and that there is a good agreement with the measured oil retention values. Importantly, oil retention measurements (qualifying the efficiency of ANFO as explosives) correlate well with the specific surface area determined by XCT. XCT can therefore be employed non-destructively; it can accurately evaluate and characterise porosity in ammonium nitrate prills, and even predict their efficiency. KW - ANFO KW - Explosives KW - Surface area KW - Porosity KW - XCT KW - Data processing PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-505395 DO - https://doi.org/10.3390/ma13051230 VL - 13 IS - 5 (Special Issue "Micro Non-Destructive Testing and Evaluation") SP - 1230 PB - MDPI AN - OPUS4-50539 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 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 - TY - JOUR A1 - Laquai, René A1 - Müller, Bernd R. A1 - Kasperovich, G. A1 - Requena, G. A1 - Haubrich, J. A1 - Bruno, Giovanni T1 - Classification of defect types in SLM Ti-6Al-V4 by X-ray refraction topography N2 - Porosity in additively manufactured materials, such as laser powder bed fusion Ti-Al6-V4, can play an important role in their mechanical performance. Not only the total porosity but also the shape/morphology of the individual pores need to be considered. Therefore, it is necessary to determine the distributions of different defect types (especially fusing defects and keyhole pores) and their dependence on process parameters. We show that synchrotron X-ray refraction radiography allows analysis of large samples (up to several millimeters) without compromising the detectability of submicrometer defects. Correspondingly, a classification tool is introduced that is able to quantitatively distinguish defects such as keyhole pores and binding defects with a confidence level of 94 %, even when the shape cannot be discerned because of limited spatial resolution. KW - Additive manufacturing KW - Selective laser melting KW - X-ray refraction KW - Microscopy KW - Porosity KW - X-ray computed tomography KW - BAMline KW - Synchrotron Radiation PY - 2020 DO - https://doi.org/10.1520/MPC20190080 SN - 2379-1365 VL - 9 IS - 1 SP - 82 EP - 93 PB - ASTM International CY - West Conshohocken, PA AN - OPUS4-50470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Fernández, R. A1 - Saliwan Neumann, Romeo A1 - González-Doncel, G. A1 - Bruno, Giovanni T1 - Dislocation substructures in pure aluminium after creep deformation as studied by electron backscatter diffraction N2 - In the present work, electron backscatter diffraction was used to determine the microscopic dislocation structures generated during creep (with tests interrupted at the steady state) in pure 99.8% aluminium. This material was investigated at two different stress levels, corresponding to the power-law and power-law breakdown regimes. The results show that the formation of subgrain cellular structures occurs independently of the crystallographic orientation. However, the density of these cellular structures strongly depends on the grain crystallographic orientation with respect to the tensile axis direction, with <111> grains exhibiting the highest densities at both stress levels. It is proposed that this behaviour is due to the influence of intergranular stresses, which is different in <111> and <001> grains. KW - Creep KW - Pure aluminium KW - Electron backscatter diffraction KW - Cellular structures KW - Power law and power-law breakdown PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552003 DO - https://doi.org/10.1107/S1600576722005209 SN - 0021-8898 SN - 1600-5767 VL - 55 SP - 860 EP - 869 PB - Wiley-Blackwell CY - Copenhagen AN - OPUS4-55200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Applications of X-ray refraction to non-destructive characterization of ceramics and composites N2 - X-ray refraction is analogous to visible light deflection by matter, with two main differences: 1- convex objects cause divergence (i.e., the refraction index n is smaller than 1), and 2- deflection angles are very small, from a few seconds to a few minutes of arc (i.e., n is near to 1). Trivially but 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 (light) 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, their detectability is simply limited by the wavelength of the radiation. We will thereby show the application of X-ray refraction 2D mapping (topography) and tomography to different sorts of problems in ceramic science and technology: 1) Sintering of SiC green bodies; 2) Porosity analysis in diesel particulate filter silicates; 3) fiber de-bonding in metal and polymer matrix composites; 4) micro-cracking of glass-precursor -eucryptite. We will see that the use of X-ray refraction analysis yields quantitative results, also directly usable in available models. T2 - FiMPART 2017 CY - Bordeaux, France DA - 09.07.2017 KW - Refraction radiography KW - Ceramics KW - Refraction tomography KW - Composites PY - 2017 AN - OPUS4-41040 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cooper, R. A1 - Bruno, Giovanni A1 - Shyam, A. A1 - Watkins, T. A1 - Pandey, A. A1 - Wheeler, M. T1 - Effect of microcracking on the uniaxial tensile response of beta-eucryptite ceramics: Experiments and constitutive model N2 - A constitutive model for the nonlinear or “pseudoplastic” mechanical behavior in a linear-elastic solid with thermally induced microcracks is developed and applied to experimental results. The model is termed strain dependent microcrack density approximation (SDMDA) and is an extension of the modified differential scheme that describes the slope of the stress-strain curves of microcracked solids. SDMDA allows a continuous variation in the microcrack density with tensile loading. Experimental uniaxial tensile response of β-eucryptite glass and ceramics with controlled levels of microcracking is reported. It is demonstrated that SDMDA can well describe the extent of non-linearity in the experimental uniaxial tensile response of β-eucryptite with varying levels of microcracking. The advantages of the SDMDA are discussed in regard to tensile loading. KW - Microcracking KW - β-eucryptite KW - Young's modulus KW - Modeling KW - Tensile behavior PY - 2017 DO - https://doi.org/10.1016/j.actamat.2017.06.033 SN - 1359-6454 SN - 1873-2453 VL - 135 SP - 361 EP - 371 PB - Elsevier Ltd. AN - OPUS4-40859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evans, Alexander A1 - Schröder, Jakob A1 - Pirling, T. A1 - Ulbricht, Alexander A1 - Suárez Ocaño, Patricia A1 - Bruno, Giovanni T1 - Resolving the Subsurface Residual Stress Maximum in Laser Powder Bed-Fused 316L Stainless Steel by Diffraction-Based Analysis N2 - Laser powder bed fusion (PBF-LB/M) is a metal additive manufacturing process. Due to the complex nature of the layer-wise, repeated heating and cooling cycles, it tends to generate high-magnitude residual stresses. If not correctly understood and mitigated through in- or post-process approaches, these residual stresses can be detrimental as they are often tensile at the surface. However, determining the magnitude and location of peak tensile residual stresses is not trivial as they are often located subsurface. This work focuses on determining the magnitude and location of these deleterious tensile residual stresses in a PBF-LB/316L specimen. Two diffraction-based Methods are used to reveal the relationship between the residual stresses and the underlying microstructure. On the one hand, high spatial resolution Neutron diffraction is used to determine triaxial stresses from the bulk to a depth of 0.15 mm. On the other hand, laboratory X-ray diffraction coupled with electrolytical layer removal allows the biaxial residual stress depth profile to be probed from the surface to a depth of about 0.6 mm. The results show a good agreement between the two methods. The peak residual stress is shown to be 500 MPa, which appears as a plateau between 0.08 and 0.35 mm in depth. KW - Residual stress KW - Diffraction KW - Laser Powder Bed Fusion KW - 316L KW - Additive manufacturing KW - Microstructure KW - AGIL PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652138 DO - https://doi.org/10.1007/s11837-025-07719-y SN - 1543-1851 VL - 77 IS - 12 SP - 9726 EP - 9737 PB - Springer Nature AN - OPUS4-65213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Léonard, Fabien A1 - Hasenfelder, Uta A1 - Krebs, Holger A1 - Bruno, Giovanni T1 - Assessment of shock tube systems by synchrotron X-ray computed tomography N2 - Shock tube systems are non-electric explosive fuses employed in blasting and demolition applications to trigger the detonation of explosive charges. Their working principle is based on the explosive reaction of a fine explosive powder on the tubing's inner surface, generating a shock wave traveling at a velocity of 2,100 m/s along the length of the tube, without destroying it. One of the key aspects of the manufacturing process of these shock tubes is the size and morphology of the explosive powder grains and their distribution on the inner wall of the tube, in order to propagate the shockwave efficiently and reliably. For the first time, synchrotron X-ray computed tomography has been used to characterize non-destructively the explosive powder grains, typically Al/HMX between 10 and 20 μm in size, in terms of morphology and 3D distribution but also to characterise the presence and location of defects within the shock tube walls. KW - Explosives KW - Nonel KW - Shock wave KW - Blasting KW - Energetic systems PY - 2017 UR - http://www.ndt.net/events/iCT2017/app/content/Paper/61_Leonard.pdf SP - 1 EP - 7 CY - Leuven, Belgium AN - OPUS4-39345 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 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 - Fernández, R. A1 - Bokuchava, G. A1 - Toda-Caraballo, I. A1 - Bruno, Giovanni A1 - Turchenko, V. A1 - Gorshkova, Y. A1 - González-Doncel, G. T1 - Analysis of the Combined Strengthening Effect of Solute Atoms and Precipitates on Creep of Aluminum Alloys N2 - The creep strengthening mechanisms in (age-hardenable) aluminum alloys are analyzed on the basis of a new microstructural study of powder samples, an analysis of a comprehensive revision of creep data from the literature, and a new modeling approach. A strategy based on the strength difference (SD) method to separate the contributions of solid solution atoms and precipitates to creep strengthening is proposed. The new methodology considers the combination of the two contributions avoiding the need of a threshold stress term in the creep equation. The contribution of both precipitates and solid solution is taken into account by means of the analysis of the lattice parameter variation with aging time. For this study, powders of two commercial AA2xxx alloys have been analyzed using diffraction methods. The experimental results are modeled using Lubarda's approach combined with the SD method. KW - Aluminium KW - Creep KW - Diffraction KW - Precipitation KW - Solute atoms PY - 2020 DO - https://doi.org/10.1002/adem.201901355 SN - 1438-1656 VL - 22 SP - 1901355 EP - 4 PB - Wiley-VCH Verlag AN - OPUS4-50424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruno, Giovanni A1 - Fernández, R. A1 - González-Doncel, G. A1 - Garcés, G. T1 - Towards a comprehensive understanding of creep: Microstructural dependence of the pre-exponential term in Al N2 - We show that the equation proposed by Takeuchi and Argon to explain the creep behavior of Al–Mg solid solution can be used to describe also the creep behavior of pure aluminum. In this frame, it is possible to avoid the use of the classic pre-exponential fitting parameter in the power law equation to predict the minimum creep strain rate. The effect of the fractal arrangement of dislocations, developed at the mesoscale, must be considered to fully explain the experimental data. These ideas allow improving the recently introduced SSTC model, fully describing the primary and secondary creep regimes of aluminum alloys without the need for fitting. Creep data from commercially pure Al99.8% and Al–Mg alloys tested at different temperatures and stresses are used to validate the proposed ideas. KW - Creep KW - Aluminum alloys KW - Dislocations KW - Fractal KW - Stress exponent KW - Neutron diffraction PY - 2020 DO - https://doi.org/10.1016/j.msea.2020.139036 VL - 776 SP - 139036 AN - OPUS4-50437 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Léonard, Fabien A1 - Zhang, Zhen A1 - Krebs, Holger A1 - Bruno, Giovanni T1 - Morphological characterisation of explosive powders by XCT: When grain numbers count N2 - Ammonium nitrate (AN) prills are commonly used as an ingredient in industrial explosives and in fertilisers. Conventional techniques (such as BET or mercury intrusion porosimetry) can measure the open porosity and specific surface area of AN prill, but the closed porosity is not obtainable. This work was focused on evaluating X-ray computed tomography (XCT) as a non-destructive technique for the assessment of porosity in AN prills. An advanced data processing workflow was developed so that the segmentation and quantification of the CT data could be performed on the entire 3D volume, yet allowing the measurements (e.g.; volume, area, shape factor…) to be extracted for each individual phase (prill, open porosity, closed porosity) of each individual prill, in order to obtain statistically relevant data. Clear morphological and structural differences were seen and quantified between fertiliser and explosive products. Overall, CT can provide a very wide range of parameters that are not accessible to other techniques, destructive or non-destructive, and thus offers new insights and complementary information. T2 - 10th Conference on Industrial Computed Tomography (iCT 2020) CY - Wels, Austria DA - 04.02.2020 KW - Ammonium nitrate KW - Prill KW - Non-destructive characterisation KW - Porosity KW - Specific surface area PY - 2020 UR - http://www.ndt.net/?id=25118 SN - 1435-4934 VL - 25 IS - 2 SP - 1 EP - 6 PB - NDT.net CY - Kirchwald AN - OPUS4-50348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - Diffraction-based experimental determination of Residual Stress in AM parts: A critical discussion N2 - Additive manufacturing (AM) technologies have experienced an exceedingly rapid growth, not always paralleled by the knowledge about the materials properties and performance. In particular, residual stress (RS) has been soon recognized as an issue in AM parts, so that parts are always post-heat-treated. Moreover, much effort has been spent on simulating RS, especially using finite element methods. The experimental determination of RS has thereby become increasingly important, and even simple data constitute (to date) a piece of knowledge to fill the above-mentioned gap. In particular, diffraction methods, which are basically non-destructive, offer enormous possibilities to gain knowledge on real components, since neutrons and synchrotron radiation can penetrate even heavy metals up to several millimeters (or even centimeters). Indeed, some success has been obtained, and the knowledge about the origins of the RS fields, as well as their variation as a consequence of heat or mechanical treatments, has been greatly expanded. In this talk, a few success stories will be outlined. It will be shown how the determination of RS in metallic parts (with focus on those produced by laser powder bed fusion) has even allowed showing that process parameters that were considered unimportant play a major role in the onset of stress. However, while RS is starting to be considered in the part design, deposition strategy (e.g. build plate temperature), and even in the definition of the relevant metric to assess the quality of a part, much is still to be investigated about the hypotheses underlying its experimental determination. Therefore, some aspects to be aware of, or even to date unclear will also be discussed, such as the determination of the reference unstrained samples and of the principal axes of stress. All these aspects will draw the path towards a comprehensive understanding of the process-structure-performance relationships in AM materials and parts. T2 - MSTAM 2019 CY - Bremen, Germany DA - 10.12.2019 KW - Elastic Constants KW - Residual Stress KW - Additive Manufacturing KW - Neutron Diffraction PY - 2019 AN - OPUS4-50020 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Polatidis, E. A1 - Čapek, J. A1 - Mohr, Gunther A1 - Serrano-Munoz, Itziar A1 - Bruno, Giovanni T1 - Understanding the impact of texture on the micromechanical anisotropy of laser powder bed fused Inconel 718 N2 - The manufacturability of metallic alloys using laser-based additive manufacturing methods such as laser powder bed fusion has substantially improved within the last decade. However, local melting and solidification cause hierarchically structured and crystallographically textured microstructures possessing large residual stress. Such microstructures are not only the origin of mechanical anisotropy but also pose metrological challenges for the diffraction-based residual stress determination. Here we demonstrate the influence of the build orientation and the texture on the microstructure and consequently the mechanical anisotropy of as-built Inconel 718. For this purpose, we manufactured specimens with [001]/[011]-, [001]- and [011]/[111]-type textures along their loading direction. In addition to changes in the Young’s moduli, the differences in the crystallographic textures result in variations of the yield and ultimate tensile strengths. With this in mind, we studied the anisotropy on the micromechanical scale by subjecting the specimens to tensile loads along the different texture directions during in situ neutron diffraction experiments. In this context, the response of multiple lattice planes up to a tensile strain of 10% displayed differences in the load partitioning and the residual strain accumulation for the specimen with [011]/[111]-type texture. However, the relative behavior of the specimens possessing an [001]/[011]- and [001]-type texture remained qualitatively similar. The consequences on the metrology of residual stress determination methods are discussed. KW - Laser powder bed fusion KW - Additive manufacturing KW - Electron backscatter diffraction KW - Tensile testing KW - Diffraction PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555840 DO - https://doi.org/10.1007/s10853-022-07499-9 SN - 1573-4803 VL - 2022 IS - 57 SP - 15036 EP - 15058 PB - Springer Science + Business Media B.V. CY - Dordrecht AN - OPUS4-55584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Luzin, V. A1 - Abreu Faria, G. A1 - Degener, Sebastian A1 - Polatidis, E. A1 - Čapek, J. A1 - Kromm, Arne A1 - Dovzhenko, G. A1 - Bruno, Giovanni T1 - Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts N2 - Although layer-based additive manufacturing methods such as laser powder bed fusion (PBF-LB) offer an immense geometrical freedom in design, they are typically subject to a build-up of internal stress (i.e. thermal stress) during manufacturing. As a consequence, significant residual stress (RS) is retained in the final part as a footprint of these internal stresses. Furthermore, localized melting and solidification inherently induce columnar-type grain growth accompanied by crystallographic texture. Although diffraction-based methods are commonly used to determine the RS distribution in PBF-LB parts, such features pose metrological challenges in their application. In theory, preferred grain orientation invalidates the hypothesis of isotropic material behavior underlying the common methods to determine RS. In this work, more refined methods are employed to determine RS in PBF-LB/M/IN718 prisms, based on crystallographic texture data. In fact, the employment of direction-dependent elastic constants (i.e. stress factors) for the calculation of RS results in insignificant differences from conventional approaches based on the hypothesis of isotropic mechanical properties. It can be concluded that this result is directly linked to the fact that the {311} lattice planes typically used for RS analysis in nickel-based alloys have high multiplicity and less strong texture intensities compared with other lattice planes. It is also found that the length of the laser scan vectors determines the surface RS distribution in prisms prior to their removal from the baseplate. On removal from the baseplate the surface RS considerably relaxes and/or redistributes; a combination of the geometry and the scanning strategy dictates the sub-surface RS distribution. KW - Additive manufacturing KW - Electron backscattered diffraction KW - Principal stress KW - Residual stress PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578331 DO - https://doi.org/10.1107/S1600576723004855 SN - 1600-5767 VL - 56 IS - Pt 4 SP - 1076 EP - 1090 AN - OPUS4-57833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oster, Simon A1 - Fritsch, Tobias A1 - Ulbricht, Alexander A1 - Mohr, Gunther A1 - Bruno, Giovanni A1 - Maierhofer, Christiane A1 - Altenburg, Simon T1 - On the Registration of Thermographic In Situ Monitoring Data and Computed Tomography Reference Data in the Scope of Defect Prediction in Laser Powder Bed Fusion N2 - The detection of internal irregularities is crucial for quality assessment in metal-based additive manufacturing (AM) technologies such as laser powder bed fusion (L-PBF). The utilization of in-process thermography as an in situ monitoring tool in combination with post-process X-ray micro computed tomography (XCT) as a reference technique has shown great potential for this aim. Due to the small irregularity dimensions, a precise registration of the datasets is necessary as a requirement for correlation. In this study, the registration of thermography and XCT reference datasets of a cylindric specimen containing keyhole pores is carried out for the development of a porosity prediction model. The considered datasets show variations in shape, data type and dimensionality, especially due to shrinkage and material elevation effects present in the manufactured part. Since the resulting deformations are challenging for registration, a novel preprocessing methodology is introduced that involves an adaptive volume adjustment algorithm which is based on the porosity distribution in the specimen. Thus, the implementation of a simple three-dimensional image-to-image registration is enabled. The results demonstrate the influence of the part deformation on the resulting porosity location and the importance of registration in terms of irregularity prediction. KW - Selective laser melting (SLM) KW - Laser powder bed fusion (L-PBF) KW - Additive manufacturing (AM) KW - Process monitoring KW - Infrared thermography KW - X-ray computed tomography (XCT) KW - Defect detection KW - Image registration PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549412 DO - https://doi.org/10.3390/met12060947 VL - 12 IS - 6 SP - 1 EP - 21 PB - MDPI AN - OPUS4-54941 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sprengel, Maximilian A1 - Mohr, Gunther A1 - Altenburg, Simon A1 - Evans, Alexander A1 - Serrano-Munoz, Itziar A1 - Kromm, Arne A1 - Pirling, T. A1 - Bruno, Giovanni A1 - Kannengießer, Thomas T1 - Triaxial Residual Stress in Laser Powder Bed Fused 316L: Effects of Interlayer Time and Scanning Velocity N2 - The triaxial distribution of the residual stress in laser powder bed fused austenitic steel 316L was determined by X-ray and neutron diffraction. The residual stress analysis results were linked to the thermal history of the specimens, which were manufactured with varying inter-layer-times and scanning velocities. A clear link between the in-process temperature of the specimens and the residual stress was found, based on in-situ monitoring data. KW - Stainless Steel KW - AGIL KW - Residual Stress KW - X-ray and Neutron Diffraction KW - Additive Manufacturing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542620 DO - https://doi.org/10.1002/adem.202101330 SP - 1 EP - 13 PB - Wiley-VCH GmbH AN - OPUS4-54262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ulbricht, Alexander A1 - Ávila Calderón, Luis A1 - Sommer, Konstantin A1 - Mohr, Gunther A1 - Evans, Alexander A1 - Skrotzki, Birgit A1 - Bruno, Giovanni T1 - Evolution of Creep Damage of 316L Produced by Laser Powder Bed Fusion N2 - The damage mechanisms of metallic components produced by process laser powder bed fusion differ significantly from those typically observed in conventionally manufactured variants of the same alloy. This is due to the unique microstructures of additively manufactured materials. Herein, the focus is on the study of the evolution of creep damage in stainless steel 316L specimens produced by laser powder bed fusion. X-ray computed tomography is used to unravel the influence of the process-specific microstructure from the influence of the initial void distribution on creep damage mechanisms. The void distribution of two specimens tested at 600 °C and 650 °C is analyzed before a creep test, after an interruption, and after fracture. The results indicate that the formation of damage is not connected to the initial void distribution. Instead, damage accumulation at grain boundaries resulting from intergranular cracking is observed. KW - Creep KW - Computed Tomography KW - PBF-LB/M/316L KW - Laser Powder Bed Fusion KW - Microstructure KW - AISI 316L KW - Additive Manufacturing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574127 DO - https://doi.org/10.1002/adem.202201581 SP - 1 EP - 9 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-57412 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Hentschel, M. P. A1 - Lange, A. A1 - Trappe, Volker A1 - Laquai, René A1 - Shashev, Yury A1 - Evsevleev, Sergei A1 - Bruno, Giovanni T1 - Progress survey of X-Ray refraction imaging techniques N2 - The most substantial innovations in radiographic imaging techniques of the last two decades aim at enhanced image contrast of weakly absorbing micro and nano structures by taking advantage of X-ray refraction effects occurring at outer and inner surfaces. The applications range from fibre reinforced plastics to biological tissues. These techniques comprise, among others, X-ray refraction topography, diffraction enhanced imaging, phase contrast imaging, Talbot-Lau grating interferometry, and refraction enhanced imaging. They all make use of selective beam deflections up to a few minutes of arc: the X-ray refraction effect. In contrast to diffraction, this type of interaction has a 100 % scattering cross section, as shown experimentally. Since X-ray refraction is very sensitive to the orientation of interfaces, it is additionally a tool to detect, e.g., fibre or pore orientation. If the detector resolution exceeds the size of (small) individual features, one detects the integral information (of inner surfaces) within the gauge volume. We describe the above-mentioned techniques, and show their experimental implementation in the lab and at a synchrotron source. We also show strategies for data processing and quantitative analysis. T2 - 19th World Conference on Non-Destructive Testing CY - Munich, Germany DA - 13.06.2016 KW - grating KW - topography KW - refraction KW - X-ray PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366194 SN - 978-3-940283-78-8 VL - 2016/158 SP - We.3.B.2, 1 EP - 9 AN - OPUS4-36619 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 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 - CONF A1 - Cabeza, Sandra A1 - Bruno, Giovanni A1 - Mishurova, Tatiana T1 - Characterization of multiphase metal matrix composites by means of CT and neutron diffraction N2 - The present study examines the relationship between the microstructure of multiphase metal matrix composites and their damage mechanisms. The matrix AlSi12CuMgNi was combined with 15% vol. Al₂O₃ (short fibers), and with 7% vol. Al₂O₃ + 15% vol. SiC (short fibers and whiskers, respectively). The experimental approach encompasses 3D microstructure characterization by means of computed tomography of samples (a) as-cast, (b) after heat treatment, and (c) after compression tests at room temperature. The volume fraction of different phases, their distribution, their orientation, and the presence of defects and damage are studied. The influence of the addition of SiC particles on mechanical properties of composite was investigated. Phase-specific load partition analysis for samples with fiber plane parallel to load was performed by using neutron diffraction (ND) during in-situ compression. ND results show damage in the Si phase, while Al₂O₃ short fibers carry load without damage until failure. The computed tomography observations confirm the load partition analysis. T2 - WCNDT CY - München, Germany DA - 13.06.2016 KW - thermal treatment KW - synchrotron CT KW - neutron diffraction KW - composite KW - aluminum KW - residual stress PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365499 AN - OPUS4-36549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Britzke, Ralf A1 - Bruno, Giovanni A1 - Mueller, Bernd R. A1 - Hentschel, Manfred P. T1 - Talbot- Lau interferometry with a non- binary phase grating for non-destructive testing N2 - Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect. At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems. We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes. Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries. T2 - WCNDT2016 CY - Munich, Germany DA - 13.06.2016 KW - Phase-contrast X-ray imaging KW - Talbot- Lau interferometry KW - Phase grating KW - Visibility KW - Synchrotron radiation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365987 SN - 978-3-940283-78-8 VL - BB 158 SP - Tu.3.G.2., 1 EP - 9 AN - OPUS4-36598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Cabeza, Sandra A1 - Artzt, Katia A1 - Haubrich, J. A1 - Klaus, M. A1 - Genzel, Ch. A1 - Requena, G. A1 - Bruno, Giovanni T1 - An Assessment of Subsurface Residual Stress Analysis in SLM Ti-6Al-4V N2 - Ti-6Al-4V bridges were additively fabricated by selective laser melting (SLM) under different scanning speed conditions, to compare the effect of process energy density on the residual stress state. Subsurface lattice strain characterization was conducted by means of synchrotron diffraction in energy dispersive mode. High tensile strain gradients were found at the frontal surface for samples in an as-built condition. The geometry of the samples promotes increasing strains towards the pillar of the bridges. We observed that the higher the laser energy density during fabrication, the lower the lattice strains. A relief of lattice strains takes place after heat treatment. KW - Selective laser melting KW - Additive manufacturing KW - Heat treatment KW - Ti-6Al-4V KW - Synchrotron X-ray diffraction KW - Residual stress PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395759 DO - https://doi.org/10.3390/ma10040348 SN - 1996-1944 VL - 10 IS - 4 SP - Article 348, 1 EP - 14 AN - OPUS4-39575 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Obaton, A-F. A1 - Fain, J. A1 - Djemaï, M. A1 - Meinel, Dietmar A1 - Léonard, Fabien A1 - Mahé, E. A1 - Lécuelle, B. A1 - Fouchet, J-J. A1 - Bruno, Giovanni T1 - In vivo XCT bone characterization of lattice structured implants fabricated by additive manufacturing N2 - Several cylindrical specimens and dental implants, presenting diagonal lattice structures with different cell sizes (600, 900 and 1200 µm) were additively manufactured by selective laser melting process. Then they were implanted for two months in a sheep. After removal, they were studied by Archimedes’ method as well as X-ray computed tomography in order to assess the penetration of bone into the lattice. We observed that the additive manufactured parts were geometrically conform to the theoretical specifications. However, several particles were left adhering to the surface of the lattice, thereby partly or entirely obstructing the cells. Nevertheless, bone penetration was clearly visible. We conclude that the 900 µm lattice cell size is more favourable to bone penetration than the 1200 µm lattice cell size, as the bone penetration is 84 % for 900 µm against 54 % for 1200 µm cell structures. The lower bone penetration value for the 1200 µm lattice cell could possibly be attributed to the short residence time in the sheep. Our results lead to the conclusion that lattice implants additively manufactured by selective laser melting enable better bone integration. KW - Biomedical engineering KW - Dentistry KW - Medical imaging KW - X-ray computer tomography PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418648 DO - https://doi.org/10.1016/j.heliyon.2017.e00374 SN - 2405-8440 IS - 3 SP - Article e00374, 1 EP - 21 PB - Elsevier Limited CY - 125 London Wall London, EC2Y 5AS United Kingdom AN - OPUS4-41864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Britzke, Ralf A1 - Bruno, Giovanni A1 - Müller, Bernd R. A1 - Hentschel, M. P. T1 - Talbot- Lau interferometry with a non- binary phase grating for non-destructive testing N2 - Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect. At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems. We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes. Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries. T2 - 19th World Conference on Non-Destructive Testing 2016 CY - Munich, Germany DA - 13.06.2016 KW - Talbot- Lau interferometry KW - Phase grating KW - Non-destructive testing PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-383163 SP - Tu_3_G_2, 1 EP - 9 AN - OPUS4-38316 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 - Exploring the correlation between subsurface residual stresses and manufacturing parameters in laser powder bed fused Ti-6Al-4V N2 - Subsurface residual stresses (RS) were investigated in Ti-6Al-4V cuboid samples by means of X-ray synchrotron diffraction. The samples were manufactured by laser powder bed fusion (LPBF) applying different processing parameters, not commonly considered in open literature, in order to assess their influence on RS state. While investigating the effect of process parameters used for the calculation of volumetric energy density (such as laser velocity, laser power and hatch distance), we observed that an increase of energy density led to a decrease of RS, although not to the same extent for every parameter variation. Additionally, the effect of support structure, sample roughness and LPBF machine effects potentially coming from Ar flow were studied. We observed no influence of support structure on subsurface RS while the orientation with respect to Ar flow showed to have an impact on RS.We conclude recommending monitoring such parameters to improve part reliability and reproducibility. KW - Additive manufacturing KW - Synchrotron X-ray diffraction KW - Residual stress KW - Ti-6Al-4V PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474281 DO - https://doi.org/10.3390/met9020261 SN - 2075-4701 VL - 9 IS - 2 SP - 261, 1 EP - 13 PB - MDPI AN - OPUS4-47428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Laquai, René A1 - Gouraud, F. A1 - Müller, Bernd R. A1 - Huger, M. A1 - Chotard, T. A1 - Antou, G. A1 - Bruno, Giovanni T1 - Evolution of Thermal Microcracking in Refractory ZrO2-SiO2 after Application of External Loads at High Temperatures N2 - Zirconia-based cast refractories are widely used for glass furnace applications. Since they have to withstand harsh chemical as well as thermo-mechanical environments, internal stresses and microcracking are often present in such materials under operating conditions (sometimes in excess of 1700 °C). We studied the evolution of thermal (CTE) and mechanical (Young’s modulus) properties as a function of temperature in a fused-cast refractory containing 94 wt.% of monoclinic ZrO2 and 6 wt.% of a silicate glassy phase. With the aid of X-ray refraction techniques (yielding the internal specific surface in materials), we also monitored the evolution of microcracking as a function of thermal cycles (crossing the martensitic phase transformation around 1000 °C) under externally applied stress. We found that external compressive stress leads to a strong decrease of the internal surface per unit volume, but a tensile load has a similar (though not so strong) effect. In agreement with existing literature on -eucryptite microcracked ceramics, we could explain These phenomena by microcrack closure in the load direction in the compression case, and by microcrack propagation (rather than microcrack nucleation) under tensile conditions. KW - Electro-fused zirconia KW - Microcracking KW - Synchrotron x-ray refraction radiography (SXRR) KW - Thermal expansion PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-477431 DO - https://doi.org/10.3390/ma12071017 VL - 12 IS - 7 SP - 1 EP - 15 PB - MDPI AN - OPUS4-47743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiede, Tobias A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Serrano-Munoz, Itziar A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - 3D shape analysis of powder for laser beam melting by synchrotron X-ray CT N2 - The quality of components made by laser beam melting (LBM) additive manufacturing is naturally influenced by the quality of the powder bed. A packing density <1 and porosity inside the powder particles lead to intrinsic voids in the powder bed. Since the packing density is determined by the particle size and shape distribution, the determination of these properties is of significant interest to assess the printing process. In this work, the size and shape distribution, the amount of the particle’s intrinsic porosity, as well as the packing density of micrometric powder used for LBM, have been investigated by means of synchrotron X-ray computed tomography (CT). Two different powder batches were investigated: Ti–6Al–4V produced by plasma atomization and stainless steel 316L produced by gas atomization. Plasma atomization particles were observed to be more spherical in terms of the mean anisotropy compared to particles produced by gas atomization. The two kinds of particles were comparable in size according to the equivalent diameter. The packing density was lower (i.e., the powder bed contained more voids in between particles) for the Ti–6Al–4V particles. The comparison of the tomographic results with laser diffraction, as another particle size measurement technique, proved to be in agreement. KW - Additive manufacturing KW - Laser beam melting KW - Synchrotron computed tomography KW - Powder analysis KW - Imaging PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474070 DO - https://doi.org/10.3390/qubs3010003 SN - 2412-382X VL - 3 IS - 1 SP - 3, 1 EP - 12 PB - MDPI AN - OPUS4-47407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kromm, Arne A1 - Cabeza, S. A1 - Mishurova, Tatiana A1 - Nadammal, Naresh A1 - Thiede, Tobias A1 - Bruno, Giovanni T1 - Residual Stresses in Selective Laser Melted Samples of a Nickel Based Superalloy N2 - Additive Manufacturing (AM) through the Selective Laser Melting (SLM) route offers ample scope for producing geometrically complex parts compared to the conventional subtractive manufacturing strategies. Nevertheless, the residual stresses which develop during the fabrication can limit application of the SLM components by reducing the load bearing capacity and by inducing unwanted distortion, depending on the boundary conditions specified during manufacturing. The present study aims at characterizing the residual stress states in the SLM parts using different diffraction methods. The material used is the nickel based superalloy Inconel 718. Microstructure as well as the surface and bulk residual stresses were characterized. For the residual stress analysis, X-ray, synchrotron and neutron diffraction methods were used. The measurements were performed at BAM, at the EDDI beamline of -BESSY II synchrotronand the E3 line -BER II neutron reactor- of the Helmholtz-Zentrum für Materialien und Energie (HZB) Berlin. The results reveal significant differences in the residual stress states for the different characterization techniques employed, which indicates the dependence of the residual state on the penetration depth in the sample. For the surface residual stresses, longitudinal and transverse stress components from X-ray and synchrotron agree well and the obtained values were around the yield strength of the material. Furthermore, synchrotron mapping disclosed gradients along the width and length of the sample for the longitudinal and transverse stress components. On the other hand, lower residual stresses were found in the bulk of the material measured using neutron diffraction. The longitudinal component was tensile and decreased towards the boundary of the sample. In contrast, the normal component was nearly constant and compressive in nature. The transversal component was almost negligible. The results indicate that a stress re-distribution takes place during the deposition of the consecutive layers. Further investigations are planned to study the phenomenon in detail. T2 - European Conference on Residual Stresses - ECRS10 CY - Leuven, Belgium DA - 11.09.2018 KW - Additive Manufacturing KW - Selective Laser Melting KW - Residual Stresses PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-459818 SN - 978-1-94529-189-0 SN - 978-1-94529-188-3 DO - https://doi.org/10.21741/9781945291890-41 SN - 2474-395X SN - 2474-3941 VL - 6 SP - 259 EP - 264 PB - Materials Research Forum LLC CY - Millersville, PA 17551, USA AN - OPUS4-45981 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 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 - 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 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 - Artzt, K. A1 - Mishurova, Tatiana A1 - Bauer, P.-P. A1 - Gussone, J. A1 - Barriobero-Vila, P. A1 - Evsevleev, Sergei A1 - Bruno, Giovanni A1 - Requena, G. A1 - Haubrich, J. T1 - Pandora’s Box–Influence of Contour Parameters on Roughness and Subsurface Residual Stresses in Laser Powder Bed Fusion of Ti-6Al-4V N2 - The contour scan strategies in laser powder bed fusion (LPBF) of Ti-6Al-4V were studied at the coupon level. These scan strategies determined the surface qualities and subsurface residual stresses. The correlations to these properties were identified for an optimization of the LPBF processing. The surface roughness and the residual stresses in build direction were linked: combining high laser power and high scan velocities with at least two contour lines substantially reduced the surface roughness, expressed by the arithmetic mean height, from values as high as 30 μm to 13 μm, while the residual stresses rose from ~340 to about 800 MPa. At this stress level, manufactured rocket fuel injector components evidenced macroscopic cracking. A scan strategy completing the contour region at 100 W and 1050 mm/s is recommended as a compromise between residual stresses (625 MPa) and surface quality (14.2 μm). The LPBF builds were monitored with an in-line twin-photodiode-based melt pool monitoring (MPM) system, which revealed a correlation between the intensity quotient I2/I1, the surface roughness, and the residual stresses. Thus, this MPM system can provide a predictive estimate of the surface quality of the samples and resulting residual stresses in the material generated during LPBF. KW - Additive manufacturing KW - Ti-6Al-4V KW - Contour scan strategy KW - Surface roughness KW - Melt pool monitoring KW - Residual stress KW - Synchrotron X-ray diffraction PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510585 DO - https://doi.org/10.3390/ma13153348 VL - 13 IS - 15 SP - 3348 AN - OPUS4-51058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Sydow, B. A1 - Thiede, Tobias A1 - Sizova, I. A1 - Ulbricht, Alexander A1 - Bambach, M. A1 - Bruno, Giovanni T1 - Residual Stress and Microstructure of a Ti-6Al-4V Wire Arc Additive Manufacturing Hybrid Demonstrator N2 - Wire Arc Additive Manufacturing (WAAM) features high deposition rates and, thus, allows production of large components that are relevant for aerospace applications. However, a lot of aerospace parts are currently produced by forging or machining alone to ensure fast production and to obtain good mechanical properties; the use of these conventional process routes causes high tooling and material costs. A hybrid approach (a combination of forging and WAAM) allows making production more efficient. In this fashion, further structural or functional features can be built in any direction without using additional tools for every part. By using a combination of forging basic geometries with one tool set and adding the functional features by means of WAAM, the tool costs and material waste can be reduced compared to either completely forged or machined parts. One of the factors influencing the structural integrity of additively manufactured parts are (high) residual stresses, generated during the build process. In this study, the triaxial residual stress profiles in a hybrid WAAM part are reported, as determined by neutron diffraction. The analysis is complemented by microstructural investigations, showing a gradient of microstructure (shape and size of grains) along the part height. The highest residual stresses were found in the transition Zone (between WAAM and forged part). The total stress range showed to be lower than expected for WAAM components. This could be explained by the thermal history of the component. KW - Additive manufacturing KW - Neutron diffraction KW - Residual stress KW - Hybrid manufacturing KW - WAAM KW - Ti-6Al-4V PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508245 DO - https://doi.org/10.3390/met10060701 VL - 10 IS - 6 SP - 701 PB - MDPI AN - OPUS4-50824 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Laquai, René A1 - Müller, Bernd R. A1 - Schneider, J. A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Using SXRR to Probe the Nature of Discontinuities in SLM Additive Manufactured Inconel 718 Specimens N2 - The utilization of additive manufacturing (AM) to fabricate robust structural components relies on understanding the nature of internal anomalies or discontinuities, which can compromise the structural integrity. While some discontinuities in AM microstructures stem from similar mechanisms as observed in more traditional processes such as casting, others are unique to the AM process. Discontinuities in AM are challenging to detect, due to their submicron size and orientation dependency. Toward the goal of improving structural integrity, minimizing discontinuities in an AM build requires an understanding of the mechanisms of formation to mitigate their occurrence. This study utilizes various techniques to evaluate the shape, size, nature and distribution of discontinuities in AM Inconel 718, in a non-hot isostatic pressed (HIPed) as-built, non-HIPed and direct age, and HIPed with two step age samples. Non-destructive synchrotron radiation refraction and transmission radiography (SXRR) provides additional information beyond that obtained with destructive optical microscopy. SXRR was able to distinguish between voids, cracks and lack of melt in, due to its sensitivity to the orientation of the discontinuity. KW - Additive manufacturing KW - X-ray refraction radiography KW - INCONEL 718 KW - Selective laser melting PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509836 DO - https://doi.org/10.1007/s11661-020-05847-5 SN - 1543-1940 VL - 51 IS - 8 SP - 4146 EP - 4157 PB - Springer AN - OPUS4-50983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishurova, Tatiana A1 - Artzt, K. A1 - Haubrich, J. A1 - Evsevleev, Sergei A1 - Evans, Alexander A1 - Meixner, M. A1 - Serrano-Munoz, Itziar A1 - Sevostianov, I. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Connecting Diffraction-Based Strain with Macroscopic Stresses in Laser Powder Bed Fused Ti-6Al-4V N2 - The laser powder bed fusion (LPBF) production process often results in large residual stress (RS) in the parts. Nondestructive techniques to determine RS are badly needed. However, a reliable quantification of macro-RS (i.e., stress at the component level) by means of diffraction-based techniques is still a great challenge, because the link between diffraction-based strain and macro-RS is not trivial. In this study, we experimentally determine (by means of in-situ synchrotron radiation diffraction) this link for LPBF Ti-6Al-4V. We compare our results with commonly used models to determine the so-called diffraction elastic constants (DECs). We show that LPBF materials possess different DECs than wrought alloys, simply because their microstructural and mechanical properties are different. We also show that the existing models can be used to calculate DECs only if high accuracy of the RS values is not required. If the peculiarities of the microstructure have to be taken into account (as is the case of additively manufactured materials), a radically new approach is desirable. KW - Tiatanium KW - Synchrotron X-ray diffraction KW - Macroscopic stress KW - Laser powder bed fusion KW - Texture KW - Diffraction elastic constants PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506483 DO - https://doi.org/10.1007/s11661-020-05711-6 VL - 51 IS - 6 SP - 3194 EP - 3204 PB - Springer AN - OPUS4-50648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Evsevleev, Sergei A1 - Sevostianov, I. A1 - Mishurova, Tatiana A1 - Hofmann, M. A1 - Garcés, G. A1 - Bruno, Giovanni T1 - Explaining Deviatoric Residual Stresses in Aluminum Matrix Composites with Complex Microstructure N2 - The residual stresses in multiphase metal Matrix composites with both random planar-oriented short fibers and particles were studied by neutron diffraction 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 observed that randomly oriented phases possess non-hydrostatic residual stress. 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. KW - Metal matrix composite KW - Residual stress KW - Deviatoric KW - Micromechanics PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506472 DO - https://doi.org/10.1007/s11661-020-05697-1 VL - 51 IS - 6 SP - 3104 EP - 3113 PB - Springer AN - OPUS4-50647 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritsch, Tobias A1 - Sprengel, Maximilian A1 - Evans, Alexander A1 - Farahbod-Sternahl, L. A1 - Saliwan Neumann, Romeo A1 - Hofmann, M. A1 - Bruno, Giovanni T1 - On the determination of residual stresses in additively manufactured lattice structures N2 - The determination of residual stresses becomes more complicated with increasing complexity of the structures investigated. Additive manufacturing techniques generally allow the production of ‘lattice structures’ without any additional manufacturing step. These lattice structures consist of thin struts and are thus susceptible to internal stress-induced distortion and even cracks. In most cases, internal stresses remain locked in the structures as residual stress. The determination of the residual stress in lattice structures through nondestructive neutron diffraction is described in this work. It is shown how two difficulties can be overcome: (a) the correct alignment of the lattice structures within the neutron beam and (b) the correct determination of the residual stress field in a representative part of the structure. The magnitude and the direction of residual stress are discussed. The residual stress in the strut was found to be uniaxial and to follow the orientation of the strut, while the residual stress in the knots was more hydrostatic. Additionally, it is shown that strain measurements in at least seven independent directions are necessary for the estimation of the principal stress directions. The measurement directions should be chosen according to the sample geometry and an informed choice on the possible strain field. If the most prominent direction is not measured, the error in the calculated stress magnitude increases considerably. KW - Additive manufacturing KW - Laser powder bed fusion KW - Residual stress KW - Principal stress components KW - Neutron diffraction KW - Lattice structures PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520663 DO - https://doi.org/10.1107/S1600576720015344 SN - 1600-5767 VL - 54 SP - 228 EP - 236 AN - OPUS4-52066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Trofimov, Anton A1 - Apel, D. A1 - Ulbricht, Alexander A1 - Kromm, Arne A1 - Hesse, René A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - On the interplay of microstructure and residual stress in LPBF IN718 N2 - The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90° XY-scan, and 67° Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the nearsurface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen Dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuß model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kröner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys. KW - L-PBF IN718 material KW - Effect of scanning strategies KW - Near-surface X-ray diffraction KW - Residual stress in AM KW - Distortion upon baseplate removal PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519460 DO - https://doi.org/10.1007/s10853-020-05553-y SN - 0022-2461 VL - 56 IS - 9 SP - 5845 EP - 5867 PB - Springer AN - OPUS4-51946 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 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 - Serrano-Munoz, Itziar A1 - Ulbricht, Alexander A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Kromm, Arne A1 - Hofmann, M. A1 - Wimpory, R. C. A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Scanning Manufacturing Parameters Determining the Residual Stress State in LPBF IN718 Small Parts N2 - The influence of scan strategy on the residual stress (RS) state of an as-built IN718 alloy produced by means of laser powder bed fusion (LPBF) is investigated. Two scan vector rotations (90°-alternation and 67°-rotation), each produced following two different scan vector lengths (long and short), are used to manufacture four rectangular prisms. Neutron diffraction (ND) and laboratory X-ray diffraction (XRD) techniques are used to map the bulk and surface RS state, respectively. The distortion induced upon removal from the baseplate is measured via profilometry. XRD measurements show that the two long scan vector strategies lead to higher RS when compared with the equivalent short scan vector strategies. Also, the 67°-rotation strategies generate lower RS than their 90°-alternation counterparts. Due to the lack of reliable stress-free d0 references, the ND results are analyzed using von Mises stress. In general, ND results show significant RS spatial non-uniformity. A comparison between ND and distortion results indicates that the RS component parallel to the building direction (Z-axis) has a predominant role in the Z-displacement. The use of a stress balance scheme allows to discuss the d0 variability along the length of the specimens, as well as examine the absolute RS state. KW - As-built LPBF IN718 alloy KW - Scan strategy influence KW - Neutron diffraction KW - Residual stress state KW - Stress balance condition KW - Distortion PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526360 DO - https://doi.org/10.1002/adem.202100158 VL - 23 IS - 7 SP - 158 PB - Wiley AN - OPUS4-52636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupsch, Andreas A1 - Laquai, René A1 - Müller, Bernd R. A1 - Paciornik, S. A1 - Horvath, J. A1 - Tushtev, K. A1 - Rezwan, K. A1 - Bruno, Giovanni T1 - Evolution of Damage in All-Oxide Ceramic Matrix Composite After Cyclic Loading N2 - While structural ceramics usually display a brittle mechanical behavior, their composites may show nonlinearities, mostly due to microcracking. Herein, the stiffness evolution of a sandwich-like laminate of an Al2O3 15%vol. ZrO2 matrix reinforced with Nextel 610 fibers is studied as a function of number of cycles N in tension. The stiffness of the composite degrades with increasing N, indicating microcracking. However, synchrotron X-ray refraction radiography shows that the internal specific surface of such cracks varies differently. A modeling strategy is developed for the calculation of the equivalent stiffness of mixtures (first the matrix and then the sandwich), based on the Voigt and Reuß schemes. The Bruno–Kachanov model is then used to estimate the initial microcrack density in the matrix (due to the thermal expansion mismatch) and the amount of microcracking increase upon cyclic loading. The stiffness in the composite degrades dramatically already after 20 000 cycles but then remains nearly constant. The combination of mechanical testing, quantitative imaging analysis, and modeling provides insights into the damage mechanisms acting: microcrack propagation is more active than microcrack initiation upon cyclic loading, but the second also occurs. This scenario is similar but not equal to previous results on porous and microcracked ceramics. KW - Ceramic matrix composites KW - Homogenization schemes KW - Microcracking KW - Nonlinear behavior KW - Synchrotron X-ray refraction radiography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534541 DO - https://doi.org/10.1002/adem.202100763 SN - 1527-2648 SN - 1438-1656 VL - 24 IS - 6 SP - 2100763 -1 EP - 2100763 -13 PB - VCH GmbH CY - Weinheim AN - OPUS4-53454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauzon, C. A1 - Mishurova, Tatiana A1 - Evsevleev, Sergei A1 - Dubiez-Le Goff, S. A1 - Murugesan, S. A1 - Bruno, Giovanni A1 - Hryha, E. T1 - Residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion as a function of process atmosphere and component design N2 - The influence of the process gas, laser scan speed, and sample thickness on the build-up of residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion was studied. Pure argon and helium, as well as a mixture of those (30% helium), were employed to establish process atmospheres with a low residual Oxygen content of 100 ppm O2. The results highlight that the subsurface residual stresses measured by X-ray diffraction were significantly lower in the thin samples (220 MPa) than in the cuboid samples (645 MPa). This difference was attributed to the shorter laser vector length, resulting in heat accumulation and thus in-situ stress relief. The addition of helium to the process gas did not introduce additional subsurface residual stresses in the simple geometries, even for the increased scanning speed. Finally, larger deflection was found in the cantilever built under helium (after removal from the baseplate), than in those produced under argon and an argon-helium mixture. This result demonstrates that complex designs involving large scanned areas could be subjected to higher residual stress when manufactured under helium due to the gas’s high thermal conductivity, heat capacity, and thermal diffusivity. KW - Additive manufacturing KW - Ti-6Al-4V KW - Residual stress KW - Process atmosphere KW - Helium PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534209 DO - https://doi.org/10.1016/j.addma.2021.102340 VL - 47 SP - 2340 PB - Elsevier B.V. AN - OPUS4-53420 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 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 - Serrano-Munoz, Itziar A1 - Evans, Alexander A1 - Mishurova, Tatiana A1 - Sprengel, Maximilian A1 - Pirling, T. A1 - Kromm, Arne A1 - Bruno, Giovanni T1 - The importance of subsurface residual stress in laser powder bed fusion IN718 N2 - The residual stress (RS) in laser powder bed fusion (LPBF) IN718 alloy samples produced using a 67°-rotation scan strategy is investigated via laboratory X-ray diffraction (XRD) and neutron diffraction (ND). The location dependence of the strain-free (d₀) lattice spacing in ND is evaluated using a grid array of coupons extracted from the far-edge of the investigated specimen. No compositional spatial variation is observed in the grid array. The calculated RS fields show considerable non-uniformity, significant stress gradients in the region from 0.6 to 2 mm below the surface, as well as subsurface maxima that cannot be accounted for via XRD. It is concluded that failure to determine such maxima would hamper a quantitative determination of RS fields by means of the stress balance method. KW - Laser powder bed fusion KW - Neutron and X-ray diffraction KW - Residual stress analysis KW - Strain-free lattice references KW - Stress balance PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-532707 DO - https://doi.org/10.1002/adem.202100895 SN - 1615-7508 SN - 1527-2648 VL - 24 IS - 6 SP - 1 EP - 7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-53270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silvestroni, L. A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Ulbricht, Alexander A1 - Wieder, Frank A1 - Fritsch, Tobias A1 - Sciti, D. A1 - Bruno, Giovanni T1 - Determination of short carbon fiber orientation in zirconium diboride ceramic matrix composites N2 - In fiber-reinforced components, the fiber alignment and orientation have paramount influence on the thermomechanical properties of the resulting composite, for both short and continuous fiber. Here we present the case of an ultra-refractory matrix intended for extreme environment applications, ZrB2, reinforced with 20 vol% and 50 vol% short carbon fibers. In both cases, fibers tend to align perpendicular to the uniaxial pressure applied during shaping and sintering of a pellet, although the fiber tilt across the pellet thickness is difficult to determine. Moreover, for high volume fractions of reinforcement, the spatial distribution of the fibers is heterogeneous and tends to have domains of preferential orientations. We compare the information on the fiber distribution as collected by scanning electron microscopy images, X-ray computed tomography and synchrotron X-ray refraction radiography (SXRR). The three techniques prove to be complementary. Importantly, we demonstrate that SXRR yields the most statistically significant information due to the largest field of view, yet with a sensitivity down to the nanometer, and that can be successfully applied also to heavy matrix materials, such as zirconium boride. KW - Ceramic matrix composites KW - Synchrotron X-ray refraction radiography KW - X-ray computed tomography KW - Scanning electron microscopy KW - High-temperature ceramics PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597712 DO - https://doi.org/10.1016/j.jeurceramsoc.2024.02.048 SN - 0955-2219 VL - 44 IS - 8 SP - 4853 EP - 4862 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-59771 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Fritsch, Tobias A1 - Luzin, Vladimir A1 - Ferrari, Bruno A1 - Simón-Muzás, Juan A1 - Evans, Alexander A1 - Bruno, Giovanni T1 - Impact of scan strategy on principal stresses in laser powder bed fusion N2 - Additive manufacturing techniques, such as laser powder bed fusion (PBF-LB), are well known for their exceptional freedom in part design. However, these techniques are also characterized by the development of large thermal gradients during production and thus residual stress (RS) formation in produced parts. In this context, neutron diffraction enables the non-destructive characterization of the bulk RS distribution. By control of the thermal gradients in the powder-bed plane by scan strategy variation we study the impact of in-process scan strategy variations on the microstructure and the three-dimensional distribution of RS. Microstructural analysis by means of electron backscatter diffraction reveals sharp microstructure transitions at the interfaces ranging from 100-200 µm. The components of the RS tensor are determined by means of neutron diffraction and the principal stress directions and magnitudes are determined by eigenvalue decomposition. We find that the distribution of RS in the powder-bed plane corresponds to the underlying scan strategy. When the alternating scan vectors align with the x- and y sample coordinate axes, the principal stress directions co-align. In the present geometry, nearly transverse isotropic stress states develop when the scan vectors are either aligned 45° between x and y or continuously rotated by 67° between each layer. KW - Additive Manufacturing KW - Laser Powder Bed Fusion KW - Electron Backscatter Diffraction KW - Neutron Diffraction KW - Residual Stress KW - Principal Stress PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607910 DO - https://doi.org/10.1016/j.matdes.2024.113171 SN - 0264-1275 VL - 244 SP - 1 EP - 10 PB - Elsevier Ltd. AN - OPUS4-60791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lapenna, Michela A1 - Tsamos, Athanasios A1 - Faglioni, Francesco A1 - Fioresi, Rita A1 - Zanchetta, Ferdinando A1 - Bruno, Giovanni T1 - Geometric deep learning for enhanced quantitative analysis of microstructures in X-ray computed tomography data N2 - Quantitative microstructural analysis of XCT 3D images is key for quality assurance of materials and components. In this paper we implement a Graph Convolutional Neural Network (GCNN) architecture to segment a complex Al-Si Metal Matrix composite XCT volume (3D image). We train the model on a synthetic dataset and we assess its performance on both synthetic and experimental, manually-labeled, datasets. Our simple GCNN shows a comparable performance, measured via the Dice score, to more standard machine learning methods, but uses a greatly reduced number of parameters (less than 1/10 of parameters), features low training time, and needs little hardware resources. Our GCNN thus achieves a cost-effective reliable segmentation. KW - Geometric deep learning KW - Segmentation KW - Microstructure KW - X-ray computed tomography KW - Al–Si metal matrix composites PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602517 DO - https://doi.org/10.1007/s42452-024-05985-0 SN - 3004-9261 VL - 6 IS - 6 SP - 1 EP - 9 AN - OPUS4-60251 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mack, D. E. A1 - Laquai, René A1 - Müller, Bernd R. A1 - Helle, O. A1 - Sebold, D. A1 - Vaßen, R. A1 - Bruno, Giovanni T1 - Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing N2 - Degradation of thermal barrier coatings (TBCs) in gas‐turbine engines due to calcium–magnesium–aluminosilicate (CMAS) glassy deposits from various sources has been a persistent issue since many years. In this study, state of the art electron microscopy was correlated with X‐ray refraction techniques to elucidate the intrusion of CMAS into the porous structure of atmospheric plasma sprayed (APS) TBCs and the formation and growth of cracks under thermal cycling in a burner rig. Results indicate that the sparse nature of the infiltration as well as kinetics in the burner rig are majorly influenced by the wetting behavior of the CMAS. Despite the obvious attack of CMAS on grain boundaries, the interaction of yttria‐stabilized zirconia (YSZ) with intruded CMAS has no immediate impact on structure and density of internal surfaces. At a later stage the formation of horizontal cracks is observed in a wider zone of the TBC layer. KW - Characterization KW - CMAS KW - Synchrotron X‐ray refraction radiography KW - Thermal barrier coatings PY - 2019 DO - https://doi.org/10.1111/jace.16465 SN - 0002-7820 SN - 1551-2916 VL - 102 IS - 10 SP - 6163 EP - 6175 PB - Wiley CY - Oxford AN - OPUS4-47804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni 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 T1 - Avoid living dangerously: non-destructive characterization of AM parts from powder to end-of-life N2 - The freeform and the revolutionary design possibilities offered by additive manufacturing have skyrocketed the amount of optimization studies in the realm of engineering, and metallic additive manufactured parts are becoming a reality in industry. Not surprisingly, this has not been paralleled by a similar enthusiastic wave in the realm of materials science, and still very little is known about AM materials properties. This has the consequence that, typically, conventional materials properties are still used in design and even in simulations. lt is necessary to dig a lot deeper than at present, in order to understand these new materials classes, and in particular their microstructure and their intemal stresses, largely different from their cast or wrought companions. T2 - ISAM Konferenz 2019 CY - Dresden, Germany DA - 29.01.2019 KW - Computed Tomography KW - Microstructure KW - Metals KW - Additive Manufacturing PY - 2019 AN - OPUS4-47331 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Bernd R. A1 - Cooper, R.C. A1 - Lange, Axel A1 - Kupsch, Andreas A1 - Wheeler, M. A1 - Hentschel, Manfred P. A1 - Staude, Andreas A1 - Pandey, A. A1 - Shyam, A. A1 - Bruno, Giovanni T1 - Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening N2 - In order to investigate their microcracking behaviour, the microstructures of several β-eucryptite ceramics, obtained from glass precursor and cerammed to yield different grain sizes and microcrack densities, were characterized by laboratory and synchrotron x-ray refraction and tomography. Results were compared with those obtained from scanning electron microscopy (SEM). In SEM images, the characterized materials appeared fully dense but computed tomography showed the presence of pore clusters. Uniaxial tensile testing was performed on specimens while strain maps were recorded and analyzed by Digital Image Correlation (DIC). X-ray refraction techniques were applied on specimens before and after tensile testing to measure the amount of the internal specific surface (i.e., area per unit volume). X-ray refraction revealed that (a) the small grain size (SGS) material contained a large specific surface, originating from the grain boundaries and the interfaces of TiO2 precipitates; (b) the medium (MGS) and large grain size (LGS) materials possessed higher amounts of specific surface compared to SGS material due to microcracks, which decreased after tensile loading; (c) the precursor glass had negligible internal surface. The unexpected decrease in the internal surface of MGS and LGS after tensile testing is explained by the presence of compressive regions in the DIC strain maps and further by theoretical arguments. It is suggested that while some microcracks merge via propagation, more close mechanically, thereby explaining the observed X-ray refraction results. The mechanisms proposed would allow the development of a strain hardening route in ceramics. KW - Beta-eucryptite KW - Microcracked ceramics KW - X-ray refraction KW - Tensile load KW - Strain hardening KW - Synchrotron KW - BAMline KW - Computed Tomography KW - CT PY - 2018 UR - http://www.sciencedirect.com/science/article/pii/S1359645417308881 DO - https://doi.org/10.1016/j.actamat.2017.10.030 SN - 1359-6454 SN - 1873-2453 VL - 144 IS - Supplement C SP - 627 EP - 641 PB - Elsevier B.V. AN - OPUS4-43024 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reveron, H. A1 - Serrano-Munoz, Itziar A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Chevalier, J. A1 - Bruno, Giovanni T1 - Transformation-induced plasticity in zirconia during tensile loading: A combined microscopy and synchrotron X-ray refraction study N2 - The stress-induced tetragonal to monoclinic (t-m) zirconia phase transformation can provide a certain degree of plasticity to Ceria-stabilized (Ce-TZP) zirconia-based composites. Characterizing and monitoring this phase transition on a millimeter-size range, within the bulk and in-situ remains a challenge. In this work, the mechanical behavior of Ce-TZP based composite was studied in tension, combining microscopy and synchrotron Xray refraction techniques. In contrast with microscopy methods, which only provide surface information, X-ray refraction radiography (SXRR) allowed the visualization of all the transformation bands, over the entire length and thickness of tested specimens, opening up new avenues for in-situ stress-induced t-m transformation studies. KW - Zirconia KW - Ceria KW - Composite KW - Phase transformation KW - Plasticity KW - Synchrotron X-ray refraction PY - 2024 DO - https://doi.org/10.1016/j.matlet.2024.136445 SN - 0167-577X SN - 1873-4979 VL - 366 SP - 1 EP - 4 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-59977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Léonard, Fabien A1 - Zhang, Zhen A1 - Malow, Marcus A1 - Bruno, Giovanni T1 - 3D characterisation of ammonium nitrate powders by X-ray computed tomography N2 - The mixture of ammonium nitrate (AN) prills and fuel oil (FO), usually called ANFO, is extensively used in the mining industry as a bulk industrial explosive. One of the major performance predictors of ANFO mixtures is the fuel oil retention, which is itself governed by the porosity of the AN prills. Standardised tests routinely used to assess oil retention face several important limitations; the first being the difficulty to cover the wide range of porosity contents and morphologies from different types of ammonium nitrate prills; the second being the inability to evaluate the closed porosity, which is an important factor regarding the sensitivity of the explosive to detonation. In this study, we present how X-ray computed tomography (XCT), and the associated advanced data processing workflow, can be used to fully characterise the structure and morphology of AN prills. We show that structural parameters such as volume fraction of the different phases and morphological parameters such as specific surface area and shape factor can be reliably extracted from the XCT data, and that there is a good agreement with the measured oil retention values. XCT can therefore be employed to non-destructively and accurately evaluate and characterise porosity in ammonium nitrate prills. T2 - 23rd Seminar on New Trends in Research of Energetic Materials CY - Meeting was canceled DA - 01.04.2020 KW - Ammonium nitrate KW - Prill KW - Non-destructive characterisation KW - Porosity KW - Specific surface area PY - 2020 SP - 163 EP - 171 AN - OPUS4-51272 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 - CONF A1 - Mishurova, Tatiana A1 - Artzt, Katia A1 - Haubrich, Jan A1 - Bruno, Giovanni A1 - Requena, Guillermo T1 - An assessment of subsurface residual stress in Selective Laser Melted Ti-6Al-4V parts N2 - In the present study, Ti-6Al-4V bridge-like specimens were manufactured additively by selective laser melting (SLM) under different laser scanning speed conditions in order to compare the effect of process energy density on the residual stress state. Subsurface residual stress analysis was conducted by means of synchrotron diffraction in energy dispersive mode for three conditions: as-built on base plate, released from base plate, and after heat treatment on the base plate. The quantitative residual stress characterization shows a correlation with the qualitative bridge curvature method. Computed tomography (CT) was carried out to ensure that no stress relief took place owing to the presence of porosity. CT allows obtaining spatial and size pores distribution which helps in optimization of the SLM process. High tensile residual stresses were found at the lateral surface for samples in the as-built conditions. We observed that higher laser energy density during fabrication leads to lower residual stresses. Samples in released condition showed redistribution of the stresses due to distortion. A method for the calculation of the stress associated to distortion of the parts after cutting from base plate is proposed. The distortion measurements were used as input for FEM simulations. T2 - Symposium Zerstörungsfreie Materialcharakterisierung. Charakterisierung additiv gefertigter Komponenten CY - Berlin, Germany DA - 28.11.2017 KW - Additive manufacturing KW - Selective laser melting KW - Residual stress KW - Synchrotron X-ray diffraction PY - 2017 AN - OPUS4-43214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -