TY - JOUR A1 - Isaac, Augusta A1 - Serrano‐Munoz, Itziar A1 - Kostka, Aleksander A1 - Widjaja, Martinus Putra A1 - González‐Doncel, Gaspar A1 - Bruno, Giovanni A1 - Fernández, Ricardo T1 - Subgrain and Cavity Development during Creep of Al‐3.85%Mg N2 - It is classically considered that the creep mechanisms for type M (e.g., pure Al) and type A alloys (e.g., Al–Mg alloys) are different. In previous studies, it is predicated that fractal dislocation structures build up during creep can unify the creep behavior of pure Al and Al–Mg alloys. So far, good agreement between model and experimental data for pure Al is obtained. In this work, an Al‐3.85%Mg material crept at different strain levels (6%, 12%, 24%, and 35%) is analyzed by means of electron channelling contrast imaging. The formation of subgrains is observed at very large deformations (35%). Further examinations at 35% deformation, using electron backscatter diffraction, indicate that the subgrains and cavities tend to localize at regions where high intergranular stress mismatch is expected to occur. Laboratory X‐ray computed tomography is used to analyze the evolution of cavities between 12% and 24% stages, indicating that the fractal dimension of the cavities smaller than 100 μm varies with creep strain, as a reflection of the evolution of dislocation distribution. It is explained how the present data feed the model of the creep behavior of Al‐3.85%Mg. KW - Al–Mg alloys KW - Creep KW - Dislocations KW - Fractal KW - Intergranular residual stress KW - Subgrains PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645905 DO - https://doi.org/10.1002/adem.202500263 SN - 1438-1656 SP - 1 EP - 10 PB - Wiley VHC-Verlag AN - OPUS4-64590 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pohl, P. A1 - Kümmel, F. A1 - Schunk, C. A1 - Serrano-Munoz, Itziar A1 - Markötter, Henning A1 - Göken, M. A1 - Höppel, H. W. T1 - About the Role of Interfaces on the Fatigue Crack Propagation in Laminated Metallic Composites N2 - The influence of gradients in hardness and elastic properties at interfaces of dissimilar materials in laminated metallic composites (LMCs) on fatigue crack propagation is investigated experimentally for three different LMC systems: Al/Al-LMCs with dissimilar yield stress and Al/Steel-LMCs as well as Al/Ti/Steel-LMCs with dissimilar yield stress and Young’s modulus, respectively. The damage tolerant fatigue behavior in Al/Al-LMCs with an alternating layer structure is enhanced significantly compared to constituent monolithic materials. The prevalent toughening mechanisms at the interfaces are identified by microscopical methods and synchrotron X-ray computed tomography. For the soft/hard transition, crack deflection mechanisms at the vicinity of the interface are observed, whereas crack bifurcation mechanisms can be seen for the hard/soft transition. The crack propagation in Al/Steel-LMCs was studied conducting in-situ scanning electron microscope (SEM) experiments in the respective low cycle fatigue (LCF) and high cycle fatigue (HCF) regimes of the laminate. The enhanced resistance against crack propagation in the LCF regime is attributed to the prevalent stress redistribution, crack deflection, and crack bridging mechanisms. The fatigue properties of different Al/Ti/Steel-LMC systems show the potential of LMCs in terms of an appropriate selection of constituents in combination with an optimized architecture. The results are also discussed under the aspect of tailored lightweight applications subjected to cyclic loading. KW - Laminated metallic composites KW - Toughening mechanisms KW - Interfaces KW - Fatigue crack propagation KW - Fatigue crack growth PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-526531 DO - https://doi.org/10.3390/ma14102564 VL - 14 IS - 10 SP - 2564 PB - MDPI AN - OPUS4-52653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Roveda, Ilaria A1 - Serrano-Munoz, Itziar A1 - Mishurova, Tatiana A1 - Madia, Mauro A1 - Pirling, T. A1 - Evans, Alexander A1 - Klaus, M. A1 - Haubrich, J. A1 - Requena, G. A1 - Bruno, Giovanni T1 - Influence of a 265 °C heat treatment on the residual stress state of a PBF-LB/M AlSi10Mg alloy N2 - Laser Powder Bed Fusion (PBF-LB/M) additive manufacturing (AM) induces high magnitude residual stress (RS) in structures due to the extremely heterogeneous cooling and heating rates. As the RS can be deleterious to the fatigue resistance of engineering components, great efforts are focused on understanding their generation and evolution after post-process heat treatments. In this study, one of the few of its kind, the RS relaxation induced in an as-built PBF-LB/M AlSi10Mg material by a low-temperature heat treatment (265 °C for 1 h) is studied by means of X-ray and neutron diffraction. Since the specimens are manufactured using a baseplate heated up to 200 °C, low RS are found in the as-built condition. After heat treatment a redistribution of the RS is observed, while their magnitude remains constant. It is proposed that the redistribution is induced by a repartition of stresses between the a-aluminium matrix and the silicon phase, as the morphology of the silicon phase is affected by the heat treatment. A considerable scatter is observed in the neutron diffraction RS profiles, which is principally correlated to the presence (or absence) of pockets of porosity developed at the borders of the chessboard pattern. KW - Neutron diffraction KW - Additive manufacturing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565115 DO - https://doi.org/10.1007/s10853-022-07997-w SN - 1573-4803 VL - 57 SP - 22082 EP - 22098 PB - Springer Science + Business Media CY - Dordrecht AN - OPUS4-56511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rieder, Philipp A1 - Petrich, Lukas A1 - Serrano-Munoz, Itziar A1 - Mouiya, Mossaab A1 - Markötter, Henning A1 - Huger, Marc A1 - Bruno, Giovanni A1 - Schmidt, Volker T1 - Statistical analysis of grains and pores within polycrystalline Al2TiO5 ceramics, based on X-ray computed tomography N2 - Advanced statistical image analysis workflows were developed to segment and quantitatively evaluate 2D electron-backscatter diffraction (EBSD) maps and 3D synchrotron X-ray computed tomography (SXCT) volumes of a polycrystalline Al2TiO5 refractory composite that contains microcracks and pores. Several size, shape, and further geometric descriptors were determined for both the solid phase (Al2TiO5 grains) and the pore space. The resulting pore-size distribution is distinctly bimodal: coarse pores (tens to hundreds of micrometers), traced to incomplete powder compaction, coexist with fine pores generated during sintering. The two pore populations appear to be correlated with grain growth and crystallographic orientation in different ways. Finally, the descriptors obtained from the 2D EBSD and 3D SXCT data sets are internally consistent but complementary, highlighting the value of characterizations based on EBSD and SXCT in the microstructural study of refractory ceramics. KW - Synchrotron X-ray computed tomography KW - Electron-backscatter diffraction KW - Aluminum titanate KW - Morphological reconstruction KW - Image Segmentation KW - Statistical image analysis PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-643918 DO - https://doi.org/10.1016/j.matchar.2025.115602 SN - 1044-5803 VL - 229 SP - 1 EP - 13 PB - Elsevier Inc. AN - OPUS4-64391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruson, Danilo A1 - Serrano-Munoz, Itziar A1 - Fritsch, Tobias A1 - Markötter, Henning A1 - Galati, Manuela T1 - Revealing the (positive) role of porosity within polymeric additively manufactured lattices via X-ray computed tomography N2 - The mechanical properties of lattice geometries are known to be significantly influenced by a variety of manufacturing defects. This study investigates the influence of porosity on the mechanical behaviour of strut-based body-centred cubic (BCC) lattice structures produced with powder bed fusion with laser beam PBF-LB/P using PA2200 nylon powder. The study combines advanced techniques, including in-situ laboratory X-ray computed tomography (XCT), synchrotron XCT to visualise pores and roughness in high resolution at a single-cell level and image-based finite element analysis (FEA). The findings show that failure in thin-walled AM lattices is governed by the combined effects of porosity morphology, location, surface roughness, and cross-section reduction. The presence of internal porosity is found to attenuate both the amplitude of elastic modulus fluctuations and the severity of stress concentrations induced by surface irregularities. KW - Nylon Pa2200 KW - Laser powder bed fusion (PBF-LB) KW - Processing defects KW - Synchrotron X-ray computed tomography (XCT) KW - Digital volume correlation (DVC) KW - Image-based finite element simulations PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633245 DO - https://doi.org/10.1016/j.ijsolstr.2025.113488 SN - 0020-7683 VL - 320 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-63324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buljak, Vladimir A1 - Serrano-Munoz, Itziar A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Prasek, Marko A1 - Contillo, Adriano A1 - Mouiya, Mossaab A1 - Huger, Marc A1 - Bruno, Giovanni T1 - On the closure of thermally induced micro-cracks in aluminum titanate ceramics N2 - Aluminum Titanate (AT) refractory ceramics (as some other ceramic composites) are prone to microcracking, due to the thermal expansion anisotropy of AT and to the mismatch with the thermal expansion of the constituents. Such microcracks cause the room temperature Young's modulus to be only a fraction of that of the non-microcracked material. As a function of temperature, the Young's modulus increases non-linearly. Such increase suggests that microcracks close or even heal at high temperatures. Upon cooling, thermal stress accumulates again, and microcracks re-open. This cycle is fully reversible. While confirming the hysteretic behavior of the Young's modulus, we observe that the amount of microcracks (as determined by in-situ Synchrotron X-ray refraction radiography) decreases linearly upon heating. The apparent mismatch between the Young's modulus and the microcrack content dependence on temperature is explained by a simple FEM model. Such model employs cohesive elements upon cooling, in order to estimate the amount of initial microcracks. On purpose, the model does not include healing upon heating and only allows crack closure. It predicts that crack closure continuously occurs upon heating, thereby qualitatively reproducing the nearly linear dependence of the X-ray refraction signal. It is therefore concluded that the sudden and non-linear increase of Young's modulus with temperature is mainly caused by crack healing. Such finding agrees with previous work and paves the road to a more systematic separation of crack closure and healing in flexible ceramics. KW - X-ray computed tomography KW - X-ray refraction radiography KW - In-situ imaging KW - BAMline KW - Micromechanics KW - BESSY II PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-645082 DO - https://doi.org/10.1016/j.ceramint.2025.09.237 SN - 0272-8842 VL - 51 IS - 27 SP - 55141 EP - 55152 PB - Elsevier CY - Amsterdam AN - OPUS4-64508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Jakob A1 - Evans, Alexander A1 - Mishurova, Tatiana A1 - Ulbricht, Alexander A1 - Sprengel, Maximilian A1 - Serrano-Munoz, Itziar A1 - Fritsch, Tobias A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Bruno, Giovanni T1 - Diffraction-Based Residual Stress Characterization in Laser Additive Manufacturing of Metals N2 - Laser-based additive manufacturing methods allow the production of complex metal structures within a single manufacturing step. However, the localized heat input and the layer-wise manufacturing manner give rise to large thermal gradients. Therefore, large internal stress (IS) during the process (and consequently residual stress (RS) at the end of production) is generated within the parts. This IS or RS can either lead to distortion or cracking during fabrication or in-service part failure, respectively. With this in view, the knowledge on the magnitude and spatial distribution of RS is important to develop strategies for its mitigation. Specifically, diffraction-based methods allow the spatial resolved determination of RS in a non-destructive fashion. In this review, common diffraction-based methods to determine RS in laser-based additive manufactured parts are presented. In fact, the unique microstructures and textures associated to laser-based additive manufacturing processes pose metrological challenges. Based on the literature review, it is recommended to (a) use mechanically relaxed samples measured in several orientations as appropriate strain-free lattice spacing, instead of powder, (b) consider that an appropriate grain-interaction model to calculate diffraction-elastic constants is both material- and texture-dependent and may differ from the conventionally manufactured variant. Further metrological challenges are critically reviewed and future demands in this research field are discussed. KW - Laser-based additive manufacturing KW - Residual stress analysis KW - X-ray and neutron diffraction KW - Diffraction-elastic constants KW - Strain-free lattice spacing PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-538054 DO - https://doi.org/10.3390/met11111830 VL - 11 IS - 11 SP - 1830 PB - MPDI CY - Basel AN - OPUS4-53805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Roveda, Ilaria A1 - Mishurova, Tatiana A1 - Evans, Alexander A1 - Fitch, Andrew N. A1 - Haubrich, Jan A1 - Requena, Guillermo A1 - Bruno, Giovanni A1 - Serrano-Munoz, Itziar T1 - Evolution of interphase stress over a crack propagation plane as a function of stress relief heat treatments in a PBF‐LB/M AlSi10Mg alloy N2 - AbstractIn this study, we compare the residual stress state in a laser powder bed fusion (PBF‐LB/M) AlSi10Mg alloy in the as‐built (AB) condition with that after two different heat treatments (265 °C for 1 h, HT1; and 300 °C for 2 h, HT2). The bulk residual stress (RS) is determined using synchrotron X‐ray diffraction (SXRD), and near‐surface profiles are determined using laboratory energy‐dispersive X‐ray diffraction (EDXRD). The EDXRD results do not reveal any notable difference between the conditions at a depth of 350 μm, suggesting that the machining process yields a comparable residual stress state in the near‐surface regions. On the other hand, the SXRD results show that HT1 is more effective in relieving the bulk RS. It is observed that HT1 reduces the RS state in both the aluminium matrix and the silicon network. In addtion, HT2 does not have a significant impact on relaxing the RS as‐built state of the matrix, although it does induce a reduction in the RS magnitudes of the Si phase. It is concluded that the heat treatment stress relieving is effective as long as the Si‐network is not disaggregated. KW - Interphase residual stress KW - Laboratory energy-dispersive X-ray diffraction (EDXRD) KW - PBFLB/M AlSi10Mg alloy KW - Stress-relief heat-treatments KW - Synchrotron X-ray diffraction (SXRD) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597591 DO - https://doi.org/10.1111/str.12475 VL - 60 IS - 6 SP - 1 EP - 13 PB - John Wiley & Sons Ltd. AN - OPUS4-59759 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Serrano-Munoz, Itziar A1 - Pfretzschner, Beate A1 - Kromm, Arne A1 - Nadammal, Naresh A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Neuwirth, T. A1 - Schulz, M. A1 - Griesche, Axel T1 - High-resolution Bragg-edge neutron radiography detects grain morphology in PBF-LB/M IN718 N2 - One of the main advantages of metal additive manufacturing (MAM) techniques is their ability to produce components with site-specific microstructural features. Nevertheless, microstructural defects and lack of repeatability are still major concerns in MAM. In this study, a laser powder bed fusion (PBF-LB/M) IN718 material, produced using two different scan length vectors, is investigated using Bragg-edge neutron 2D imaging (BENI) combined with electron backscatter diffraction (EBSD) analysis. BENI is able to detect, on a macroscopic scale, process-induced changes in texture in a large field of view covering the entire sample (20×80 mm2). In addition, high-resolution BENI (HR-BENI), with a pixel size of 12.8 µm, provides a micro-scale examination of the local variations of texture and grain morphology, otherwise undistinguishable using the standard resolution. As such, HR-BENI offers a straightforward and detailed way of screening the integrity of MAM parts at cm-length scales. KW - Bragg-edge neutron 2D imaging (BENI) KW - Metal additive manufacturing (MAM) KW - IN718 PBF-LB/M KW - Crystallographic texture control KW - Electron backscatter diffraction (EBSD) PY - 2023 DO - https://doi.org/10.1016/j.mtla.2023.101827 SN - 2589-1529 VL - 30 SP - 1 EP - 6 PB - Elsevier CY - Amsterdam AN - OPUS4-57819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - 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 -