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 - Mechanical Engineering KW - Maskinteknik PY - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-510763 SN - 17426588 VL - 1145 SP - 012044 PB - IOP AN - OPUS4-51076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Serrano Munoz, Itziar A1 - Evsevleev, Sergei A1 - Laquai, René A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Damage characterization via 2D and 3D X-ray refraction techniques N2 - We present two examples of the potential of synchrotron X-ray refraction techniques. First, we focus on the 3D imaging of hydrogen assisted cracks in an EN AW – 6060 aluminium alloy which are otherwise undetected by absorption-based CT. The second work is a quantitative analysis of the damage evolution in an Al/Al2O3 Metal Matrix Composite during interrupted in-situ tensile load. T2 - International Conference on Tomography of Materials & Structures CY - Cairns, Australia DA - 22.07.2019 KW - X-ray refraction KW - Analyzer-based imaging KW - Aluminum alloy KW - Metal matrix composite KW - Damage characterization PY - 2019 AN - OPUS4-48604 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evsevleev, Sergei A1 - Paciornik, Sidnei A1 - Gollwitzer, Christian A1 - Bruno, Giovanni T1 - Application of deep learning to the segmentation of synchrotron X-ray tomography data of multiphase metal matrix composites N2 - The 3D microstructure of an Al alloy matrix composite with two ceramic reinforcements was investigated by synchrotron X-ray tomography. A deep learning algorithm was used for the segmentation of four different phases. We show that convolutional networks with the U-Net architecture are able to solve complex segmentation tasks with small amount of training data. T2 - International Conference on Tomography of Materials & Structures CY - Cairns, Australia DA - 22.07.2019 KW - Synchrotron X-ray tomography KW - Deep learning KW - Segmentation KW - Metal matrix composite PY - 2019 AN - OPUS4-48606 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Evsevleev, Sergei A1 - Mishurova, Tatiana A1 - Sevostianov, Igor A1 - Garcés, Gerardo A1 - Requena, Guillermo A1 - Cabeza, Sandra A1 - Bruno, Giovanni T1 - Load transfer and damage evolution in multiphase Al alloy matrix composites under uniaxial compression N2 - Aluminum alloys are extensively used in the automotive industry. Particularly, squeeze casting production of Al-Si alloys is employed in the conception of metal matrix composites (MMC) for combustion engines. Such materials are of a high interest since they allow combining improved mechanical properties and reduced weight and hence improve efficiency. We investigate two types of MMCs, which can be potentially used for production of combustion engine pistons: 1) a near-eutectic cast AlSi12CuMgNi alloy reinforced with 15%vol. Al2O3 random planar oriented short fibers and 2) the same alloy reinforced with 7%vol. Al2O3 random planar oriented short fibers + 15%vol. SiC particles. Complex 3D microstructure of the samples in as-cast condition, consisting of four and five phases (Al matrix, eutectic Si, intermetallics, Al2O3 fibers and SiC particles) was investigated by synchrotron computed tomography (CT). Advanced methods based on machine learning were applied for segmentation of all phases. This allowed extracting quantitative information such as volume fraction, shape and interconnectivity of every phase. In-situ compression tests during neutron diffraction experiments were used to track the load transfer among phases, while CT on pre-strained samples to monitor and quantify damage. A micromechanical model was developed to simulate the evolution of the internal stress of each phase during uniaxial compression. We showed that in composites with the Al2O3 fiber mat plane perpendicular to the load axis the Al-alloy matrix presents a large hydrostatic stress component, i.e. undergoes compression also in the direction transverse to the external load. This feature holds with and without the addition of SiC ceramic reinforcement and is absent in the case when the Al2O3 fiber mat plane is parallel to the load axis. We show, that the intermetallics play a decisive role at very high loads, when all other reinforcement phases suffer (extensive) damage. The addition of SiC particles does alleviate the load on the Al2O3 fibers, on the eutectic Si, and on the intermetallic phases in both cases of parallel and orthogonal (to the load axis) Al2O3 fiber orientation. Apart from the beneficial addition of ceramic reinforcement, the presence of intermetallic phase and eutectic silicon, forming an interconnected network even at high loads, when single particles break, confers peculiar properties to these multi-phase composites. T2 - The 3rd International Conference on Light Materials CY - Manchester, UK DA - 05.11.2019 KW - Aluminum alloy KW - Metal Matrix Composite KW - Computed tomography KW - Neutron diffraction KW - Stress analysis KW - Load partition PY - 2019 AN - OPUS4-49640 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-471931 UR - http://stacks.iop.org/1742-6596/1145/i=1/a=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 - 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-474070 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 - JOUR A1 - Evsevleev, Sergei A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Kupsch, Andreas T1 - Refraction driven X-ray caustics at curved interfaces N2 - X-ray refraction related interaction has received rising interest since about two decades in the field of imaging, beam shaping and analysis although being discovered a century ago. Due to refraction at interfaces in inhomogeneous media X-rays undergo natural focusing (or defocusing) of waves, revealing caustics. Such Kind of intensity patterns are well-known for visible light, but have been sparsely discussed for X-rays. The Variation of irradiation density may be predicted in case of known shapes. Analogously to light optics, the intensity distributions cover several orders of magnitude including complete extinction. The partly convergent (and divergent) caustic stripes originate from narrow zones of typical size of some 10−6 of the boundary curvature radius. For the deflection of plane wave synchrotron radiation (energy in the range of some keV to some ten keV) at rods and tubes of several μm diameter, we find good Agreement between experiments and modeling by ray tracing according to Snell’s law without additional diffraction contributions. Apart from Basic Research implications, caustics may influence the performance of irradiation technologies such as sterilization or molecular cross-linking. KW - X-ray caustics KW - X-ray refraction KW - Irradiation KW - Radiation shielding KW - Synchrotron Radiation PY - 2019 UR - http://www.sciencedirect.com/science/article/pii/S0168900218314591 U6 - https://doi.org/10.1016/j.nima.2018.10.152 SN - 0168-9002 SN - 1872-9576 VL - 916 SP - 275 EP - 282 PB - Elsevier AN - OPUS4-46924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -