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AbstractAbstract
[en] The hard spectrum which is available on the BAMline at Berlin's synchrotron BESSY offers the rare opportunity to perform high-resolution X-ray imaging experiments with a partially coherent beam. This thesis work reports on the development of a new tomography system, including Fresnel-propagated imaging, and its application to three specific materials science problems from the fields of engineering materials, biology and earth science. Static and dynamic 2D and 3D images were recorded from a variety of aluminum-based alloys. Coarsening of particle agglomerates (at high solid volume fraction) in liquid solution, as well as rheological properties of semi-solid alloys are thus characterized. Dentin is characterized by a quasi-parallel arrangement of micrometer-sized tubules. This work shows how high-resolution 3D images of water-immersed tooth dentin are recorded, and detailed simulations of the optical wave propagation reveal that Fresnel-images contain additional information about the dense cuff of peritubular dentin surrounding the tubules. The cuff thickness can be extrapolated from the interference fringes that form the propagated images of tubules. Absorption and Fresnel-propagated X-ray tomography are applied to measure samples of different rocks before and after mechanical compression nondestructively. In a first approach, limestone and greywacke are investigated, representing two sedimentary rocks of different grain size. Basalt and granite are tested in a second approach to compare different rock types. Development of cracks is observed in all materials, leading to fracture when increasing mechanical load is applied. In this work, relatively small mm-sized samples are used in order to test a classical fracture model wherein micro-flaws initiate the formation of larger cracks. For the first time, Fresnel-propagated imaging is applied to rock samples, highlighting micrometer-sized intergranular porosity as well as different material phases. The latter is shown to indicate a preferred crack orientation. (orig.)
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Source
9 Oct 2007; 210 p; Diss. (Dr.rer.nat.)
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation
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AGGLOMERATION, ALUMINIUM BASE ALLOYS, BASALT, BEAM TRANSPORT, BESSY STORAGE RING, COHERENT RADIATION, CRACK PROPAGATION, DENTIN, EXTRAPOLATION, GRAIN SIZE, GRANITES, GRAYWACKE, HARD X RADIATION, INTERFERENCE, LIMESTONE, ORIENTATION, PHOTON BEAMS, POROSITY, SYNCHROTRON RADIATION, SYNCHROTRON RADIATION SOURCES, THICKNESS, TOMOGRAPHY, WAVE PROPAGATION, X-RAY RADIOGRAPHY
ALLOYS, ALUMINIUM ALLOYS, BEAMS, BREMSSTRAHLUNG, CARBONATE ROCKS, DIAGNOSTIC TECHNIQUES, DIMENSIONS, ELECTROMAGNETIC RADIATION, IGNEOUS ROCKS, INDUSTRIAL RADIOGRAPHY, IONIZING RADIATIONS, MATERIALS TESTING, MATHEMATICAL SOLUTIONS, MICROSTRUCTURE, NONDESTRUCTIVE TESTING, NUMERICAL SOLUTION, PLUTONIC ROCKS, RADIATION SOURCES, RADIATIONS, ROCKS, SANDSTONES, SEDIMENTARY ROCKS, SIZE, STORAGE RINGS, TESTING, VOLCANIC ROCKS, X RADIATION
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