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  • 1980-1984  (7)
Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 16 (1983), S. 295-303 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The integrated X-ray reflectivity of elastically bent, but otherwise perfect, crystals are calculated for Laue-type reflections covering the entire curvature range. Anomalous transmission and elastic anisotropy are taken into account, and it is shown that both these effects affect appreciably the reflected intensities for both weakly and strongly bent crystals. The validity of the reflectivity-versus-curvature relation thus obtained is experimentally confirmed for a number of reflections from silicon crystals. The implications of the experimental results to brittle fracture are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 594-601 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Dislocation-free silicon crystals of ({\bar 2 \bar 1 \bar 1}) orientation with a hyperbolic notch, subjected to tensile deformation at 1073 K, were used as model material for the analysis of the induced plastic zone. The results obtained by X-ray topography and X-ray rocking-curve measurements were compared to theoretical calculations and predictions based on continuum mechanics. Good agreement between experiment and theory was obtained regarding the shape of the plastic zone, the contribution of the active slip systems to the size of the plastic zone and the direction of the maximum plastic strain trajectory in the zone. Discrepancies between experiment and theory regarding the symmetry relation of the plastic zone lobes and the dislocation density near the notch tip were attributed to the interactions and resulting work-hardening. These aspects were not taken into account in calculations of continuum mechanics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 14 (1981), S. 352-353 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 16 (1983), S. 606-610 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: A method is presented for enhancing the fluorescence of the silver precipitates in the microfluorescent analysis of X-ray topographs by scanning electron microscopy or similar electron microprobes. The method is based on the indirect excitation of the silver fluorescence by depositing a thin suitable metal film on the emulsion of a nuclear track plate. Theoretical aspects of the method are presented and experimentally verified. The method was applied to determine the elastic strain distribution in a bent silicon plate containing a hole by measuring the opacities of the exposed and developed topograph obtained from the specimen.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 13 (1980), S. 290-296 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The strain distribution in the vicinity of the notches of a double-notched, elastically bent silicon crystal was determined by measuring the diffracted X-ray intensities. The measurements were carried out on traverse-oscillation topographs of a crystal section extending through both notches. Strain distributions were determined by measuring the local densities of silver deposits (measurements of `opacities') with a scanning electron microscope. It was shown that both the density range and spatial resolution of X-ray densitometry were larger by an order of magnitude than those of optical densitometry. The strain concentration factors associated with the notches were measured experimentally and calculated by continuum mechanics. The results were in satisfactory agreement. Also, the experimentally found rise of strains, to a maximum in the critical area adjacent to the notch root, followed the trend predicted by continuum mechanics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 15 (1982), S. 423-429 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: Long-range, elastic strains emanating from stress raisers, such as holes and inclusions, were investigated in bent silicon crystals which functioned as a model material. The strains and strain interactions were characterized by X-ray Pendellösung fringe topography and were quantitatively evaluated by X-ray intensity measurements of transverse-oscillation topographs. Improvement of strain measurements were obtained by considering the contribution of anomalous transmission to the intensity measurements and by deposition of an appropriate metal film on the developed topograph to heighten the fluorescence of the silver grains in the emulsion. The strain gradient emanating from a bent specimen containing a hole was experimentally determined and the results were compared to calculations based on continuum mechanics having closed-form solution. Good agreement between experiment and theory was obtained. The dependence of strain interaction on interflaw distance was experimentally demonstrated for specimens containing two holes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 16 (1983), S. 89-95 
    ISSN: 1600-5767
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Geologie und Paläontologie , Physik
    Notizen: The method represents an extension of a previously developed X-ray double-crystal diffractometer method when a film was used to record the crystallite reflections, each reflecting crystallite being regarded as the second crystal of a double-crystal diffractometer. By utilizing a position-sensitive detector (PSD) with interactive computer controls, the tedious and limiting task of data acquisition and analysis is greatly simplified. The specimen is irradiated with crystal-monochromated radiation and the numerous microscopic spots emanating from the reflecting crystallites are recorded separately by the position-sensitive detector and its associated multichannel analyzer at each increment of specimen rotation. An on-line minicomputer simultaneously collects these data and applies the necessary corrections. This process is then automatically repeated through the full rocking-curve range. The computer carries out the rocking-curve analysis of the individual crystallite reflections as well as that of the entire reflecting crystallite population. The instrument is provided with a specimen translation device which permits analysis of large sections of solid specimens. Thus, sites of local lattice defects induced either mechanically, chemically or by radiation can rapidly be established and quantitatively determined in terms of rocking-curve parameters as well as imaged by X-ray topography, by inserting a film in front of the PSD. The versatility and usefulness of the method is demonstrated by examples given from studies of fracture, fatigue and stress-corrosion cracking of commercial alloys.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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