Synchrotron radiation refraction topography for characterization of lightweight materials

摘要

The employment of synchrotron radiation for refraction topography of materials has considerable advantages over standard x-ray sources. The much higher beam intensity and the parallel and monochromatic radiation provide faster measurements and better angular and spatial resolution. X-ray refraction techniques image the inner surface and interface concentration of micro-structured materials. This effect of x-ray optics is additional to small-angle scattering by diffraction, when the scattering objects reach micrometre dimensions. We have developed x-ray refraction techniques within the last decade in order to meet the growing demands for improved non-destructive characterization of high-performance composites, ceramics and other low-density materials. Sub-micron particle dimensions, the pore size of ceramics, the crack density distribution and single fibre debonding within damaged composites can be measured and visualized by computer-generated interface topographs. For this purpose investigations are now being performed at the new hard x-ray beamline of the Federal Institute for Materials Research and Testing (BAM) at BESSY, Berlin. This BAMline provides monochromatic radiation of photon energies from 5 to 60 keV from a double multilayer and/or a double-crystal monochromator. A separate instrument is dedicated to the further development and application of synchrotron radiation refraction (SRR) topography. Different from conventional small-angle scattering cameras with collimating slits and pinholes, scattering angles down to a few seconds of arc are selected by a single-crystal analyser, similar to a Bonse-Hart diffractometer. A 20 mum spatial resolution of the scattering micro-structures is achieved by a CCD camera with a fluorescent converter. First SRR topographs of aircraft composites [carbon fibre-reinforced plastics (CFRP), carbon fibre-reinforced ceramics (C/C), metal matrix ceramics (MMC)] will be reported. Copyright (C) 2004 John Wiley Sons, Ltd.