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Proceedings Paper

X-ray refraction topography and computed tomography for NDE of lightweight materials (Keynote Paper)
Author(s): Bernd R. Mueller; Axel Lange; Michael Harwardt; Manfred P. Hentschel; Bernhard Illerhaus; Juergen Goebbels; Joachim Bamberg; Falko Heutling
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Paper Abstract

X-Ray Refraction Topography techniques are based on Ultra Small Angle Scattering by micro structural elements causing phase related effects like refraction and total reflection at a few minutes of arc as the refractive index of X-rays is nearly unity (1x10-5). The extraordinary contrast of inner surfaces is far beyond absorption effects. Scanning of specimens results in 2D-imaging of closed and open pore surfaces and crack surface density of ceramics and foams. Crack orientation and fiber/matrix debonding in plastics, polymers and ceramic composites after cyclic loading and hydro thermal aging can be visualized. In most cases the investigated inner surface and interface structures correlate to mechanical properties. For the exploration of Metal Matrix Composites (MMC) and other micro structured materials the refraction technique has been improved to a 3D Synchrotron Refraction Computed Tomography (SR-CT) test station. The specimen is situated in an X-ray beam between two single crystals. Therefore all sample scattering is strongly suppressed and interpreted as additional attenuation. Asymmetric cut second crystals magnify the image up to 50 times revealing nanometer resolution. The refraction contrast is several times higher than "true absorption" and results in images of cracks, pores and fiber debonding separations below the spatial resolution of the detector. The technique is an alternative to other attempts on raising the spatial resolution of CT machines. The given results yield a much better understanding of fatigue failure mechanisms under cyclic loading conditions.

Paper Details

Date Published: 9 May 2005
PDF: 8 pages
Proc. SPIE 5766, Testing, Reliability, and Application of Micro- and Nano-Material Systems III, (9 May 2005); doi: 10.1117/12.599708
Show Author Affiliations
Bernd R. Mueller, Federal Institute for Materials Research and Testing (Germany)
Axel Lange, Federal Institute for Materials Research and Testing (Germany)
Michael Harwardt, Federal Institute for Materials Research and Testing (Germany)
Manfred P. Hentschel, Federal Institute for Materials Research and Testing (Germany)
Bernhard Illerhaus, Federal Institute for Materials Research and Testing (Germany)
Juergen Goebbels, Federal Institute for Materials Research and Testing (Germany)
Joachim Bamberg, MTU Aero Engines GmbH (Germany)
Falko Heutling, MTU Aero Engines GmbH (Germany)


Published in SPIE Proceedings Vol. 5766:
Testing, Reliability, and Application of Micro- and Nano-Material Systems III
Robert E. Geer; Norbert Meyendorf; George Y. Baaklini; Bernd Michel, Editor(s)

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