High energy X-ray micro-tomography for the characterization of thermally fatigued GlidCop specimen

Abstract

The expected increases in the thermal power of X-ray beams produced at the third-generation synchrotron radiation facilities may exceed the heat-load capabilities of the existing high-heat-load components with which the beams interact. An X-ray beam shutter is an example of such components. Typically made of GlidCop, it is used, as needed, to block the X-ray beam from entering the experimental area. Analyses show that the planned 50% increase in storage ring beam current (and thus beam heat load) at the Advanced Photon Source (APS) will result in plastic strain in the shutter limiting its operational life. In order to develop a predictive model to estimate the number of cycles to failure, cooled GlidCop samples were thermally cycled 10,000 times under the high heat load of an X-ray beam from two inline APS undulators. Samples are examined for cracks, and crack size information is extracted for use in the model. In this paper, following some introductory remarks, we report on the characterization of the micron-size fatigue cracks in a sample GlidCop using high-energy X-ray absorption and phase-contrast tomography. It is shown that the current set up at beamline 1-ID at the APS is capable of nondestructive reconstruction of internal structure of the fatigued part with a resolution of 3 μm, which may further be improved to about 1 μm.