Application of Microbeam X-Ray Diffraction Study by Using Synchrotron Radiation Source to the Investigation of Fracture of Materials.

A cyclic plastic zone area near fatigue-fractured surface was studied using a back-reflection camera and high intensity, microbeam, synchrotron radiation X-ray source (SR) in order to measure the variation of the stress intensity factor range (ΔK) along the fatigue fracture. The existence of subgrains within the cyclic plastic region was shown by the appearance of small spots in the Debye-Scgerrer rings of the imaging plate. This effect did not exist outside of the cyclic plastic area. The size of the cyclic plastic zone below the surface was estimated from the relation between the number of spots in a Debye-Scherrer ring and the depth from the fracture surface. ΔK was measured from this relation. A synchrotron X-ray source made these measurements possible within a high positional resolution and a reasonable period of exposure time. Such microbeam X-ray diffraction technique is also applicable on the measurement of residual stress in localized region of single crystal and residual stresses in Si single crystal could be measured by using 30 μm in diameter of X-ray beam.