X-ray microdiffraction studies to measure strain fields in a metal matrix composite

An x-ray diffraction microscope (XDM) has been used to map the strain field in a fiber-reinforced composite material. The monochromatic x-ray (11 keV) beam was focused by a phase zone plate to produce a focal spot of 1 x 4 mu m(2) on the specimen. The microfocusing method using a zone plate enables the XDM to produce a high spatial resolution of;1 mm. The change in the peak position of diffraction patterns due to interatomic spacing change, caused by stress in the sample, was measured by using a two-dimensional charge coupled device detector. The radial residual strain field in the fiber-reinforced composite (SCS-6/Ti-14Al-21Nb) was measured from diffraction patterns with a sensitivity of similar to 10(-4) and an average standard deviation of 9.4 x 10(-5). [S0034-6748(99)02901-9].