Abstract
Three high-resolution / high-energy phase-contrast X-ray nano-tomography (XNT) techniques were tested, with the spatial resolution, contrast, and artefacts being evaluated. All the experiments utilized apodization Fresnel zone plates (A-FZP), which have been recently developed for the purpose of imaging characteristics improvement, taking advantage of the A-FZP’s secondary benefit that its thicker inner zone makes it readily applicable for use with high X-ray energies. The techniques employed in the present study were the imaging-type XNT combined with Zernike phase-contrast optics, the X-ray schlieren phase-contrast method, and the defocusing phase-contrast method. All the methods successfully recognized a density difference of 3.7 % between α and β grains in a Ti-6Al-4V alloy at an X-ray energy of 20 keV, together with an excellent spatial resolution within a scanning time of 1h. The Zernike phase-contrast method was then successfully applied to in-situ XNT observation of the transformation behavior of retained austenite in a duplex carbon steel at an X-ray energy of 20 ~ 37.7 keV. The characteristic local transformation behavior of the retained austenite was revealed through a series of 3D images and quantitative data obtained from the 3D images.
