X-ray microtomography of materials

X-ray microtomography allows imaging of the interior microstructure of materials non-destructively and with spatial resolution which can approach that of optical microscopy (typically, no better than 1 μm in samples whose cross-sectional diameter is on the order of 1 mm, and 10 μm for 10 mm specimens). First, X-ray microtomography's origin in medical imaging and the physics behind computed tomography are reviewed. Summaries of apparatus, radiation sources, data collection schemes, and of materials applications follow. To date, most materials applications fall into one of four areas: inorganic matrix composites, transport in porous media, calcified tissue, and fatigue crack closure. Details of studies in each area highlight the advantages X-ray microtomography brings, and the final section focuses on future directions suggested by recent work using imaging modalities other than X-ray attenuation.