The expansion behavior of particulate reinforced AlSiC metal matrix composites (MMCs) during a thermal cycle shows anomalies at temperatures above 250C, explained by viscoplastic matrix deformations and changing void volume fractions. Volumetric images of the sample acquired by synchrotron tomography at several temperatures between 30C and 400C are used to analyze the void kinetics. These high-resolution low-contrast 3D + T images are not aligned, thus only allowing quantitative comparisons over areas comprising many voids. Analysis of specic voids at various temperatures was not feasible, due to the three-dimensional misalignment.
We present a 3D registration approach based on mutual information that allows for sub-pixel accurate registration. A maximum intensity projection (MIP) may be used for a manual pre-alignment. Further software tools for the analysis of void kinetics of AlSiC provide linked views for 2D slices, 3D isosurfaces, volume rendering, as well as overlaid contours (isolines) of multiple images on an arbitrarily positionable cutting plane, and the calculation of a shape factor. By registering the volumetric datasets, we were able to visualize the shrinkage and expansion of a specific void during thermal cycling between room temperature and 400C and to analyze the change of quantitative properties of specific voids - including volume, surface, shape factor - resulting from temperature changes.