X-ray microtomographic studies of metal matrix composites using laboratory X-ray sources

X-ray microtomography (XMT) is a non-destructive technique that allows the internal structure of a material to be imaged by the spatial distribution of its linear X-ray absorption coefficients. This paper demonstrates the use of XMT to investigate: (1) the distribution of TiB2 reinforcement in composites formed by powder processing; (2) the local void volume fraction as a function of position in highly deformed regions of failed tensile specimens of SiC-reinforced material allowing a valid damage parameter to be defined at high strains; (3) absorption coefficients measured at different energies simultaneously using a multichannel analyser which can sometimes be used to separate linear absorption changes due to (a) density variations and (b) compositional variations in individual voxels; and (4) the use of sequential sections to provide a three-dimensional representation of the failed specimens.