ira 
Figure 7: Tomographic slice through the density distribution of a polystyrene foam (left). Volume 
dense composite rendering of the foam cell (right). 
tluctuations (the 
on the figure), 
200 pire 
Figure 8: Model metal matrix composite (Al + 20 % Z10,/SiO; spheres) with a heterogeneous 
structure. 2D reconstructed slice (left) and 3D rendering (right). 
Damage 
A testing device has been especially designed (4) to allow mechanical tests to be performed in situ 
during tomography experiments. The device, mounted directly on the turntable of the beam line, 
includes a polymer tube which transfers the efforts from the top to the bottom grip. This tube gives 
eo of 1457003 negligible attenuation of the x-rays under each view angle and then allows a scan to be recorded 
Mei} . under load. This setup has been used to study the extension of damage in heterogeneous systems 
on, pris like SiC/Al metal matrix composites. In this case, phase contrast was of crucial help because SiC 
ons, Th pe particles and Al matrix x-ray attenuation is nearly the same , the particles were distinguished in the 
supposed 0 reconstructed images thanks to the edge detection of their interface with Al. As previously 
yz canbe sent mentioned, phase contrast fringes also improved the detection of the particle cracks. This study has 
permitted to show that the evolution of damage in the bulk of the material, though qualitatively 
similar, was strongly different in a quantitative way to that at the surface. The amount of broken 
particles was nearly twice bigger inside the sample than at the surface (4). 
Another important study in the field of materials science concerns the growth of cavities in ductile 
matrices. We were able to image the growth of pores around ceramic particles and are currently 
75