Autori: I. Tiseanu, T. Craciunescu, G.V. Aldica, M. Iovea
Editorial: Advanced Materials Research, 47-50, p.698-701, 2008.
The potential of X-ray micro-tomography in characterizing the relevant material issues as
identified during manufacturing processes was investigated. For this purpose, the 3D X-ray
micro-tomography (XRmT) analysis was applied to the characterization of structural integrity of
Nb3Sn superconducting wires of differing topology and the evolution of the density distribution of
ceramic samples manufactured by Field Assisted Sintering Techniques (FAST). The latter technique
was used to consolidate the ceramic, metal (Ni) and composite powders (MgB2). The usual scanning
electron microscope (SEM) technique was enhanced by the high resolution XRmT in order to describe
the volumetric density distribution before sintering and at different moments of the thermal cycle.
Two types of samples sintered Ni and high density MgB2 superconductors with typical volume of
0.8÷1.5 10-9 m3 were sampled at space resolution around 5 microns. For the sintered Ni, the 3D
reconstructed volumes revealed the grain connectivity, necks formation and particle rearrangement in
the densification process. The XRmT analysis was essential in explaining the differences in
superconducting properties of MgB2 samples in terms of different volumetric structures. For the
Nb3Sn multifilamentary wire which is at basis of many practical superconductors, the 3D tomography
enabled the determination of the number of inter-filament contacts as well as the twist-pitch
parameter. Advantages of our method versus the invasive etching techniques for the determination of
the twist-pitch parameter were outlined.
Cuvinte cheie: X-ray micro-tomography, Field Assisted Sintering Techniques, MgB2 superconductor,