Defects which exhibited a loop-shaped contrast, and which had previously been observed - using X-ray topography - in AlCuFe and AlPdMn quasi-crystals, were related to inhomogeneities (holes, precipitates) which were revealed by phase radiography and tomography. The evolution of the defects during annealing provided evidence as to their nature and formation. The results were explained with regard to existing structural models for quasi-crystals. Those for holes were in reasonable agreement with the predictions of a theoretical model which had been intended to describe the structure of icosahedral AlPdMn quasi-crystals in terms of an hierarchical self-similar packing of overlapping atomic clusters.

The Value of X-Ray Imaging for the Study of Defects in Real Quasicrystals. J.Gastaldi, L.Mancini, E.Reinier, P.Cloetens, W.Ludwig, C.Janot, J.Baruchel, J.Härtwig, M.Schlenker: Journal of Physics D, 1999, 32[10A], A152-9