The degree of perfection of icosahedral quasicrystalline grains of various alloys, as-grown or annealed, had been studied previously and it had been shown that some of them were much more perfect than others. Here, attention was concentrated on a slice of a grain of Al-Pd-Mn alloy. An extensive synchrotron X-ray topographic investigation was made of strains and defects in this grain; combined with phase-contrast radiography and high-resolution X-ray diffraction examination. Very little 2-lobe contrast associated with pores, and no loop-shaped contrast, was observed in X-ray topographs, but straight-line segments and band contrast were identified. Line segments could be considered to be a result of the climbing of polygonal dislocation loops, as observed by transmission electron microscopy. This indicated that most strains and defects observed in quasicrystalline grains, at room temperature, were the result of stresses (external and internal) which acted after growth.

Synchrotron X-Ray Diffractometry and Imaging of Strains and Defects in Icosahedral Quasicrystal Grains. J.Gastaldi, T.Schenk, L.Mancini, H.Klein, J.Härtwig, S.Agliozzo, J.Baruchel, M.de Boissieu: Philosophical Magazine, 2006, 86[36], 5897-908