A study was made of dislocations, in decagonal Al70Ni21Co9 quasicrystals, by means of diffraction contrast analysis as well as convergent-beam electron diffraction in a transmission electron microscope. The Ni-rich quasicrystals exhibited diffraction patterns which were characteristic of the basic Ni decagonal phase; exhibiting almost no diffuse scattering. This phase was grown in the form of large single quasicrystals. The 2-beam bright-field images revealed an homogeneous background and no striation contrast as reported for other Al-Ni-Co decagonal phases. The weak contrast-extinction condition was observed for the first time here in a 2-dimensional quasicrystal.

Dislocations in Basic-Nickel Decagonal Al-Ni-Co Single Quasicrystals. P.Schall, M.Feuerbacher, K.Urban: Philosophical Magazine Letters, 2004, 84[7], 471-81