Abstract
A screw type of dislocation in Al70Ni10Co20 and Al75Ni10Fe15 decagonal quasicrystals has been observed, for the first time, by means of transmission electron microscopy. An edge type of dislocation and some microdomain structures have also been observed. Conventional contrast analysis shows that the Burgers vectors are parallel to the tenfold axis for both screw- and edge-type dislocations while the displacement vector of the domain boundary is along a twofold axis of the decagonal quasicrystals.