ON THE DETERMINATION OF BURGERS VECTORS OF TYPE-B DISLOCATIONS IN AN AL70CO15NI15 DECAGONAL QUASI-CRYSTAL BY CONVERGENT-BEAM ELECTRON-DIFFRACTION

Type B dislocations with Burgers vectors parallel to the twofold axes of the Al70Co15Ni15 decagonal quasicrystal were studied by means of el ectron diffraction contrast imaging and defocus convergent-beam electr on diffraction techniques. Two kinds of Burgers vector of the type B d islocations were determined, both being parallel to a twofold axis A2P of the decagonal quasicrystal. The components \b(parallel-to)\ of the Burgers vector b = [0010 - 10] in physical space and the component \b (perpendicular-to\ of the Burgers vector in complementary space are 0. 186 and 0.115 nm respectively, with a ratio tau of 1.618. The componen ts for b = [010 - 11] are 0.302 and 0.071 nm with a ratio tau3 of 4.23 5.