Growth and structure of Al-Cu-Co single quasi-crystals.

One- and two-subgrain single quasi-crystals of Al-Cu-Co alloy were obtained by the modification of inclined front crystallization (IFC) method. A model of transition layer has been suggested, which enabled the determination of the quantitative relation between parameters of single quasi-crystals subgrains and components of the inclined front crystallisation angle and the growth rate. On the basis of a transition layer model of two-subgrain single quasicrystals a method was prepared to determine thermal supercooling on the front of decagonal phase growing from the molten phase and its dependence on the growth rate. The mechanism of single quasi-crystals of Al-Cu-Co alloy has been found to change at the growth rate of around 0.25 mm/min. It has been determined that low-angle boundaries generate phasonic defects, which may propagate along a tenfold symmetry axis. The presence of subgrain boundaries in single quai-crystals increases the phasons concetration in them.