Czochralski growth and X-ray topographic characterization of decagonal AlCoNi quasicrystals

Abstract

International audienceLarge single crystals of the decagonal AlCoNi phase were reproducibly grown by the Czochralski method from Al-rich melts. By using native seeds, it was possible to grow crystals with well-defined orientations, e.g. along the 10-fold periodic axis or parallel to one of the 2-fold axes. Quasicrystals, that had been pulled in periodic or quasiperiodic directions, were characterized by X-ray transmission topography at the synchrotron source (ESRF) and at laboratory sources using the Lang technique. Because of the metallurgical homogeneity of the grown quasicrystals, lattice parameter differences did not contribute to the topographic contrast, instead, orientation contrast dominated. A column-like substructure along the periodic direction could be revealed. From this it is concluded, that crystal growth along a two-fold direction might be favourable with respect to minimizing defect spreading

Influence of the substrate temperature and deposition flux in the growth of a Bi thin film on the ten-fold decagonal Al-Ni-Co surface

“…The single grain decagonal Al 71.7 Ni 18.7 Co 9.6 quasicrystal grown by the Czochralski method from an Al-rich melt [15], which is S1-type phase, was cut perpendicular to the ten-fold axis and then mechanically polished using diamond paste down to 0.25 mm.…”

Single crystal growth of Al-based intermetallic phases being approximants to quasicrystals

“…Therefore, they can be primarily crystallized only below their individual peritectic temperature and exact phase diagram information is an important issue in planning the growth strategy. Earlier success in single crystal growth of d-AlCoNi [8,16] was essentially supported by the detailed knowledge of the Al-rich part of the ternary Al-Co-Ni phase diagram based on the excellent work of Gödecke [17]. An isothermal section at 1050 1C of a part of this phase diagram [18] is shown in Fig.…”

X‐ray topography study of deformed composites obtained by directional solidification of Al‐Cu‐Co alloy

“…X-ray reflection topography is a suitable method for this purpose [4]. This method enables the visualisation of local lattice deformation, sub-grain boundaries and other defects in single crystals [5][6][7]. The method may also be applied for the study of composites.…”