X-ray diffraction study of decagonal Al—Co—Ni as a function of composition

• Published in: Zeitschrift für Kristallographie. Crystalline materials Vol. 219; no. 10; pp. 606 - 613
• Main Authors: Katrych, Sergiy, Steurer, Walter
• Format: Journal Article
• Language: English
• Published: De Gruyter Oldenbourg 01.10.2004
• ISSN: 2194-4946; 2196-7105
• DOI: 10.1524/zkri.219.10.606.50824

The evolution was studied of structural order/disorder phenomena across the wide stability field of the decagonal phase in the system Al—Co—Ni. Full single-crystal X-ray diffraction data sets were collected of 31 samples annealed at 900 °C. Based on reciprocal space reconstructions of the imaging-plate-scanner data, the variation in Bragg as well as in diffuse scattering is discussed in detail. The samples were also characterized metallographically, by powder X-ray diffraction, differential thermal analysis and energy-dispersive X-ray spectroscopy. The (quasi)lattice parameters vary smoothly over the stability range of decagonal Al Co Ni (8 ≤ ≤ 20). A smooth variation is also observed for the diffuse scattering related to the ≈8 Å superstructure. These observations indicate a continuous ordering process at 900 °C from the basic Co-rich phase via the type II and type I superstructures to the basic Ni-rich phase.