Phase formation and structures of quasicrystals and approximants in the Zn-Mg-(Ti, Zr, Hf) system

S. Ohhashi, E. Abe, M. Tanaka, A. P. Tsai

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The compositional regions for primitive (P) and face-centered (F) icosahedral quasicrystals (iQc) have been determined to be around Zn84Mg9Zr7 and Zn75Mg18Zr6, respectively. A 1/1 approximant of the F-type iQc was found to have a composition around Zn77Mg18Zr5. A similar tendency has been verified for the Zn-Mg-Hf system. No stable iQc was observed in the Zn-Mg-Ti system. High-resolution X-ray measurements performed with synchrotron radiation showed that the stable iQcs are highly ordered and contain less phason disorder. High-angle annular dark field (HAADF) scanning transmission electron microscopy observation of the 1/1 Zn-Mg-Hf approximant effectively revealed the Hf positions in the structure, whose local contrasts can be reasonably interpreted by a structural model where icosahedral and dodecahedral Hf clusters are mutually interpenetrated. Similar appearances of local contrasts were frequently observed in HAADF images of the F-type iQc, indicating that the iQc structure is also build up of icosahedral clusters that are almost identical to those in the 1/1 approximant.

Original languageEnglish
Pages (from-to)4727-4735
Number of pages9
JournalActa Materialia
Volume57
Issue number16
DOIs
Publication statusPublished - 2009 Sep

Keywords

  • Bergman cluster
  • Quasicrystal
  • Structure
  • Zinc-magnesium-zirconium

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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