We report the formation of a primitive icosahedral quasicrystal with increased stability in Al-Mn-Be alloys close to the compound Al15Mn3Be2by melt spinning and injection casting. The crystal structure of this compound was unknown. We show that in as-cast as well as heat treated condition the intermetallic phase HI has a hexagonal structure with lattice parameters a = 1.2295 nm and c = 2.4634 nm. The space group is P63/mmc. In the injection-cast samples, the quasicrystal coexists with another closely related hexagonal phase H2 with a =1.2295nm and c = 1.2317nm with a possible space group of P6/mmm. This phase exhibits specific orientation relationships with the icosahedral quasicrystal given by hcx//2/QCand hex//5/QCwhere 2/qCand 5fQCrepresent twofold and fivefold axes respectively. Electron diffraction patterns from both phases exhibit a close resemblance to the quasicrystalline phase. It is shown that the HI phase is closely related to μ-Al4Mn with the same c parameter while the a parameter is reduced by τ. Following Kreiner and Franzen, it is postulated that both structures (HI and H2) can be understood by a simple hexagonal packing of I13 clusters.
|Number of pages||14|
|Journal||Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties|
|Publication status||Published - 2002 May|
Bibliographical noteFunding Information:
ACKNOWLEDGEMENTS We thank Professor K. H. Kuo (Beijing Laboratory of Electron Microscopy) for useful discussions. This work was supported by the Creative Research Initiatives of the Korean Ministry of Science and Technology.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Condensed Matter Physics
- Physics and Astronomy (miscellaneous)
- Metals and Alloys