Structure of icosahedral clusters in cubicAl5.6Li2.9Cu

The icosahedral and related crystal approximant phases in Ti-Zr-Ni alloys

“…Two crystal structures are of particular importance for the study of quasicrystals, the u-(Al-Mn-Si) phase an almost b.c.c. phase (Pm3 with a0-12.68A), which is the approximant for many A13d t In final form 21 February 1994. transition-metal i-phases (Elser andHenley 1985, Guyot, Audier andLequette 1986) and the Bergman phase (Im3 with a0 = 13.1 8). related to i-phase formation in Mg-Al-Zn and Al-Cu-Li alloys (Guryan, Stephens, Goldman and Gayle 1988).…”

“…phase (Pm3 with a0-12.68A), which is the approximant for many A13d t In final form 21 February 1994. transition-metal i-phases (Elser andHenley 1985, Guyot, Audier andLequette 1986) and the Bergman phase (Im3 with a0 = 13.1 8). related to i-phase formation in Mg-Al-Zn and Al-Cu-Li alloys (Guryan, Stephens, Goldman and Gayle 1988). While TizNi was first proposed as the appropriate crystal approximant for the Ti-based i-phases, it is now known that the structures of Ti-based quasicrystals are related to a true b.c.c.…”

Interpretation of the Hume-Rothery rule in quasicrystals and their approximants

“…The atomic structure of c-brass is reproduced from the table compiled by Pearson's handbook [11], whereas those for the Al 30 Mg 40 Zn 30 and Al-Li-Cu 1/1-1/1-1/1 approximants from Mizutani et al [12] and Guryan et al [13], respectively. There exists chemical disorder in the occupation of the cluster sites.…”

Cluster-disordered glue model and role of glue atoms in the icosahedral quasicrystalline structure

“…These have shown that Al atom at the central site gives the most stable binding. The atomic positions in the ideal icosahedral symmetry and crystal approximant positions are as given in the literature [17,18]. The crystal approximant has a 4-shell cluster around the central site (A).…”