Abstract
Intermetallic compounds with compositions in the vicinity of Al0·6 (Cu, Zn), (Li, Mg)0·3, namely the so-called R, Z, C and τ phases, have been selected for structural studies because of their presumed relation with the Al-Cu-Li quasicrystal. Neutron diffraction data strongly suggest unicity for short- and medium-range arrangements in these phases. Transmission electron microscopy confirms the point and allows detailed modelling, based on connections of atomic clusters having icosahedral symmetries and taken from the crystallographic structure of the b.c.c. R-phase.