THE ATOMIC-STRUCTURE OF THE DECAGONAL PHASE AND ITS APPROXIMANTS AS RANDOM COINCIDENCE NETWORKS

It is shown that the decahedral recursive model (DRM) explains at atom ic level the structure of the decagonal (D) phase and associated appro ximant structures as random coincidence networks (RCNs), random packin gs of clusters satisfying DRM energy minimizing rules. RCNS are degene rate random tilings that become quasiperiodic when entropic disorder i s maximized at high temperature through phason flips requiring small a tomic movements. Such phason flips can change the relative ratio and g eometry of tiles, making transformations between systems using differe nt tile sets possible. Electron microscopic observations for AlCuCoSi, AlCuFeCr, AlCoCu and AlPdMn systems are reproduced, including the obs erved Fibonacci sequenced lines in the former.