FROM FRANK-KASPER PHASES TO THE ICOSAHEDRAL QUASICRYSTAL

Abstract
This is a resume of works carried out recently on the structure of icosahedral quasicrystal. Part I deals with a microdomain structure of several pentagonal Frank-Kasper phases displaying 5 symmetry but no ordinary translation order, a structure quite close to the two dimensional quasicrystal. Part II describes how a new icosahedral phase with the point symmetry m35 was found in NiTiV alloys by rapid solidification of alloys with a structure of or akin to a pentagonal Frank-Kasper phase. Part III discusses the structure models of the two- and three-dimensional quasicrystals derived from their close structure relationship, especially the rhombohedral MgCu₂ unit, to the pentagonal Frank-Kasper phases.