Metallic glasses atomic packing

Crystal approximants. Several crystalline phases contain more or less closely packed atomic assemblies (polyhedra, clusters) which have been considered fundamental constituents of several quasicrystals, metal glasses and liquids. Such crystalline phases (crystal approximants), as reported in the previous paragraph, are often observed in the same (or similar) systems, as those corresponding to the formation of quasicrystals and under similar preparation conditions. Crystalline phases closely related to the quasicrystals (containing similar building blocks) have generally complex structures as approximants to the ico-quasicrystals we may, for instance, mention the Frank-Kasper phases (previously described in 3.9.3.1). 

Metals are closely packed arrangements of similar atoms that share electrons rather loosely. Metals are often lustrous or reflective. They are ductile and may be bent without breaking. They are often excellent conductors of heat and electficity, in contrast to crystals or glasses that usually are poor conductors. 

Miracle, D. B. (2004b) A structural model for metallic glasses, Nature Mater., 3, 697-702. Miracle, D. B. (2006) The efficient cluster packing model - an atomic structural model for metallic glasses, Acta Mater., 54, 4317—4336. 

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