Cluster Lines in Ternary Alloy Phase Diagrams

摘要

This paper points out a general composition rule, i.e. cluster line criterion, for ternary alloy phases. The cluster line refers to a straight composition line linking a specific binary dense-packing cluster to the third element in a ternary alloy phase diagram. Quasicrystals and amorphous phases as well as certain crystalline alloy phases satisfy the cluster line rule. Al-based ternary quasicrystals are taken as examples to show how the cluster line rule applies. Actually an Al-based ternary quasicrystal is always located at the intersection of two cluster lines in a ternary phase diagram. Ternary bulk amorphous alloys are also known to satisfy similar cluster line rule so that their structure can be regarded as being composed of a binary basic cluster plus glue atoms. Applications of such an approach have been proven successful in deciphering compositions of different ternary crystalline compounds.