Cluster formulae for alloy phases

Composition formulae for alloy phases are developed using first-neighbour coordination polyhedra plus their connections. The resultant cluster formulae [cluster](glue atom)(x), similar to molecular formulae for chemicals, contain key structural and composition information on the alloy phases. As examples, Al-Ni-Zr alloy phases are analysed with the objective of revealing cluster formula properties such as the principal cluster, the cluster phase and the definition of complex alloy phases.