Contribution of a hard-spheres packing model to the determination of binary alloy phase diagrams

Attempts to explain the stoichiometrics of intermetallic compounds in binary phase diagrams are described. The model presented yields compound compositions which are simple rational numbers and is expected to be useful for work on intermetallic phase diagrams. The occurrence of compounds in 10 binary systems (Si-Hf, Co-Y, Hg-Sr, Rh-Gd, Au-Sm, Hg-Ca, Pt-In, Au-In, Fe-Al, and Pd-Ti) is compared with the results of the calculations. It is concluded that a considerable number of compounds occurring in these systems is justified by the proposed hard-spheres packing condition. The dependence of the efficiency of the method on the radius ratio and on the compound components is indicated.