Determination of local atomic configurations for binary substitutional alloys

A method is described whereby the complete distribution of first-nearest-neighbor atomic configurations can be determined from experimental short-range order coefficients for binary substitutional f.c.c. alloys. The process involves the computer simulation of the structure represented by the experimental α_i by a Gehlen–Cohen-type procedure, followed by the classification of each atom of a given species in the model as one of the 144 crystallographically distinct nearest-neighbor types. These simulation and searching procedures are then used to demonstrate the consistency of the information one can expect to obtain from a given set of α_i by `close fitting' to different numbers of coordination shells. It is shown, for example, that a six-shell close fit to a selected set of α_i can yield a solution with a mean relative deviation of about five per cent for the nearest-neighbor configuration concentrations.