摘要：Each conventional alloy has its own specific compositions but the compositional origin is largely unknown due to our insufficient understanding about chemical shortrange ordering in the alloy,in particular,in the solid-solution *** the present paper,the compositions of metallic alloys are discussed and formulated,by unveiling the basic moleculelike structural units in solid *** oscillation theory,which describes the partial charge screening behavior in solid solutions,and henceforth the origin of short-range ordering,is applied to pin down the ideal chemical compositions of conventional metallic *** propose that,at a specific composition,atoms self-assemble into an ideally ordered structure consisting of atoms residing in the nearestneighbor shell(denoted as cluster)plus those in the next outer shell(denoted as glue atoms),which can be formulated as[cluster](glue atoms).This simplified version of short-rangeorder structure represents the smallest charge-neutral and mean-density zone(termed as“chemical units”)and can be regarded as the‘molecules’of solid ***,the chemical units and the corresponding molecule-like formulas for face-centered-cubic(FCC),hexagonal close-packed(HCP),and body-centered cubic(BCC)structures are analyzed and equations are obtained to identify the chemical formulas for FCC solid *** instance,well-knownα-brass Cu-30 Zn alloy is formulated as[Zn-Cu_(12)]*** of aluminum alloys,superalloys and stainless steels are also illustrated,demonstrating the versatility of the present model to interpret chemically complex alloys.