The equation of calculating Faber-Ziman partial structure factors for models of binary alloys is derived from Debye equation. The SFeB(Q) and SNiB(Q) of models for Fe83B17 and Ni64B36 metallic glasses are calculated, and compared with the experimental results and the partial scattering intensities IFeB(Q) and INiB(Q) The partial structure factors of model for Hg2Na liquid alloy are also calculated, and extrapolated to the long wavelength limit. Finally, the behavior of the total structure factors near the long wavelength limit for alloys, which have chemical short range order, is discussed.