The variation of the atomic scattering factor near the X‐ray absorption edge of an element can be an important tool for determining the distribution of that element in any sample. For defining experimentally the possibilities of anomalous small‐angle X‐ray scattering (ASAXS) in metallurgy, three compositions of a phase‐separated aluminium‐zinc alloy have been studied at different energies below the Zn‐absorption edge, using a synchrotron radiation source. In order to test the reliability of these measurements and of the data treatment, the variation off′, the real part of the scattering factor, has been measured with a precision comparable to that of more direct