The solid‐state reaction between a nickel (7 at. % gold) film and a silicon substrate at temperature lower than the gold‐silicon eutectic temperature (370 °C) is examined by transmission and scanning electron microscopy and by Rutherford backscattering spectrometry. Epitaxial NiSi and preferentially oriented Ni2Si are present and gold precipitation occurs at the inner interface. This gold precipitation leads to a peculiar backscattering spectrum which is analyzed taking into account morphological information. The driving forces leading to gold redistribution are interpreted in terms of surface energies and chemical interactions with silicon. ©1995 American Institute of Physics.