Three sandwich layers of an Si/Me/Si structure, where Me = Al, Ni or Cr, with a total thickness between 116 and 170 nm were sputter deposited onto smooth silicon (111) substrates. Reactions of the metals with amorphous silicon thin films were activated in a differential scanning calorimeter, at a heating rate of 40 degrees C min(-1), between room temperature and different higher temperatures. Auger electron spectroscopy depth profiling of as-deposited and dynamically heat-treated samples enables the observation of the movment of Si-Me interfaces and the identification of the main migrating elements in the early stage of the reaction. Formations of different reaction products are in agreement with the phases predicted by the effective heat of formation model after Pretorius.