The methods of X ray diffraction, Mössbauer spectroscopy, IR spectroscopy, and laser diffracto metry are employed to study the changes in the structure and phase transformations that accompany mechanical alloying of Si and 57 Fe used in an atomic ratio of 99 : 1. It is established that the process comprises the development of a nanocrystalline state of Si with crystallite sizes smaller than 10 nm; the formation of an amorphous phase of Si at particle surfaces and in near boundary distorted zones of interfaces in Si nanostruc ture; the penetration of 57 Fe atoms along grain boundaries; and the formation of Si-Fe clusters, the local environment of Fe atoms in which is typical of a deformed α FeSi 2 phase, with these clusters being located in the interfaces.