What happens as the interface of the initial virgin couple of materials at the very beginning of reactive diffusion?-composition changes, vacancy fluxes, stress generation, nucleation of intermediate phases and movement of newly born interphase interfaces. All these processes are closely interrelated and lead to formation and growth of certain phases andto suppression of others. We present the review of phase competition theory taking into account some of aforementioned factors and application of this theory to the description of solid state amorphizing reactions.

Nontraditional methods of producing the amorphous metallic alloys based on the solid state arnorphizing reactions have been developed during the last decade - amorphizing by diffusion, by ball milling, spontaneous vitrification and others. The main problem here from the theoretical point of view is to explain why doesthe metastable amorphous phase appears instead of stable intermediate phases with corresponding composition.