On the Physicochemical Mechanism of the Influence of Preliminary Mechanical Activation on Self-Propagating High-Temperature Synthesis

The analysis of physicochemical mechanism of the influence of mechanical activation (MA) of a charge mixture on the subsequent self-propagating high-temperature synthesis (SHS) of intermetallic compounds is performed. Numerical estimates have revealed an insignificant role of the energy stored in solid reactants due to cold work during MA. The characteristic time of relaxation of non-equilibrium vacancies, which were generated in metals by MA, during heating in the SHS wave is estimated, and their insignificant influence on the reaction kinetics at high temperatures is demonstrated. It is shown that a strong effect of preliminary MA on SHS can be attributed only to deformation-enhanced solid-state diffusion during MA, which can lead to the formation of a supersaturated solid solution and thus affect the conditions for nucleation of a product phase (intermetallic compound) upon heating.