The effect of mechanical activation on highly exothermic powder mixtures

The formation of MoSi2 by ball milling a mixture of Mo and Si powders can take place according to a self-propagating reaction. The mechanical activation that leads to the initiation of this process, is investigated by structural and thermal analysis of samples milled for periods shorter than the ignition time. It is shown that the ignition temperature does not change substantially upon milling. The main change is an increase of the interface area and, consequently, transformation of a larger fraction of the reactants when solid state reaction is initiated by heating.