Field-activated combustion synthesis in the Nb-Si system

The activation of self-propagating combustion reactions in the Nb-Si system was investigated using an electric field. Self-sustaining combustion in elemental reactants with compositions corresponding to Nb5Si3 can be initiated only when the imposed field is above a threshold value of 7.4 V cm−1. The mode of wave propogation and the nature of the product depended on the magnitude of the field. Under steady-state wave propagation, the product contained the high temperature (β) and low temperature (α) modifications of Nb5Si3. The relative concentration of these phases showed a dependence on the applied field and on the relative density of the reactant compacts. The effect of Nb particle size on the synthesis of Nb5Si3 was investigated and the feasibility of the synthesis of Nb/silicide composites was demonstrated.