Exothermic reactions in cold-rolled Ni/Al reactive multilayer foils

Exothermic reactions in cold-rolled Ni/Al reactive multilayer foils were investigated in this study. A two-stage reaction process was observed in the self-propagating reactions in the cold-rolled foils that were ignited by a point-source flame. Foils taken out of the flame after completing the first stage of the reaction process were compared to those allowed to complete both stages. Differences in the phase-evolution sequence from the two types of foils were studied by differential scanning calorimetry (DSC), using slow and controlled heating of the samples. Several exothermic peaks could be identified from the DSC thermograms for both types of foils. Using the DSC, both the as-cold-rolled and partially reacted foils were heated to each peak temperature to identify the reaction product associated with each peak. X-ray diffraction and scanning electron microscopy analyses showed that the first two peaks corresponded to the formation of Al₃Ni, while the third peak corresponded to the formation of AlNi.