The role of transitional phase formation during ignition of reactive multilayers
The ignition processes of sputter-deposited reactive Ru/Al multilayers were studied, measuring temperatures and calculating activation energy of ignition for bilayer thicknesses between 22 nm and 222 nm. Microstructural investigations of a partially reacted sample show that the grain boundary-dominated formation of a transitional Al6Ru phase plays an important role during ignition by triggering a more exothermic formation of the final product phase. A model of hot-plate ignition is proposed, based and tested on a designed three-component Ru/Al/Cu multilayer showing a strongly reduced ignition temperature versus its binary counterpart. The results demonstrate the role of transitional phase formation during ignition and provide a further means to modify ignition temperatures of reactive systems.
