Effects of multilayer arrangement in ternary reactive film on self-propagating reaction properties

The effects of multilayer designs in ternary films on self-propagating exothermic reaction properties were reported. The magnetron sputtered deposited ternary reactive films with two different multilayer arrangements of Ti/Si/Ti/Al and Si/Ti/Al/Si with the identical bilayer of 29 ± 5 nm and total thickness of 6 μm were investigated. The reaction properties in terms of reaction heat, temperature and reaction velocity were characterized for these two types of multilayer constructions. The reaction heat was calculated by using the thermodynamic simulation. As-deposited and reacted foils were characterized by using electron microscopes. After an electric ignition, the exothermic reaction front propagates in the films. The propagation velocity and temperature were measured by using a high speed camera and a two-color pyrometer. Reaction products were analyzed by means of X-ray diffraction (XRD) analysis. The steady state reaction fronts propagate through Ti/Si/Ti/Al films with the reaction velocity of 9.1 ± 2 m/s and the maximum reaction temperature of 1768 ± 41 °C. Moreover, both steady state and unsteady propagation modes were observed in Si/Ti/Al/Si reactive foil. This film shows a maximum reaction velocity of 2.7 ± 0.8 m/s. Compared to this film, Ti/Si/Ti/Al films exhibit higher reaction temperature and propagation velocity. Here, experimental results suggest the dependency of the reaction properties on the multilayer arrangement. Although both ternary films have similar reactant types and morphology, different reactant interfaces introduce the distinct interfacial reactions and local atomic mixing rates, which influence on the reaction characteristics. This research also shows a new opportunity to design nanoscale reactive films with different multilayer arrangements to control reaction propagation besides existing technology.