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Self-propagating exothermic reactions in multilayer films/foils (MF) are receiving attention as novel heat sources due to their high potential for joining temperature sensitive components such as microelectronics and amorphous metals. Typically consisting of hundreds of alternating metallic layers in the nanometer range, MF structures can be produced by plasma-assisted physical vapor deposition (PVD) techniques, such as magnetron sputtering, and have recently been reported in the Al-Ni and Al-Ti systems. However, the application of MF’s as heat sources is limited due to the uncontrolled heat generation rate.
In this study, we investigated the influence of aluminum oxide layers between aluminum and nickel layers, on the reaction kinetics of multilayer stacks. Heat and mass transfer in the presence of alumina interlayers with various geometries, as well as across alumina layers with hexagonally packed nanoscale pores were modeled using numerical methods (3D finite differences). The computational results were compared with experimental results from previous studies. The results show that the reaction rate is a function of the thickness and geometry of the alumina layer and the pore dimensions therefore can be controlled by design parameters.
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