Tailoring self-propagating reaction dynamics in Ni/Al reactive multilayer foils via laser micromachining

Reactive multilayer foils (RMFs) offer highly localized heat generation through self-propagating exothermic reactions, making them attractive for advanced bonding applications. However, controlling the spatial and temporal distribution of heat remains a challenge. This study investigates the use of femtosecond laser micromachining to tailor the reaction dynamics of commercial Ni/Al reactive multilayer foils through the introduction of geometrical patterns. Four designs were chosen to impose distinct constraints on the reaction front. High-speed imaging combined with a custom image analysis algorithm enabled frame-by-frame tracking of local velocity fields. The results show that laser structuring can significantly alter reaction dynamics and propagation behavior by introducing front redirection, splitting and merging, leading to controlled delays and spatially localized acceleration zones. These effects enable modulation of global reaction times and localized energy release without suppressing or disrupting continuous front propagation. The findings demonstrate that laser structuring is an effective tool for tailoring heat delivery in RMF-based systems, with direct relevance to advanced bonding processes and thermally sensitive materials.