Reactive materials, characterized by the exothermic response of two or more phases to an external stimulus, depend on the transport of mass and heat, along with the release of the latter. Consequently, the micro- and nanoscale morphology of the reactant phases plays a pivotal role. Typically represented as sputtered multilayer stacks, where bilayer thickness is a key design parameter, controlled deviations from an ideally flat binary layer stacking are challenging to achieve by altering the deposition process alone.

This study introduces a novel approach to modify the micro- and nanoscale morphology of magnetron-sputtered Ni/Al multilayers by employing micrometer periodic surface patterning on the growth substrate. Line structures with varying periodicities were applied to thin copper substrates using picosecond Direct Laser Interference Patterning (DLIP) on an area of several cm². Subsequent electropolishing was employed to eliminate sharp asperities, resulting in nearly ideal, smooth sinusoidal surface profiles. Following the deposition of the Ni/Al multilayer stack, distinct alterations in layer morphology were observed, influenced by the structure's period and depth.

During deposition, shadowing effects produced pores at specific locations within the multilayer. This well-defined large-scale distribution of defects facilitates a quantitative understanding of how pores impede heat and mass transport, thereby slowing down the Self-Propagating High-Temperature Synthesis (SHS) reaction. Furthermore, the substrate pretreatment induced local changes in the interface roughness between individual layers of the multilayer stack, along with a periodic modulation of bilayer thickness.