Influence of Additional Intermediate Thick Al Layers on the Reaction Propagation and Heat Flow of Al/Ni Reactive Multilayers

Abstract

This study investigates the effects of sputtering and electron beam evaporation (e-beam) on the microstructure and reactive properties of Al/Ni reactive multilayers (RMLs). The intermixing zone, a critical factor influencing reaction kinetics, is characterized using high-resolution transmission electron microscopy and found to be consistently 3 nm for both fabrication methods. Differential scanning calorimetry reveals that e-beam samples, with thicker Al layers, exhibit slightly higher total molar enthalpy and maintain high reaction temperatures despite reduced reaction velocities in comparison to sputtered samples. X-ray diffraction confirms the formation of both Al3Ni2 and AlNi phases in the e-beam samples. These findings indicate that while thicker bilayer structures reduce reaction velocity, they keep thermal output and mitigate the impact of intermixing zones, leading to similar total molar enthalpy. This analysis underscores the significance of deposition technique and bilayer thickness in optimizing the performance of Al/Ni RML, offering the possibility to establish different phase formations in thicker RML. It advances the control over the reactive properties of RMLs in their applications, for example, reactive bonding.