Tailoring the Reaction Path: External Crack Initiation in Reactive Al/Ni Multilayers

The influence of intentionally externally induced cracks in reactive Al/Ni multilayer systems is investigated. These cracks affect the reaction dynamics and enable tailoring of the reaction path and the overall velocity of the reaction front. The influence of layer variations onto mechanical crack formation and resulting reaction behavior are investigated. High-speed camera imaging shows the meandering propagation of the reaction front along the crack paths. Therefore, the mechanical cracking process significantly changes the total velocity of the reaction front and thus offers a possibility to control the self-propagating high-temperature synthesis process. It is shown that the phase formation remains unaffected despite the applied strains and cracks. This favorable stability in phase formation ensures predictability and provides insight into the adaptation of RMS for precision applications in joints. The results expand the understanding of mechanical cracking as a tool to influence high-temperature synthesis in reactive multilayer coatings and provide an opportunity to expand the range of applications. This study investigates intentionally external induced cracks in reactive Al/Ni multilayers, influencing reaction dynamics and front velocity. Despite strain and cracks, phase formation remains stable, ensuring predictability for precise joining applications. The findings extend understanding of mechanical cracking in controlling high-temperature synthesis, providing insights for materials science and engineering applications.image (c) 2024 WILEY-VCH GmbH