Architecture-independent reactivity tuning of Ni/Al multilayers by solid solution alloying

Abstract

Reactive multilayers are energetic nanostructures that are able to deliver a large amount of chemical energy via an exothermic reaction. These materials have been a subject of growing interest as they have been shown to provide effective local heat delivery for microscale propulsion or biological hazard neutralization. Nonetheless, their use as heat sources remains narrow because of the limits in tuning their intrinsic reactivity without altering their architecture. Here, we propose a method for the adjustment of reaction kinetics in Ni/Al multilayers via solid solution alloying with elements having different reactivities toward aluminum. Nickel layers were alloyed with copper and platinum, resulting in strong modification of the properties of the heat front, temperature, and propagation velocity, while at the same time leaving the multilayer architecture unaltered. This effect hails from a shift in the rate limiting mechanism during intermixing of the reacting species that promotes the propagation of the reaction. The results of this study will expand the field of application of reactive multilayers as integrated heat sources, thermal batteries, or microheaters.