Influence of vacancy defect concentration on the combustion of reactive Ni/Al nanolaminates

Self-propagating reactions in Ni/Al nanolaminates have been widely studied for their high combustion temperatures surpassing 1900 K and rapid combustion wave speeds exceeding 10 m/s. These combustion characteristics have motivated unique industrial applications, such as soldering of electrical components, and possible military applications. Unfortunately, there is a limited understanding of the effect of lattice defects on combustion characteristics. This work explores the effect of vacancy concentration on the combustion rate and peak temperature of reactive Ni/Al nanolaminates. Increasing vacancy concentration increases both reaction rates and peak reaction temperatures. For the reaction rate, vacancy concentration effects are shown to be interdependent with bilayer thickness, initial temperature, and hydrostatic pressure. The effects on reaction peak temperature are independent of these other system parameters. A new method for mapping vacancy and composition profiles is presented to demonstrate the formation and migration of vacancies during the self-propagating reaction.