The influence of premixed interlayers on the reaction propagation in Al–Ni multilayers —An MD approach

Abstract

The existence of a premixed interlayer has a direct influence on the reaction kinetics in reactive multilayers. In this study, molecular dynamics simulations are used as a tool to study the influence of premixed interlayers on the front propagation and diffusion in Al–Ni multilayers. For this, premixed interlayers with different, namely, homogeneous, gradient, and s-shaped profiles are studied. Comparison with existing experimental results further increases the understanding of the nature and importance of the premixed interlayer. Moreover, this study shows how this premixed interlayer can be used as a reaction barrier to decrease and thus control the front propagation velocity. Diffusion of Al and Ni atoms through the interlayer takes place, even if the interlayer has partially crystallized, which means the front propagation is driven by a combination of diffusion and crystallization of the interlayer. Furthermore, it is shown that the heat of crystallization of amorphous AlNi to B2-AlNi alone is high enough for a self-propagating reaction to occur.