Aluminum-based metastable intermixed composites (MICs): structural control for desired reactivity

Aluminum (Al)-based metastable intermixed composites (MICs) are a promising class of energetic materials widely used in solid rocket propellants, pyrotechnic formulations, and high explosives. Particular attention is currently being paid to the development of methods for the fabrication of such composites, investigating the impact of the processing parameters on their morphological and structural characteristics, which, in turn, determine their thermal reactivity, sensitivity, and combustion behavior. This review provides a comprehensive assessment of current achievements in the field of Al-containing energetic composites, with an emphasis on methods for controlling their architecture from traditional Al/M_xO_y systems to modified MICs, using carbon nanomaterials, fluorine-containing components, and energetic polymers as additives. The mutual relationships among structure, thermal properties, and combustion mechanisms, including reaction kinetics, flame propagation, and the formation of high-temperature condensed-phase products, are fully examined and compared. Particular attention is paid to the effects of morphology and interfacial contacts on the combustion efficiency, using the example of composites with identical ingredients but different architecture. New strategies for improving energy efficiency with reduced sensitivity and minimized negative environmental impact are also discussed. The presented information on these novel MICs is expected to broaden the understanding of the structure–property relationships for the Al-based energetic composites and serve as a basis for further development of new generations of metal-based composite fuels with tailored performance.