Reactive materials (RM) are a new class of materials that are currently being investigated by the Office of Naval Research and others as a means to increase the lethality of direct-hit or fragmentation warheads.
Reactive materials usually are thermite-like pyrotechnic compositions of two or more non explosive solid materials, which stay inert and do not react with each other until subjected to a sufficiently strong mechanical, electrical or laser stimulus, after which they undergo fast burning or explosion with release of high amount of chemical energy in addition to their kinetic energy.
Fragments or projectiles made from such materials have therefore greater damaging effect than inert ones, with expected lethality increase up to 500%.The material classes under investigation of reactive materials such as thermites, intermetallic compounds, metal-polymer mixtures (e.g. Magnesium/Teflon/Viton-like) and metastable intermolecular composites (MIC), matrix materials, and hydrides.
These materials have to be strong enough to act as a structural components, to penetrate the target and be sufficiently stable to survive handling and launch, and sufficiently unstable to reliably ignite on impact.The mixtures under investigation include one or more finely powdered (down to nanoparticle size) metalloids or other metals like aluminium, magnesium, zirconium, titanium, tungsten, tantalum, or hafnium, with one or more oxidizers as teflon or other fluoropolymer, pressed or bonded by other method to a compact, high-density mass. To achieve a suitable reaction rate and insensitivity to impact, friction, and electrostatic discharge, fuel particles have sizes usually between one to two fifty µm.
A standard composition is aluminium-teflon (Al-PTFE) is a good reactive material.Metals which can form intermetallic compounds by an exothermic reaction are another class of candidate materials in reactive metals. Laminate of thin alternating layers of aluminium and nickel, commercially available a NanoFoil is an example of that materiels.The Reactive materiel weapons under development include an active protection system defensive grenade for interception of incoming missiles or grenades and detonation of them in a safe distance, and the BattleAxe warhead that covers a wide area with Reactive materiel fragments with devastating results to soft targets, while the unexploded fragments left behind having very low lethality in comparison with conventional cluster bomb leftovers.
Under research reactive materials that have high mechanical strength, high density, and high energy density, and that are capable of rapid conversion from a consolidated structural material to fine powder with large surface area, dispersed and then ignited to produce a massive thermobaric blast.