The Pentagon has quietly been working on a new arsenal of advanced weaponry that replaces metal casings with ''reactive materials,'' normally harmless matter that combines to release explosive amounts of energy on impact, tearing targets apart with violent fury. In development for more than 30 years, the research is beginning to bear fruit, and may soon spawn more powerful bombs, warheads that tear apart stone and concrete, (Snip) grenades that can swat rockets or mortar rounds out of the sky like flies.
Reactive materials are combinations of materials that are normally stable, but, when subjected to sudden shock -- such as striking a target -- release a large amount of energy. Depending on the composition and warhead design, the energy can be released as heat, a blast or a combination of the two. Unlike conventional explosives, RMs cannot be set off by fuses. Technically, they are classified as flammable solids, and they are less hazardous to transport and store than explosives.
While they're more energetic than explosives, RMs are not intended to be a substitute. Instead, they will replace warhead components normally made of metal.
http://www.wired.com/politics/security/news/2008/05/reactive_revolutions
