Rather than talking about explosives, David Hambling explains (in Swarm Troopers), researchers tend to refer to “energetic materials”:
It is an umbrella term covering everything from detonators to incendiaries to rocket fuel.
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In the field of energetic materials, Reactive Materials or RMs have shown great potential for developing weapons far more effective than conventional high explosives. RMs typically consist of a material such as Teflon mixed with metal powder.
Reactive materials also make highly effective shrapnel. Normally, shrapnel is made of steel or similar material; shrapnel fragments are like miniature bullets. But reactive material shrapnel is explosive: the material can be engineered so that it starts releasing energy when it impacts an object. This makes RMs effective as anti-aircraft and antimissile warheads, as adding a little explosive power makes them much more lethal. According to one estimate, they are five times as effective against aircraft and similar targets as conventional shrapnel. They would be similarly effective as an anti-personnel weapon.
During WWII, a new type of weapon was developed known as thermite. This is a simple mixture of metal and metal oxide powder, like iron oxide and aluminum, but it burns at extremely high temperature. Impossible to extinguish once started, thermite can melt through steel plate, and commandoes used thermite charges to disable guns and heavy machinery. Reactive materials can do better than that.
Energetic Materials & Products Inc. of Round Rock, Texas, has been involved in the Air Forces’ micro-scale ordnance efforts and used the technology in a spin-off called the Tec Torch or Metal Vapor Torch. This flashlight-sized device blasts out a flame jet that cuts through metal like a hot knife through butter, slicing through a half-inch steel bar in less than a second. It has been designed as a breaching tool for police and others who need to cut through bolts, chains, and padlocks at high speed. The Tec Torch is based on reactive material technology with solid fuel and oxidizer, and is cheaper, lighter, and more compact than the traditional oxyacetylene cutting torch.
Each fuel cartridge weighs a couple of ounces and contains precisely graded particles of magnesium, aluminum, and copper oxide. This resulting flame jet burns at over three thousand degrees centigrade and has a speed of over two thousand meters a second. A rectangular carbon fiber nozzle shapes the jet into a flat blade for cutting through bars. The jet has higher energy density than a gas flame, and the cutting action is a combination of heat and abrasion by particles of metal oxide.
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A drone perching on a structure could use its own version of the Tec Torch to slice through a vital component, such as power or communication lines — or the cables supporting a suspension bridge.
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This type of technology could also be effective at puncturing pipelines, and fuel and chemical storage tanks.
Um, thermite, aluminum powder and iron oxide, has been known for a lot longer than the 1940s. The thermite reaction was discovered in 1895. The general category (reactive metal powders and metal oxides) has been expanded since then, and no question thermite grenades were used in WW2. Regardless, this source, Hambling, should be regarded as questionable (assuming he’s accurately quoted) since this dating of thermite is easily disproved.
Those cutting rods have been commercially available for decades. Among other uses, locksmiths use them to cut open safes.