Engineers, inspired by nature, created what is claimed to be the first manufactured non-cuttable material. The idea for the new lightweight material came from the tough cellular skin of the grapefruit and the fracture-resistant shells of the abalone sea creature.
Called Proteus, the material is made from alumina ceramic spheres encased in a cellular aluminum metallic foam structure and works by turning back the force of a cutting tool on itself. In tests, Proteus could not be cut by angle grinders, drills, or high-pressure water jets. The architected material is both highly deformable and ultra-resistant to dynamic point loads.
The bio-inspired metallic cellular structure has only 15% steel density. The architecture derives its extreme hardness from the local resonance between the embedded ceramics in a flexible cellular matrix and the attacking tool, which produces high-frequency vibrations at the interface. When cut with an angle grinder or drill, the interlocking vibrational connection created by the ceramic spheres inside the casing blunts the cutting disc or drill bit. The ceramics also fragment into fine particles that fill the cellular structure of the material and harden as the speed of the cutting tool is increased
Essentially, cutting the material is like cutting through jelly filled with nuggets — after getting through the jelly and hitting the nuggets, the material vibrates in such a way that it destroys the cutting disc or drill bit. Water jets are also ineffective because the curved surfaces of the ceramic spheres widen the jet to substantially reduce its speed and weaken its cutting capacity.
Proteus could be used to make bike locks, lightweight armor, and in protective equipment for people who work with cutting tools.