These unique metals made from combinations of two or more elements, exhibit hardness and elasticity properties that change radically at distinct temperatures. First observed in 1932 in a Gold-Cadmium alloy (expensive and toxic), interest and research greatly expanded upon the discovery of a Nickel-Titanium (lower cost and non-toxic) alloy in the 1960's.
After alloying and basic processing, Muscle Wires® can be formed into a shape (for example, a coil spring), and then set to that shape by a high heat treatment. When cooled, they may be bent, stretched or deformed (within limits) and then with subsequent moderate heating (well below the heat setting temperature), they can recover some or all of the deformation - the move when heated!
Muscle Wires® have found use in everything from space missions (Clementine, Pathfinder and many more) to floral arrangement (animated butterflies, dragonflies and fairys), from arterial stents for restoring blood flow to clogged arteries, to actuators for miniature robots. And cell phone antennas, orthodontic braces and even eyeglasses use Muscle Wires® wires for their extreme flexibility.