Nickel titanium (NiTi) is a shape memory alloy also commonly referred to by its trade name, Nitinol (Nickel Titanium Naval Ordnance Laboratory). Above its transformation temperature, Nitinol is superelastic, able to withstand a large amount of deformation when a load is applied and return to its original shape when the load is removed. Below its transformation temperature, it displays the shape memory effect. When it is deformed it will remain in that shape until heated above its transformation temperature, at which time it will return to its original shape. William Buehler discovered this along with Frederick Wang during research at the Naval Ordnance Laboratory. (wikipedia)