The shape memory alloy is named after its place of discovery, the research facility: Nickel Titanium Naval Ordnance Laboratory. When the material is deformed in a cool state, it returns to its original shape after heating.
The distinctive feature of nitinol is characterized by this reversible solid phase change, known as martensitic transformation. The alloy material forms a crystalline structure capable of changing from one form to another. Temperature change and/or strain induce this transformation.
Above its transformation temperature, nitinol is superelastic and thus can resist some degree of deformation when a load is applied. Once the load is removed, it returns to its original shape. Below its transformation temperature, Nitinol is subject to the thermal shape memory effect. After deformation, it will remain in this state until it is heated above the transformation temperature so that it returns to its original shape.