How do they make Nitinol superelastic?
When the metal is very close to the transition temperature, applying force is enough to change some atoms of the metal from one state to the other, bending the wire. When you let go (force is removed), the metal goes back to the rigid state, remembering its shape. Relevance to our lives : Nitinol’s shape memory has found use in many appliances as a switch that responds to either heat or electric current. Orthodontists use Nitinol as the wires for braces. In a person’s mouth, the Nitinol warms, changes shape, and pushes on the teeth. This is less painful than steel wires, and allows for more time between orthodontist appointments. Super elasticity gives us “unbreakable” eye glasses frames and fish hooks, because the metal bends rather than breaking.
