A shape-memory alloy comprised of nickel and titanium is called nitinol. Depending on the changing temperatures, it undergoes a phase transformational shift in its crystal structure. Its shape changes as it cools from its high-temperature austenite form to its low-temperature martensite form. Nitinol Shape Memory Sheet is used in a variety of industries. The thermal and electrical actuators are first utilized as autofocus actuators in action cameras or as a sensor and actuators in thermal valves for fluidics. In biomedicine, this substance is also widely used. Since nitinol is very biocompatible, it can be used in medical devices such as orthopedic implants, catheters, braces, wires for orthodontic treatment, and neurovascular therapies like stroke thrombolysis. Stents made from it play a big part in medicine as well. With body warmth, it expands back to its original shape after being put into an artery or vein, improving blood flow. Superelastic nitinol is also utilized in structural engineering to produce bridges and other structures. When nitinol wires are incorporated into concrete during construction, these wires can detect cracks and highlight them at macro sizes.
Applications
- Antenna for mobile phones
- Drones and toys
- frames for eyeglasses
- dental wires, stents, and other gadgets and medical equipment.
THE SHAPE MEMORY EFFECT
The shape memory effect is most frequently demonstrated by deforming a piece of metal, such as by tightly coiling a piece of straight wire, and then entirely undoing the deformation by heating the metal, such as by dipping it in hot water. The metal instantly "remembers" its previous shape as it is heated and instantly assumes the shape of a straight wire. The material experiences a change in the crystal structure as it is cooled or heated past its typical transformation temperature, which results in the shape memory effect.
From an ordered cubic crystal form (austenite) above its transformation temperature to a monoclinic crystal phase below the transformation temperature, the NiTi alloys' crystal structure changes (martensite).
