Nitinol is a unique alloy made of nickel and titanium that exhibits a "shape-memory effect". This means that when heated, it can reform its original shape after being bent or deformed. The alloy's atomic structure is composed of crystallites that change their arrangement in response to temperature changes, allowing it to remember its original shape. Nitinol also exhibits super elasticity, where it can be severely deformed and then return to its original shape. These properties make nitinol useful in various applications, such as in medical devices (e.g. stents), high-end products (e.g. eyeglasses), and even in engine design.
Here are the key facts extracted from the text:
1. The spring is made of nitinol wire, which comes from the elements nickel and titanium and the Naval Ordnance Lab.
2. Nitinol has a shape-memory effect, allowing it to reform its original shape when heated.
3. The shape-memory effect occurs because of the way the atoms move in response to stretching and bending of the metal.
4. Nitinol is made up of small grains that are microns to nanometers across, each consisting of atoms arranged in a regular repeating pattern.
5. When nitinol is cooled to room temperature, its crystal structure changes, but the overall shape remains the same.
6. The shape-memory effect is caused by the twinned structure of nitinol, which consists of rhombuses that are mirror images of each other.
7. Nitinol can be shaped into various forms at high temperatures, and when cooled, it retains that shape.
8. When nitinol is heated, the atoms move and change the ratio of the two types of rhombuses, causing the metal to return to its original shape.
9. Nitinol has super elastic properties, allowing it to return to its original shape even after extreme deformation.
10. The super elasticity of nitinol is closely related to its shape-memory effect.
11. Nitinol is used in various commercial applications, including stents, eyeglasses, and car parts.
12. Nitinol is used in a type of engine that runs on a temperature difference between water and air.
13. The engine uses a loop of nitinol wire that was originally straight at a very high temperature, and as it's heated, it tries to straighten, causing the engine to operate.
14. Nitinol is used in medical devices, such as stents, which are inserted into blood vessels to keep them open.
15. Nitinol is used in high-end products, such as premium eyeglasses, which can be bent and twisted yet return to their original shape.
16. Nitinol is used in designs where reducing weight is critical, such as in the 2014 Chevrolet Corvette, where a nitinol device replaced a heavy motorized actuator.