How Does Memory Metal Work?
- Solid metalmetal image by Ruta Saulyte from Fotolia.com
Most materials on Earth can exist in three phases: a solid phase, liquid phase and gas phase. However, memory metal has two different solid phases. The austenite phase exists above the temperature of phase change and has a very rigid, cube-like atomic structure while the martensite phase exists below the temperature of phase change and is much more malleable. - Forming metal with heathot rod image by sumos from Fotolia.com
While in the martensite phase, memory metal can be manipulated into various shapes. With the application of a relatively low amount of heat such as that from hot tap water or a hair dryer, it will change back to its original austenite phase. To change the shape of the metal in the austenite phase, it must be formed to the intended shape and held there mechanically while it is heated to temperatures higher than 500 degrees Celsius, then cooled very slowly. - Medical suppliesmedicine image by Joyce Wilkes from Fotolia.com
The properties of memory metal are very applicable in medicine and dentistry. Memory metals are used in orthodontic braces because the heat of the body causes the memory metal wire to apply pressure to the teeth and push them into position. These properties also cause memory metal stents to expand to their original shape when placed inside an artery to hold the desired blood vessel open. - Memory metal is used in helicopters.Helicopter image by Bube from Fotolia.com
Memory metals are also useful in household products and heavy industry. Common appliance thermometers such as those in coffee pots cause the device to switch off when heated to a certain temperature. This property can also allow eyeglasses to better retain their shape or cause a memory metal clamp to tighten. More large-scale applications include using memory metals to regulate the balance on helicopter blades. - Most coins are metal alloys.centimes image by Pascal P??chard from Fotolia.com
Although the nickel-titanium alloy is the most common memory metal, other alloys do exist. Examples include iron-manganese-silicon, copper-aluminum-nickel, copper-zinc-aluminum and gold-cadmium alloys.
