Shape Memory Alloys: Titanium-Nickel
A shape memory alloy is a type of metal that can be swayed from its original shape and return back to it once heat is applied to it. Shape memory alloys are also known as shape memory metals and have interesting physical properties that make them extremely useful in and out of industrial settings. Perhaps the most well-known shape memory alloy is the titanium-nickel (Ti-Ni) family which is composed of 50-50 atomic percent of titanium and nickel and can be used for a wide range of applications.
The physical properties of titanium-nickel alloys are largely due to the fact that they are composed of two different metals with vastly different atomic structures. As a result, the alloys can exist in two different ways: a highly flexible plastic form as well as a structural shape. When the alloy is in the plastic form, it can be manipulated into various shapes and sizes, whereas in the structural form it has memory of its original shape, thus allowing it to “memorize” and return back to its original state once it is hot enough. The alloy can also act as a spring, allowing it to contract or expand depending on the amount of heat it is exposed to. The alloys can go through 500 or more cycles of shape-memory behavior without losing their properties.
Because of their unique physical properties, titanium-nickel alloys are used in a variety of industrial and consumer applications. One of the more common uses for titanium-nickel is within mechanical movements, such as in motors, pumps, and other moving parts. Alloys can be used to open and close a door without any electrical power or leverage, as well as to create valves. It can also be used for medical applications such as for implanting stents within the body, as well as for creating artificial muscles.The alloys have also been used in a variety of consumer applications, such as in eyeglass frames and watch hands.
The alloys are popular not only because of their shape memory behavior, but also because they can be easily manipulated, are corrosion resistant, and possess good fatigue strength. They can also be easily formed into various shapes and sizes, and are relatively cheap to produce.
Shape memory alloys have a wide range of applications, and the titanium-nickel alloys provide a great option for various industrial and consumer uses. The alloys are easy to work with, possess excellent physical properties, and are relatively cheap to produce. They are an ideal option for when a shape needs to be remembered over a long period of time, and provide an excellent solution for numerous applications.
