Alloys are metals consisting of two or more elements, and are commonly formed to improve properties in comparison to pure metals. Shape memory alloys remember their original structure or polymorph, and reverting back to the original structure can be initiated by a variety of factors.
For this example, thermal effects are taken into consideration, where heat is applied, triggering the alloy to return to its original structure after being deformed.
This experiment will demonstrate how heat affects alloys!
The piece of Nitinol wire in this kit was heat treated or set to be straight in its original (austenite) phase. During this demo, the atoms in the wire will undergo a phase transformation between the low temperature martensite and the high temperature austenite.
Take the wire and wrap it around your finger to form a spring shape*. It will remain in that shape until it is heated to its transformation temperature. Obtain a cup of hot, nearly boiling water (please be careful!). Hold on to one end of the wire and dip the other end into the hot water (you can use pliers if you want). What happened?