Nickel-titanium (NiTi) is a remarkable metal alloy that is representative of “smart materials” that respond to a stimulus in a predictable manner. The wire sample of NiTi used in this unit can be bent at room temperature, but will return to its linear shape when heated by hot air or water as its atoms move in a kind of “atomic ballet.” Moreover, the wire can be heated to the much higher temperature of a candle flame (~500 degrees C), where it can be trained to “remember” a new shape. Subsequently, when the wire is distorted at room temperature and heated by hot air or water, it will return to this new shape. Rods of NiTi can be used to show that the flexibility, hardness, and even its acoustic characteristics are all affected by its temperature.
This unit could stand alone with a scope that is limited to understanding memory metals. It could also be used as a supplement to an existing chemistry curriculum and provide for a unique way to introduce or reinforce other basic chemistry topics.