Shape Memory Alloy returns to its pre-deformed shape when heated

Certain materials feature a shape memory effect — after deformation, they return to their original shape when heated. They’re shape memory alloys. A regular paperclip isn’t a shape memory alloy, it’s made out of steel. So don’t be disappointed when it doesn’t form its shape back when heated up. 

A shape-memory alloy (SMA) is an alloy that can be deformed when cold but returns to its pre-deformed (“remembered”) shape when heated. It may also be called memory metal, memory alloy, smart metal, smart alloy, or muscle wire. Parts made of shape-memory alloys can be lightweight, solid-state alternatives to conventional actuators such as hydraulic, pneumatic, and motor-based systems. They can also be used to make hermetic joints in metal tubing.

the material shown in the video is Nitinol, an alloy of nickel and titanium which is really interesting because it exhibits both shape memory and super elasticity properties. It’s an expensive material to buy and also difficult/expensive to manufacture, so it’s considered specialized and really only widely used in industries like medical devices or aerospace.

The shape can be modified to virtually anything, so long as you can make the material into that shape in the first place. You heat treat the Nitinol at high temperatures (typically 500C+) in your desired shape to “lock it in”.

Additionally, the temperature at which Nitinol has shape memory (springs back to its original shape) is adjustable for your application.