I work with Shape Memory Alloys. They are a special metal with two phases. If you heat treat them, you can train them to be one shape. For example, lets say you train a wire to be curly, like a spring. If you take that wire and straighten it out, and then apply heat, it will curl back up into its original shape. I just got my SMA strips for the deployment system I am working on at SEI for the SMARTSat. Here is a short video of the little strip. Its trained shape is straight, so to deform it I bent it. Enjoy!