Memory Metal

A pair of glasses bend in heat because they are made of memory metal.
Memory metal eyeglass frames can be bent in the presence of hot steam from boiling water.

"Memory Metal" refers to a specific type of metal alloys that remember their shape. This "smart" property is the result of the substance's ability to undergo a phase change - a kind of atomic ballet in which atoms in the solid subtly shift their positions in response to a stimulus like a change in temperature or application of mechanical stress. Many diverse applications have been developed for "memory metal" and other "smart" materials. These uses include eyeglass frames, cardiac stints, coffee pot thermostats, electrical connectors, deicing systems, heat pipes, clamps, and sculptures.