Shape memory materials display an unusual property of "remembering" the shape they were formed into at high temperature. They experience a solid state phase change, in which atoms are rearranged, but the material remains a solid. If a piece of shape memory metal alloy wire is deformed, for example, it will return to its original state when exposed to the heat of a hair dryer—the heat triggers the "memory" of where the atoms were at the time of its production under similar heat.
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