Which material can bend into different shapes and remember its original shape when heated?

• A. Polymorph
• B. Thermochromic ink
• C. Shape memory alloy
• D. Composite materials

Answer: (C)

Shape memory effect is the idea that a material can be deformed into one shape and then return to its original form when heated. Shape memory alloys, like nickel-titanium (Nitinol), show this clearly. They can be bent or formed into a new shape at a lower temperature, and when you heat them above a specific transition temperature, their crystal structure changes and they snap back to the shape they “remember.” This memory of the original shape upon heating is what sets them apart.

Polymorph is a heat-softenable plastic you can reshape by heating, but it won’t automatically revert to its initial shape when heated; it stays in the new shape unless you reshape it again. Thermochromic ink changes color with temperature, not shape. Composite materials are engineered blends for specific properties and don’t inherently remember a prior shape when heated.