Shape memory alloys: how metal remembers its original form

*A Taste of Physics for the Weekend*

Alloys of certain metals (such as nickel-titanium) exhibit a "shape memory effect."
This effect allows these materials to "remember" their original shape and return to it when heated.

How does it work?

Shape memory materials exist in two phases:
**Austenite** – the phase of the material above a certain temperature. In this phase, the material's original shape is set.
**Martensite** – the transition to this phase occurs by rapidly cooling the material.

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When the pin and spring shown in the video were manufactured, they were heated to a high temperature and given their base shape.
They were then rapidly cooled, transforming them into the pin and spring we recognize — easily bent and reshaped.

Heating the material transitions it into the austenite phase, restoring it to its original shape.

#taste_of_physics

Shape memory alloys: how metal remembers its original form