======Nitinol Shape Memory Alloy======


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**Alternative titles:** Smart Wire Demonstration
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====Summary====                   
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====Procedure====  
  - Provide volunteers with two types of wires: straight ordinary wire and straight Nitinol wire.  
  - Ask volunteers to bend the wires into any shapes such as coils, springs, or zigzags.  
  - Select a volunteer with ordinary wire. Hold the wire with pliers and heat it using a heat gun; the wire will simply get hot without changing shape.  
  - Retrieve a bent Nitinol wire from a volunteer. Hold it with pliers and heat it using the heat gun; the wire will straighten and return to its original shape.  
  - Allow the wire to cool, then have a volunteer bend it again. Reheat to show that the shape-memory effect is repeatable.  
  - Explain that the effect occurs because Nitinol atoms shift back to their “remembered” structure at a certain transition temperature.



====Links==== 
Nitinol Amazing Shape Memory Alloy - Action Lab Shorts: 
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📄 Shape-Memory Alloys - David Pogue: [[https://www.pbs.org/wgbh/nova/assets/education/making-stuff/stuff-toolkit-smarter-demo.pdf]]\\


====Variations====
  * Compare Nitinol to other smart materials, such as shape-memory polymers, to highlight differences.  
  * Use different thicknesses of Nitinol wire to observe how the heating time changes.  
  * Perform the demonstration with multiple Nitinol wires bent into different shapes for a dramatic visual effect.



====Safety Precautions====
  * Use heat-resistant gloves when handling wires and the heat gun.  
  * Do not point the heat gun toward the audience.  
  * Ensure wires are completely cooled before allowing audience members to handle them.  
  * Place the heat gun out of reach after use to cool safely.




====Questions to Consider====
  * Why does Nitinol return to its original shape when heated? (Its crystal structure undergoes a phase change at the transition temperature, restoring its “remembered” shape.)  
  * How is Nitinol different from ordinary metals? (Ordinary metals expand with heat but do not retain memory of a previous shape.)  
  * Where are shape-memory alloys like Nitinol used in real life? (Examples include orthodontic braces, thermostats, medical stents, and automatic valves.)