Shape Memory Alloys (SMA)
Definition:
Shape Memory Alloys (SMAs) are smart materials that can remember their original shape. When deformed at lower temperatures, they can return to their original shape upon heating, producing an actuating force.
Key Characteristics:
- Ability to undergo large deformations and recover their original shape when heated
- Thermo-responsive: Change shape based on temperature
- Exhibit pseudo-elasticity or superelasticity
- Good corrosion resistance (especially in biomedical SMAs like nitinol)
Common SMA Example:
- Nitinol (Nickel-Titanium alloy):
- High corrosion resistance (like stainless steel)
- Biocompatible, ideal for medical applications
Applications:
- Biomedical field:
- Stents for veins and arteries
- Biodegradable surgical sutures that self-tighten
- Consumer products:
- Superelastic spectacle frames
- Coffee-pot thermostats
- Automotive industry:
- Self-repairing car bodies that recover shape when heated
Note on Shape Memory Polymers:
- Polymers with similar behavior to SMAs
- Regain their original shape when heated
- Used in:
- Self-healing car components
- Smart textiles
- Biodegradable medical devices