Nitinol Description
Nitinol is a metal alloy, sometimes also called Shape Memory Alloy (SMA). Nitinol alloys exhibit two closely related and unique properties: shape memory and superelasticity. Shape memory refers to the ability of a material to undergo deformation at one temperature, and then recover its original shape upon heating above its "transformation temperature". Superelasticity occurs in a narrow temperature range just above the transformation temperature; in these conditions, no heating is necessary to return to the pre-deformation shape.
Shape Memory Alloys (SMAs) have been considered one of the most promising smart materials. They can provide novel solutions in several fields, for various applications (e.g. actuators, biomedical applications, clamping systems, etc.). Among the commercially available Shape Memory Alloys, nickel–titanium (Ni–Ti and Ni–Ti-based) ones are outstanding due to their excellent performance and reliability. In addition to its strain recovery, Ni–Ti is attractive for medical applications due to its biocompatibility, corrosion resistance, and fatigue behavior.
Glossary
Shape Memory Effect
"Shape Memory" describes the restoration of the original shape of a plastically deformed sample upon heating.
Superelastic Effect
An elastic (reversible) response to an applied temperature, caused by a phase transformation between the austenitic and martensitic phases of a crystal.
Ms- Initial temperature for austenite to martensite transition
Mf- Final temperature for austenite to martensite transition
As- Initial temperature for martensite to austenite transition
Af- Final temperature for martensite to austenite transition
