Nickel titanium Alloy sheet plate strip

Nickel titanium, also known as nitinol, is a metal of alloy of nickel and titanium, where the two elements are present in roughly equal atomic percentages.

Nitinol alloys exhibit two closely related and unique properties: shape memory and super-elasticity (also called pseudo-elasticity). Shape memory refers to the ability of Nitinol to undergo deformation at one temperature, and then recover its original, undeformed shape upon heating above its "transformation temperature". Superelasticity occurs at a narrow temperature range just above its transformation temperature; in this case, no heating is necessary to cause the undeformed shape to recover, and the material exhibits enormous elasticity, some 10-30 times that of ordinary metal.

Nitinol's extraordinary ability to accommodate large strains, coupled with its physiological and chemical compatibility with the human body has made it one of the most commonly used materials in medical device engineering and design.

• Free Recovery: Nitinol is deformed at a low temperature, and heated to recover its original shape.
• Constrained Recovery: The same, except that recovery is rigidly prevented, and thus a stress is generated.
• Work Production: Here the alloy is allowed to recover, but to do so it must act against a force (thus doing work).
• Superelasticity: As discussed above, here the Nitinol acts as a super spring.