Nitinol is an alloy of nickel and titanium with two unique properties: Super Elastic and Shape Memory. Each property is achieved through a specific alloy ratio between nickel and titanium — both properties cannot be achieved simultaneously.
With the appropriate heat treatment, nitinol can be "trained" to a specific shape. If the material's shape is changed and then heated, it returns to its original trained shape. Nitinol changes its phase from austenite to martensite upon deformation, and returns to the austenitic phase when heated at 650 MPA pressure.
The difference between the two types is the activation temperature: if at a low temperature the type is called Super Elastic, and at a high temperature it is Shape Memory.
Nitinol is FDA-approved for use inside the human body and is not considered a foreign body. Its primary use is in medicine: exploiting its force capability and reducing fatigue failure.
SM500 50% nickel alloy, Shape Memory with low activation temperature.
SM495 49.5% nickel alloy, Shape Memory with high activation temperature.
SE506 50.6% nickel alloy, Super Elastic with low stiffness and thermal stress.
SE508 The most common Nitinol alloy, containing 50.8% nickel, with the best stress and stiffness profile for implants.
SE510 The stiffest and strongest alloy in the Super Elastic type, containing 51% nickel.
SE508 ELI Identical mechanical properties to SE508 but with lower oxygen content in manufacturing, providing better fatigue failure resistance.
