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Physical Properties
Nitinol (Nickel-Titanium-Naval-Ordnance-Laboratory) was
invented in 1962 by the U.S. Naval Ordnance Laboratory.
They were seeking a nonmagnetic, high hardness, noncorrosive
material for hand weapons and tools. After melting 55%
nickel and 45% titanium, an alloy was created with extraordinary
shape memory characteristics. Later on it was determined
that the shape memory characteristics of the Nickel Titanium
would be the "Ultimate" orthodontic wire material.
After analysis of physical properties much more refined
(cleaner) material was developed for orthodontic use.
Nitinol exhibits unique property of thermoelastic martensitic
transformation, which is not seen in any other engineering
material. This transformation is responsible for shape
memory and superelasticity being exhibited by the alloy.
Following deformation below the transformation range,
the ability called shape memory allows recovery of a predetermined
shape upon heating above the transformation range. Super-elasticity
is the ability to recover a shape upon removal of an applied
stress over a narrow range of deformation temperatures.
The strain recovered with shape memory or superelasticity
provides nearly ten times the elastic spring back of other
alloys such as stainless steel.
1 Glossary of Terms.
2 Misconceptions
3 Clinical Tips
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NiTi (Nitinol) Information
