Nickel Titanium (also known as Nitinol or NiTi) is in the unique class of shape memory alloys. A thermoelastic martensitic phase transformation in the material is responsible for its extraordinary properties. Nitinol properties include the shape memory effect, superelasticity, and high damping capability. These technical properties of NiTi shape memory alloys can be modified to a great extent by changes in composition, mechanical working, and heat treatment.
Johnson Matthey has accumulated over 20 years of specialized Nitinol research that gives us the expertise to exploit Nitinol shape memory and superelastic properties and design products for your medical devices which can meet the most exacting specifications . We specialize in high volume applications where we can implement automated processes to produce your component at minimal costs. And, we develop the custom fixtures to provide efficient shape setting of the final design. We offer Nitinol wire, ribbon and tubing in a variety of sizes, and our Nitinol sheet is the thinnest in the industry. We also provide precision Nitinol micromachining to create a limitless array of shapes and sizes.
Nitinol Shape Memory Alloys undergo a phase transformation in their crystal structure when cooled from the stronger, high temperature from (Austenite) to the weaker, low temperature from (Martensite). this inherent phase transformation is the basis for the unique properties of these alloys - in particular, Shape Memory and Superelasticity.
When shape memory alloys are in their martensitic form, they are easily deformed to a new shape. However, when the alloy is heated through its transformation temperatures, it reverts to austenite and recovers its previous shape with great force. This process is knows as Shape Memory.
The temperature at which the alloy remembers its high temperature from when heated can be adjusted by slight changes in alloy composition and through heat treatment. In the Nickel Titanium alloys, for instance, it can be changed from above +100 deg. C to below -100 deg. C. The shape recovery process occurs over a range of just a few degrees and the start or finish of the transformation can be controlled to within a degree or two if necessary.
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These unique shape memory alloys also show a Superelastic behavior if deformed at a temperature which is slightly above their transformation temperatures. This effect is caused by the stress-induced formation of some martensite above its normal temperature. Because it has been formed above its normal temperature, the martensite reverts immediately to undeformed austenite as soon as the stress is removed. This process provides a very springy, "rubberlike" elasticity in these alloys.
O.D.: 0.008" (0.203mm) to 0.400" (10.16mm)
Wall thickness to 0.002" (0.05mm)
natural oxide, etched OD/ID, centerless ground, mechanically-cleaned ID
Diameters from 0.012" (0.3048mm) to 0.250" (6.35mm)
black oxide, amber/brown oxide, natural oxide, polished, etched, centerless ground
Thickness from 0.002" (0.051mm) to 0.080" (2.03mm)
natural oxide, etched
Thickness from 0.0007"(0.0127mm) to 0.002"(.051mm) Width to 3.00" (76.2mm)
|natural oxide, etched|