Nitinol Alloys

Nitinol, a nickel-titanium shape-memory alloy

Nitinol is a near-equiatomic alloy of nickel and titanium, and it is bought for a mechanical effect rather than for heat or oxidation resistance. A reversible transformation between its martensitic and austenitic phases — which sits near room temperature and is tuned by composition and processing — gives the alloy two behaviours: shape memory, where a deformed part returns to a preset shape when warmed through the transformation, and superelasticity, where strains far beyond what an ordinary metal can recover spring back on unloading at constant temperature. It contains no chromium and is not a high-temperature alloy.

Key Properties:

• Shape memory — recovers a preset shape on heating through the transformation
• Superelasticity — recoverable strain well beyond that of conventional alloys
• Fatigue and kink resistance in the superelastic condition
• Corrosion resistance from a titanium-oxide surface film
• Biocompatibility, which is why it dominates minimally invasive medical devices

Applications:

• Medical devices — self-expanding stents, guidewires and catheter components
• Orthodontic archwires
• Actuators and thermal switches
• Eyewear frames and flexible antenna wire

Available Forms:

• Nitinol Sheets
• Nitinol Plates
• Nitinol Strips
• Nitinol Rods and Round Bars
• Nitinol Wires

Specifications by Product Form

Nitinol (N01555) is supplied to a different standard in each form. Quote the one that matches the product you are ordering.

These are the forms the producers publish: ATI lists sheet from 0.020 in, plate to 0.250 in, rod from 0.1 to 2 in and wire from 0.010 to 0.099 in, and Fort Wayne Metals draws the strip and fine wire. Sizes outside those ranges and other shapes are quoted against the mill programme in force at the time of enquiry. Ask us for the size and the austenite finish temperature you need — A_f is agreed per order rather than fixed by the grade.