If you have ever wondered why nitinol is so expensive, it has to do with its pseudo-elasticity and the unique processing requirements for making this alloy. It’s very difficult to machine, and its innate resistance to deformation also resists processes like abrasive cutting. In addition, it’s extremely sensitive to temperature changes that occur when the material is heated or cooled. As a result, it’s more expensive than some of the conventional metals used in manufacturing.
Nitinol is a unique material with thermal shape memory and superelastic properties that have become popular in medical devices. These features allow designers to create devices that are far more flexible than traditional materials and systems. In medical applications, nitinol can be made into reinforcement braiding and coiling for catheter tubing and shafts, coiled or formed stents, stone retrieval baskets, medical guide wires, and dental archwires.
Its shape memory makes nitinol a good choice for in-body device use because it can be bent and twisted through the body, but once it is back to its original form, it “remembers” that form. This can make a medical procedure much easier and more accurate than it would be using a more conventional metal.
This shape memory effect can be adjusted by slight changes in the alloy composition and through heat treatment, as well. The transition temperatures can be selected to match the device’s application; for instance, nitinol’s transition temperature to its high-temperature form is close to human body temperature.