| Yes used in practice! I do production support in this field. Nitinol is used in lots of vascular devices. At least in my company, they used it first in guidewires just for the super elasticity, as a torturous vessel may kink a steel wire. At first there were bare metal stents, steel and later CoCr alloy. But last 15 years or so we've gotten self expanding stents that use the shape memory effect to set the final diameter at body temperature during processing, then the Stent is collapsed down into a catheter delivery system. There are various designs for releasing the collapsed Stent into the vessel, but once there it springs open thanks to super elasticity and apposes (conforms) up to the vessel wall, where good apposition gives lower chance of thrombosis formation. There are lots of other devices too... embolic protection devices (niti frame with a net over it, to catch shmoo from flowing to brain during a carotid procedure )
And various heart repair devices. It's great for intervention devices because you can collapse a device down small enough to be advanced by radial or femoral artery access and let's you do things that would normally require cracking someone's chest open for heart surgery. But the material is finicky, and it could take a decade for a smelter to get their niti process worked out. A very small difference in alloy composition disproportionately affects the crystal structure transition temperature, which impacts whether device will behave in service conditions |