Nitinol With Improved Ductility

Commercial forms of superelastic Nitinol often exhibit limited ductility (i.e. ≤20%). As devices become more miniaturized and being applied in more tortuous anatomies it is desirable to employ a Nitinol with extraordinary ductility.  Thereby a process is presented to improve the ductility of Nitinol where up to 50% elongation to failure can be achieved while maintaining key properties such as stiffness and UTS. It appears that the transition of the elongation to failure from less than 15% to greater than 30% presents as nearly a step function with heat treatment and time. The mechanisms governing such step function behavior will be discussed. Furthermore, the impact of this increased ductility on durability in different loading modes such as rotary bending and tension-tension at various mean strains will also be presented.