Effect of prestrain on martensitic transformation in a Ti 46.4 Ni 47.6 Nb 6.0 superelastic alloy and its application to medical stents

The effect of applied strain on martensitic transformation in a superelastic Ti 46.4 Ni 47.6 Nb 6.0 alloy at room temperature was investigated by tensile tests, differential scanning calorimetry measurements, and X‐ray diffraction. Reverse transformation starting ( A s ) and finishing ( A f ) temperatures increased with the application of tensile‐strain over 13%, the undeformed specimen showing A s = −29.2°C and A f = 17.9°C, while the 13% predeformed alloy exhibited A s = 37.1°C and A f = 40.2°C. Furthermore, the values of the A s and A f for the predeformed alloy almost recovered to those of the undeformed alloy when heated to about 42°C and then showed superelasticity again at room temperature. This characteristic is significant for application in sensors, actuators, and medical devices. Especially, medical stents with such qualities show promise as a new class of self‐expandable stents with both excellent mountability and deliverability. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006