Corrosion Performance of Multiple Memory Material Processed Nitinol

Nitinol, which is a group of nickel-titanium alloys composed of nearly equiatomic nickel and titanium, finds increasing applications in the medical industry because of its unique properties. It is however well known that the corrosion performance and biocompatibility of Nitinol depends largely on its surface condition. In this study the novel multiple memory material processing technology was used to locally modify the transformation temperature and pseudoelastic properties of a monolithic Nitinol material. Up until now the effects of multiple memory material processing on the corrosion performance have not yet been investigated in great detail. In this work the effects of processing on the corrosion performance are realized by conducting in vitro cyclic potentiodynamic polarization corrosion tests in compliance with the ASTM F2129-08 standard for both processed and unprocessed material.  The surface conditions of the samples are also characterized using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS).