| Engineering Characteristics of Drawn Filled Nitinol Tube: Jeremy Schaffer - Richard Gordon *Fort Wayne Metals Research Products Corporation, Department of Engineering, 9609 Indianapolis Road, Fort Wayne, IN 46899 **Medical Metals LLC, 54 Danbury Road, Ridgefield, CT 06877 ABSTRACT The elastic behavior of various thermally set Nitinol-DFT®-Platinum composite wires was investigated in both axial and flexural modes. Two varieties of composite materials were analyzed, each unique in the amount of cross-sectional area made up of Platinum (See Figure 1). The measured properties of these composites were found to be partially dependant on the mode of testing employed, the mechanical properties of the core, and the methods of processing. Theoretical relationships were used to predict the loading and unloading plateau strengths, the stress hysteresis, and the ultimate tensile strength of the composite materials. These derived values were then compared with data obtained from actual testing. Additional work was done to study the effect of the platinum core on the permanent set of the composite in both axial and bending load situations. The low core composite was found to exhibit strength and permanent set characteristics very similar to solid nitinol wire. Keywords Nitinol composite, Niti-DFT-Pt, Niti-DFT-Platinum, Niti-DFT®-Pt, DFT wire, composite wire, nitinol wire, superelastic composite, pseudoelastic composite, radiopaque composite, radiopaque wire, radiopaque guidewire, nitinol guidewire, nitinol stent, DFT wire stent, stent, radiopaque stent, radiopaque guidewire, guidewire. INTRODUCTION The binary nickel-titanium alloy system, otherwise known as Nitinol, plays an important role in today’s medical device technology [1]. Nitinol has found use in a wide range of applications; the material is used in guidewires, stents, temperature-sensitive actuators, cardiac massage devices, etc. The fundamental benefit of NiTi over most other metallic alloys is its ability to return elastically after significant strain deformation. The strain recovery characteristics of Nitinol depend upon many variables including: processing methods, nitinol material composition, test temperature, mode of deformation, and material configuration [2]. Primarily due to its low density, Nitinol wire is often difficult to locate under fluoroscopic examination [4]. In recent years, advances in materials processing technology have allowed the use of Nitinol in various composite forms [3]. Highly dense cores such as Platinum, Tantalum, and Gold are capable of providing enhanced visibility under x-ray fluoroscopy. The three materials tested here were a solid nitinol wire, nitinol 10% platinum composite, and a nitinol 30% platinum composite wire (See Figure 1).
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