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Mechanical Characteristics of Non-nickel Shape Memory Alloy of Medical Appointment

New shape memory alloy (Ti-20Nb-10Ta-5Zr) for production of minimally invasive implantation medical devices (cava filter) was tested for static mechanical properties. The material for investigations was wires with different thickness before and after thermal treatment in various conditions and surface mechanical treatment. The structure was investigated on a scanning electron microscope and on a Auger spectrometer. High indicators of strength and ductility were noted. The mechanical treatment of the surface and annealing in vacuum best affect it. Introduction Alloys with shape memory effect and superelasticity are now the most interesting in endoscopic implantology—when creating products like "stent" and KAVA-filter. When such devices operating and installing in the body, less destruction of the implant itself and tissue damage are ensured [1-3]. These properties are best manifested in titanium nickelide, but the composition of this material includes toxic nickel that can influence surrounding tissues directly from the surface of the implant or be released into physiological environments as a result of corrosion, leading to both destruction of the product and to damage of the body [4-13]. At the same time, it is possible to develop nickel-free alloys with a shape memory effect and superelasticity. In this paper, the formation and investigation of a nickel-free TiNbTaZr shape memory alloy is considered. Materials and Methods Using a five-fold electric arc melting with a non-consumable electrode in an argon atmosphere ingots of an alloy of various compositions with a mass of 60 grams were produced. The starting materials were iodide titanium, tantalum and niobium of high purity. After smelting, the ingots were subjected to homogenization annealing in a vacuum. After the ingot rolled in streams, the workpiece was subjected to rotational forging, dragged to a diameter of 0.28-2.63 mm. Dies heated. As a lubricant used Aquadag. With the accumulation of deformation of 50-70%, the workpiece was subjected to post-deformation annealing. The structure was investigated on a scanning election microscope (SEM) VEGA II SBU with the module INCA Energy for energy-dispersive analysis (TESCAN, Czech Republic) and on a JAMP-9500F Auger spectrometer (JEOL Co., Japan) in combination with ion etching at argon bombardment under an angle of 30°. A Ti-20Nb-10Ta-5Zr alloy was chosen for the tests. Structural analyzes confirmed the specified content of elements and their uniform distribution over the sample volume. A 280-μm wire was used for mechanical testing (Table 1). To stabilize the structure and exploited properties, the finished wire was subjected to thermal treatment at temperatures of 600 and 800 о С in various conditions in vacuum and on air. The samples annealed in vacuum were cooled together with the furnace