751 ISSN 2075-1133, Inorganic Materials: Applied Research, 2018, Vol. 9, No. 4, pp. 751–756. © Pleiades Publishing, Ltd., 2018. Original Russian Text © M.A. Kaplan, M.A. Sevost’yanov, E.O. Nasakina, A.S. Baikin, K.V. Sergienko, S.V. Konushkin, A.G. Kolmakov, 2018, published in Materialovedenie, 2018, No. 2, pp. 23–27. Influence of the Surface Modification on the Mechanical Properties of NiTi (55.8 wt % Ni) Alloy Wire for Medical Purposes M. A. Kaplan a, *, M. A. Sevost’yanov a , E. O. Nasakina a , A. S. Baikin a , K. V. Sergienko a , S. V. Konushkin a , and A. G. Kolmakov a a Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow, Russia *е-mail: mishakaplan@yandex.ru Received September 26, 2017 Abstract—The mechanical characteristics of a titanium nickelide alloy are studied depending on the surface machining. The additional processing improves the characteristics. Keywords: titanium nickelide, shape memory effect, superelasticity, nanostructure, nanomaterial DOI: 10.1134/S2075113318040159 INTRODUCTION Shape memory alloys have a unique property to return to their initial shape after preliminary deforma- tion when the temperature changes [1]. Alloys that have these properties are the best candidates for cre- ation of self-expanding stent medical implants that reduce the risk of traumas during implantation owing to the reduction in the catheter cross section. When cooled, stents undergo plastic deformation for mount- ing on a catheter and, in the body, they restore the desired shape [2–5]. At present, out of all shape mem- ory materials, titanium nickelide is the most wide- spread and promising, since this material has unique physical and mechanical properties that are similar to the behavior of the tissues in the living human body. An implant on its basis can function in the body with- out tissue damage and destruction [2, 6]. Titanium nickelide is a unique material that has a significant drawback, the presence of nickel, which is toxic to the human body, in the material volume and on the surface [1, 7–22]. The release of nickel ions should be decreased or completely blocked. The solu- tion of this problem can be different processing of tita- nium nickelide, including mechanical treatment, which can also affect other properties of the material. This study describes investigation of the mechani- cal properties of titanium nickelide and their changes that result from different functional treatments. MATERIALS AND METHODS The specimens under study were wire with diame- ter of 280 μm made of titanium nickelide (55.8 wt % Ni, 44.1 wt % Ti) that was polished using a special pol- ishing machine on the basis of an SNP-0.1-150V machine to remove an oxide layer and contaminants and to decrease roughness. The setup is given in Fig. 1. The detailed chemical composition of the wire is given in Table 1. For polishing we used felt disks that were wetted with a polycrystalline diamond suspension using a DiaMaxx lubricant (Akasel) at sizes of the diamond Fig. 1. Setup for wire polishing based on an SNP-0.1-150V machine.