Gunther Sergey; Chekalkin Timofey; Hodorenko Valentina; Kang Ji-hoon; Kim Ji-soon; Gunther Victor
Abstract
Despite the well-known advantages of TiNi-based alloys, the cost of production is still high. The alloys are traditionally made by vacuum induction melting technology followed by vacuum arc remelting to get ingots which are further worked mechanically to final or semi-finished items. The special attention ...
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Despite the well-known advantages of TiNi-based alloys, the cost of production is still high. The alloys are traditionally made by vacuum induction melting technology followed by vacuum arc remelting to get ingots which are further worked mechanically to final or semi-finished items. The special attention is paid by a thin wire which can be used as a suture material or for a tissue grafting. Thin TiNi yarns are produced by cold drawing via dies with the intermediate annealing. When a diameter is about or over 1 mm, the existing solutions give clear insight into a general idea about how to change the structure and properties of the alloy. However, when the size is definitely scaled-down to 90 μm and less, serious difficulties appear because such yarn requires thoroughly care in mechanical processing steps and repeated heat treatment increases the expense making the product costly and unprofitable. As working steps and heat treatment of the ultrathin TiNi-based wire (UW) are to be more predictable and controllable, there was suggested an infrared (IR) drawing heater due to the radial warming system located prior to the die. In hope to provide a more comprehensive understanding of this issue, a study on how the IR heating method influences on surface properties of the UW, comparing the various effects of heat treatment was carried out using the designed IR heater. The study covers the effect of oxide layer composition and its modification on the properties of the wire IR-heat drawn. Strong correlations were observed between oxide layer thickness and strength characteristic of the resultant wire. These findings elucidate the role of the oxide layer and its composition on a quality of the UW drawing process.
Yasenchuk Yu. F.; Artyukhova N. V.; Chekalkin T. L; Anikeev S. G.; Kim Ji-Soon; Kang Ji-Hoon; Gunther V. E
Abstract
Modern medical technologies have developed many new devices that can be implanted into humans to repair, assist or take the place of diseased or defective bones, arteries and even organs. The materials, especially porous ones, used for these devices have evolved steadily over the past twenty years with ...
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Modern medical technologies have developed many new devices that can be implanted into humans to repair, assist or take the place of diseased or defective bones, arteries and even organs. The materials, especially porous ones, used for these devices have evolved steadily over the past twenty years with TiNi-based alloys replacing stainless steels and titanium. The aim of the paper is to presents results for examination of porous TiNiMoCo-based alloy intended further to be used in clinical practice. Porous TiNi-based alloys showing shape memory effect were obtained by the methods of reaction and diffusion sintering with cobalt additives. From the results of the analysis of temperature dependences determined by the measurement of electrical resistivity and shape memory effect test, the effect of cobalt addition on the martensitic transformations in sintered body is described. The addition of cobalt during reaction and, especially, diffusion sintering, results in a decrease in the internal stresses in the TiNi phase. The addition of Co more than 1 at. % led to precipitation hardening of the alloy. Cobalt at concentrations studied in the work led to suppression of martensitic phase transformation.