Papers by Keyword: TiNi Alloy

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Authors: Jin Kyung Lee, Young Chul Park, Sang Ll Lee, Joon Hyun Lee, Jong Baek Lee
Abstract: Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite (MMC). TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress using shape memory effect in the matrix. A hot press method was used to create the optimal condition for the fabrication of shape memory alloy (SMA) composite. The bonding effect between the matrix and the reinforcement within the SMA composite was strengthened by the cold rolling. The fabricated composite by these processes can be applied as a part of the aircraft, and this part is operated under severe flying condition such as low temperature and high pressure. In this study, an acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/Al6061 SMA composite at low temperature condition. The results showed that the tensile strength of the TiNi/Al6061 SMA composite increased with the TiNi reinforcement at low temperature condition, but the strength for the specimen subjected to the cold rolling decreased. AE parameters of AE counts, amplitude and energy were useful to evaluate the microscopic damage behavior of the composite.
Authors: Jin Kyung Lee, Young Chul Park, Sang Ll Lee
Abstract: A smart material is used as spectacle frames and brassiere frames, and partly in medical supplies because of its shape memory effect. The smart composite can be used on the wing of an airplane instead of the existing aluminium to control crack propagation. In this study, the smart composite was fabricated by a hot press method. TiNi alloy as reinforcement and Al6061 as matrix were used, respectively. The mechanical properties of the smart composite under thermal shock cycles were evaluated. In addition, Acoustic Emission techniques were also used to clarify the damage behavior of the smart composite under thermal shock cycles nondestructively.
Authors: Hong Gun Kim, H.K. Noh, Young Tae Cho, J.Y. Kim, S.K. Park, Dong Joo Lee
Authors: Wei Cai, Y. Cheng, Y.F. Zheng, Hong Tao Li, Lian Cheng Zhao
Abstract: Ti-50.6 at.% Ni shape memory alloy was coated with tantalum using multi arc ion-plating technique with the aim to increase its radiopacity and biocompatibility. The surface characteristics were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results of XPS survey spectra show that a thin oxide film are formed inside tantalum coating as a result of natural passivation of Ta in atmosphere. The hemocompatibility was evaluated in vitro by clotting time and platelet adhesion measurement. The results of our study showed that the clotting time of tantalum was higher than that of the TiNi alloys and no sign of accumulation and only slight pseudopodium was observed on the tantalum coatings, suggesting that the tantalum coatings can improve the biocompatibility of TiNi alloy.
Authors: G. Oomi, S. Aduma, I. Kosaka, T. Kagayama, Minoru Nishida
Authors: Vyacheslav M. Gundyrev, Vitaly I. Zel'dovich
Abstract: We measured integrated intensities of 26 reflections of the B2-phase of titanium nickelide single crystal and determined structure factors for these reflections. Based on the structure factors, mean squares of displacements of Ni and Ti atoms with respect to the crystal-lattice sites have been determined. After that we determined the mean squares of atomic displacements Ni and Ti in temperature range of existence of the B2-pase, at temperatures Т1=328 K and T2=376 K. We separated the mean squares of atomic displacements Ni and Ti into static and dynamic ones. The mean squares of dynamic displacements of Ni and Ti atoms are identical, but the mean square of static displacements is greater by a factor of 4.7 for Ni atoms than for Ti atoms. The Debye temperature calculated from the mean squares of displacements of Ni atoms is 360 K; that calculated for Ti atoms in a similar way is 390 K. The large value of complete atomic displacements in TiNi is due to static rather than dynamic displacements of atoms, mainly due to static displacements of nickel atoms.
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