Papers by Keyword: Titanium Alloy

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Authors: Vasile Danut Cojocaru, Ion Cinca, Nicolae Serban, Doina Margareta Gordin, Mariana Lucia Angelescu, Elisabeta Mirela Cojocaru, Doina Raducanu
Abstract: In the present days titanium and titanium alloys are extensively studied and used as biomaterials due to their biological, mechanical and physical properties. During last year’s special attention was paid to β-Titanium alloys due to their low elastic modulus. The present study investigates the twinning deformation features occurred during multi-pass cold-rolling processing of a biocompatible Ti-Nb-Zr-Fe alloy. Twinning deformation features were investigated using EBDS analysis by means of Inverse Pole Figures (IPF’s), Pole Figures (IP’s) and computed Schmid factor (SF’s) for the possible {332}<113> twinning variants.
Authors: Sergey Dubinskiy, Vladimir Brailovski, Sergey Prokoshkin, Karine Inaekyan
Abstract: The technique and preliminary results of in situ X-ray diffraction analysis of the martensitic transformation in the newly developed Ti-Nb-Zr SMA for biomedical application are presented. To perform the in situ analysis, an original tensile stage, powered by a Ti-Ni SMA actuator and fit within the “TTK450” thermal chamber of a “PANalytical X’Pert Pro” diffractometer is designed, manufactured and validated. The tensile stage working principle and analysis methodology are described in detail. Preliminary results obtained during in-situ X-ray analysis of the phase transformations in Ti-Nb-Zr SMA are also presented.
Authors: Andreea Carmen Bărbînţă, Kamel Earar, Carmen Iulia Crimu, Lucia Anişoara Drăgan, Corneliu Munteanu
Abstract: Titanium alloys are widely used in medical applications, due to their good mechanical properties, high corrosion resistance and biocompatibility. The aim of this paper was to investigate the cytotoxicity of novel titanium alloys: Ti21Nb6Zr15Ta, Ti25Nb10Zr8Ta, Ti17Nb5Zr5Al, Ti7Nb7Zr2Al with fibroblast-like cells derived from human osteosarcoma cell line (HOS). The results were compared with that of conventional biomedical alloys, like Ti6Al7Nb and Ti6Al4V. In vitro citotoxicity of titanium alloys was evaluated by fluorescence microscopy and MTT colorimetric assay. The results showed that the materials analyzed had no cytotoxic effects on HOS fibroblast-like cells, permitting their attachment and proliferation. Also the new titanium alloys present a higher cell viability than that of the conventional alloys. As a consequence, the TiNbZrTa and TiNbZrAl alloys can be considered as potential candidates for biomedical applications.
Authors: Sergey Prokoshkin, Vladimir Brailovski, Karine Inaekyan, Andrey Korotitskiy, Sergey Dubinskiy, Mikhail R. Filonov, Mikhail Petrzhik
Abstract: The processes of structure formation in Ti-Ni and in Ti-Nb-Zr, Ti-Nb-Ta shape memory alloys (SMA) under thermomechanical treatment (TMT) were studied. The TMT comprised cold rolling with true strains from e=0.25 to 2 and post-deformation annealing. Differences in these processes between two groups of alloys are considered. The main conclusions are as follows: nanostructures created by TMT are useful for radical improvement of the SMA functional properties, and an optimum nanostructure (nanocrystalline structure, nanosubgrained structure or theirmixture) should be selected by taking into account other structural and technological factors.
Authors: Yuan Fa Ding, Wen Guo Huo, Xiang Dong Su, Lan Zhang
Abstract: A new self-lubrication concept based on the techniques including of dry grinding and solid lubricating was proposed for green grinding process. And a kind of self-lubrication grinding wheel was designed with solid powder lubricant and centrifugal impeller inside. The self-lubricating was achieved by the blow out of the solid powder lubricant from the inner cavity of the wheel by the centrifugal force to the grinding surface. The experiments were conducted to study the friction and wear properties of the new cylindrical wheel samples manufactured by the proposed concept. The results showed that the flow channel diameters of 1 to 1.5 mm are the best for the blowing out of the solid lubricant to realize the continuous lubricating. After grinding, the surface coating is even, and the sizes of the abrasive particles are relatively uniform with no peeling into blocks. Although there is a certain wear loss of the grinding surface, the wear rate of the particles on the sample wheels is less than that of the traditional grinding wheel. The computational simulation of the self-lubrication wheel is conducted with the RSM method with FLUENT software to analyze the flow field in the wheel cavity of solid lubricant inside, which is meaningful for the study of the motion of the solid lubricant and useful for optimum design of the wheel design to realize the best self-lubricating performance.
Authors: Miao Quan Li, Jiao Luo
Abstract: Isothermal compression of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy is conducted on a Thermecmaster-Z simulator at the deformation temperatures ranging from 1173 K to 1333 K, the strain rates ranging from 0.001 s-1 to 10.0 s-1 at an interval of an order magnitude and the height reductions ranging from 50% to 70%. The primary grain size is measured at an OLYMPUS PMG3 microscope with the quantitative metallography SISC IAS V8.0 image analysis software. A multi-scale constitutive model coupling the grain size, volume fraction and dislocation density is established to represent the deformation behavior of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy in high temperature deformation, in which the flow stress is decomposed a thermal stress and an athermal stress. A Kock-Mecking model is adopted to describe the thermally activated stress, and an athermal stress model accounts for the working hardening and Hall-Petch effect. A genetic algorithm (GA)-based objective optimization technique is used for determining material constants in this study. The mean relative difference between the predicted and experimental flow stress is 5.98%, thus it can be concluded that the multi-scale constitutive model with high prediction precision can efficiently predict the deformation behavior of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy in high temperature deformation.
Authors: Cui'e Wen, Yun Cang Li
Abstract: Titanium and some of its alloys have received considerable attention for biomedical applications in recent years due to their excellent biocompatibility, high corrosion resistance and relatively low elastic modulus when compared to other metallic implant materials such as Co-Cr alloys and stainless steels. However, these alloys can still suffer from inadequate biocompatibility; lack of biological fixation and biomechanical mismatch with the properties of bone in vivo. In this study, a new biocompatible Ti alloy, Ti4Ta4Sn, consisting of alpha and beta phases was fabricated and their mechanical properties were investigated. Moreover, the Ti alloy was scaffolded into a porous structure using powder metallurgy with an architecture and elastic modulus mimicking those of cancellous bone. Cell culture results indicated that the new porous Ti alloy scaffold possesses excellent in vitro biocompatibility.
Authors: Wen Wen Peng, Wei Dong Zeng, Qing Jiang Wang, Yan Chun Zhu
Abstract: A novel high-speed photography is introduced to determine the critical fracture strain of a near alpha titanium ally during hot compression deformation. This method precisely captures the nucleation site and propagation process of cracking, and thus is an excellent method to represent dynamically the hot-deformation fracture. Compared with the traditional way, it can significantly decrease the number of trials and improve the accuracy. Based on this method, the critical fracture strain is measured, and a critical fracture model is developed.
Authors: Jun Jie Xiao, Dong Sheng Li, Xiao Qiang Li, Ming Jin Xu
Abstract: In order to reduce the energy consumption and working procedure for manufacturing thin-walled titanium alloy components, a hot stretch-creep forming (SCF) technique via resistance heating is proposed to form the hard-to-form material. Firstly, the principle of hot SCF was introduced that the technique can manufacture titanium alloy components precisely because the residual stress relaxes in the material during the dwelling time. Secondly, the hot SCF equipment via resistance heating was developed, which makes use of electrical current for heating the titanium materials to improve their ductility. Then based on a set of optimized process parameters, including forming temperature, stretch velocity, post stretch percentage and dwelling time, a comparative experment of single curvature Ti-6Al-4V alloy sheet components was conducted via this innovative technology to examine the hot SCF equipments and the effect of creep forming. Results show that the component precision of the hot SCF is more precise than that of the hot stretch forming (SF) due to the creep in the stress relaxation period. Comparing to the as-received material, the yield strength of the material suffered hot SF decreases a little; while the strength suffered hot SCF increases a little. This novel technique shows a promising future to manufacture titanium sheet or profile components precisely as a feasible and cost-effective way.
Authors: Nam Su Kwak, Jae Yeol Kim, Dae Gwang Park
Abstract: In this study, piezoelectric actuator, flexure guide, power transmission element and control method are considered for nanopositioning system apparatus. The main objectives of this thesis were to develop 2-axis nanostage which enables 2-axis control with the aid of piezoelectric actuator, and to improve the precision of the ultra-precision lathe (UP2) which is responsible for the ductile mode machining of the hardened-brittle material where the machining uses a the single-crystal diamond. Through simulation and experiments on ultra-precision positioning, stability and priority of the nanopositioning system with 2-axis nanostage and control algorithm are developed using Matlab/Simulink. Then the system, is applied to analyze surface morphology of the titanium alloy (Ti-6Al-4V)
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