Laminated NbTi-on-Kapton Microstrip Cables for Flexible Sub-Kelvin RF Electronics

Science.gov (United States)

Walter, Alex B.; Bockstiegel, Clinton; Mazin, Benjamin A.; Daal, Miguel

2017-11-01

Large arrays of superconducting devices such as microwave kinetic inductance detectors require high density interconnects from higher temperatures with minimal heat load, low loss, and negligible crosstalk capable of carrying large and overlapping bandwidth signals. We report the fabrication of superconducting 53 wt% Nb-47 wt% Ti (Nb-47Ti) microstrip transmission lines laminated onto flexible polyimide substrates with lengths up to 40 cm and up to ten traces. The 50 Ω traces terminate in G3PO coaxial push-on connectors. We found transmission losses of 2.5 dB and a nearest-neighbor forward crosstalk of -25 dB at 8 GHz on a typical 5 trace, 1.8-cm-wide, 0.198-mm-thick, 22-cm-long flex cable at 30 mK. A simple two-port analytical model and subsequent Sonnet simulations indicate that this loss is mainly due to a complex impedance mismatch from wirebonds at the end connector without which the insertion loss would be data show that the 0.198-mm-thick flex cables tested have roughly equivalent thermal conductance per trace below 4 K compared to the 0.86 mm Nb-47Ti coaxial cables.

Analysis of the quench propagation along Nb3Sn Rutherford cables with the THELMA code. Part I: Geometric and thermal models

Science.gov (United States)

Manfreda, G.; Bellina, F.

2016-12-01

The paper describes the new lumped thermal model recently implemented in THELMA code for the coupled electromagnetic-thermal analysis of superconducting cables. A new geometrical model is also presented, which describes the Rutherford cables used for the accelerator magnets. A first validation of these models has been given by the analysis of the quench longitudinal propagation velocity in the Nb3Sn prototype coil SMC3, built and tested in the frame of the EUCARD project for the development of high field magnets for LHC machine. This paper shows in detail the models, while their application to the quench propagation analysis is presented in a companion paper.

The first cable for the HL-LHC produced at CERN

CERN Multimedia

Brice, Maximilien

2016-01-01

A Rutherford cabling machine is operated in the superconducting laboratory in building 163. The machine was used for the production of the Nb-Ti cables in the LHC magnets. Today, it is operated for the assembly of the high-performance cables, made from state-of-the-art Nb3Sn conductor, for the LHC High Luminosity Upgrade. Key elements of the machine are of a precision Turkshead equipped with a variable power drive, a caterpillar, a dimensional control bench, a data acquisition system, and a take-up unit. The video shows the production of a long length Rutherford cable, made from 40 Nb3Sn strands, that will be use in a 11 T LHC High Luminosity dipole magnet. The wiring machine is the only one left in Europe able to do such a job.

The first cable for the HL-LHC produced at CERN

CERN Multimedia

Brice, Maximilien

2016-01-01

A Rutherford cabling machine is operated in the superconducting laboratory in building 163. The machine was used for the production of the Nb-Ti cables in the LHC magnets. Today, it is operated for the assembly of the high-performance cables, made from state-of-the-art Nb$_{3}$Sn conductor, for the LHC High Luminosity Upgrade. Key elements of the machine are of a precision Turkshead equipped with a variable power drive, a caterpillar, a dimensional control bench, a data acquisition system, and a take-up unit. The video shows the production of a long length Rutherford cable, made from 40 Nb$_{3}$Sn strands, that will be use in a 11 T LHC High Luminosity dipole magnet. The wiring machine is the only one left in Europe able to do such a job.

Comparison Between Nb3Al and Nb3Sn Strands and Cables for High Field Accelerator Magnets

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Kikuchi, A.; Barzi, E.; Chlachidze, G.; Rusy, A.; Takeuchi, T.; Tartaglia, M.; Turrioni, D.; Velev, V.; Wake, M.; Zlobin, A.V.; /Fermilab

2010-01-01

The Nb{sub 3}Al small racetrack magnet, SR07, has been successfully built and tested to its short sample limit beyond 10 Tesla without any training. Thus the practical application of Nb{sub 3}Al strands for high field accelerator magnets is established. The characteristics of the representative F4 strand and cable, are compared with the typical Nb{sub 3}Sn strand and cable. It is represented by the OST high current RRP Nb{sub 3}Sn strand with 108/127 configuration. The effects of Rutherford cabling to both type strands are explained and the inherent problem of the Nb{sub 3}Sn strand is discussed. Also the test results of two representative small racetrack magnets are compared from the stand point of Ic values, and training. The maximum current density of the Nb{sub 3}Al strands is still smaller than that of the Nb{sub 3}Sn strands, but if we take into account of the stress-strain characteristics, Nb{sub 3}Al strands become somewhat favorable in some applications.

Design Modifications, Fabrication and Test of HFDB-03 Racetrack Magnet Wound with Pre-Reacted Nb3Sn Rutherford Cable

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Barzi, E.; Bhashyam, S.; Carcagno, R.; Feher, S.; Imbasciati, L.; Lamm, M.; Pischalnikov, Y.; Tartaglia, M.; Tompkins, J.; Zlobin, A.V.

2004-01-01

A 10 T racetrack magnet (HFDB-03) wound with pre-reacted Nb3Sn Rutherford cable has been fabricated and tested at Fermilab. This magnet is the third one in a proof-of-principle series for the use of the React-and-Wind technology in common-coil dipole magnets for future accelerators. It consists of two flat racetrack coils (28 turns each) separated by 5 mm. The maximum field on the coil, at the short sample limit of 16530 A, is 10 tesla. The cable has 41 strands with 0.7 mm diameter and the minimum bend radius in the magnet ends is 90 mm. The predecessor of this magnet (HFDB-02) reached 78 % of the short sample limit at 7.7 T. The mechanical design was improved and the fabrication procedure was slightly modified in order to address possible causes of limitation. In this paper we present the mechanical design and analysis of HFDB-03, the modifications to the fabrication procedure and the test results

Production and qualification of 40 km of Al-stabilized NbTi cable for the ATLAS experiment at CERN

CERN Document Server

Baccaglioni, G; Cartegni, G C; Horváth, I L; Neuenschwander, J; Pedrini, D; Rossi, L; Volpini, G

2002-01-01

The production of the conductor for the superconducting toroids of the ATLAS experiment at LHC (CERN) is now in progress. The toroid system, composed of one barrel toroid (BT) and two end cap toroids (ECTs), exploits aluminum-clad Rutherford-type NbTi conductors of large size (57 * 12 mm for BT, 42 * 12 mm for ECTs) and high critical current (Ic) (58 kA for BT and 60 kA for ECTs @ 4.2 K, 5 T). Some 55 km of conductor are required for the BT and 26 km for the ECTs, respectively. An Italian-Swiss (ETH Zurich and INFN) consortium is in charge of the delivery of half of the whole amount. This paper describes the results of this production with particular emphasis to the quality control system developed to monitor the production with both on-line controls and the post-production quality assessment protocols. The main result is the confirmation that the technologies selected and the whole process are reliable and reproducible over large production quantities. The overall degradation due to the cabling and the co-ex...

Effect of transverse loads up to 300 MPa on the critical currents of Nb3Sn cables

NARCIS (Netherlands)

Boschman, H.; Verweij, A.P.; Verweij, A.P.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.; van de Klundert, L.J.M.; van de Klundert, L.J.M.

1991-01-01

In the framework of the development of an experimental 10-T Nb3Sn dipole coil for the LHC (Large Hadron Collider) at CERN, the effects of transverse stress on Rutherford-type Nb3Sn cable were investigated. For this purpose a special facility was designed and put into operation in which the

Design, processing, and properties of Bi 2212\\/Ag Rutherford cables

CERN Document Server

Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R; Sokolowski, R S; Aoki, Y; Hasegawa, T

1999-01-01

In a program intended to explore the use of high temperature superconducting (HTSC) cables in high field synchrotron dipole magnets model Bi:2212/Ag Rutherford cables were designed bearing in mind the needs for mechanical integrity, relatively high tensile strength, and low coupling losses. To satisfy these needs a core-type cable design was selected and a readily available heat-resistant core material acquired. Cables were wound for critical current- and AC loss measurement. Both winding-induced (mechanical) and core-induced (chemical) critical current degradation was examined. Interstrand coupling loss was measured calorimetrically on model cable samples with bare- and oxide-coated cores. From the results it was predicted that the losses of full-scale Bi:2212/Ag-wound LHC-type Rutherford cables would fall close to the acceptability range for the windings of high-field accelerator dipoles. (10 refs).

Comparing Thermal Stability of NbTi and Nb$_3$Sn Wires

CERN Document Server

Breschi, M; Bottura, L; Devred, A; Trillaud, F

2009-01-01

The investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and Nb$_{3}$Sn wires in pool boiling Helium I. A comparison of the quench behavior of two typical NbTi and Nb$_{3}$Sn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and Nb$_{3}$Sn wires are reported and analyzed. It is shown that the Nb$_{3}$Sn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operation current and pulse duration and magnetic field. It is shown that the Nb$_{3}$Sn wire exhibits a ‘kink’ of the quench energy ...

Quench tests of Nb3Al small racetrack magnets

International Nuclear Information System (INIS)

Yamada, R.; Kikuchi, A.; Tartaglia, Michael Albert; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Kotelnikov, S.; Lamm, Michael J.; Fermilab; NIMC, Tsukuba; KEK, Tsukuba

2007-01-01

Two Cu stabilized Nb3Al strands, F1 (Nb matrixed) and F3 (Ta matrixed), have been made at NIMS and their Rutherford cables were made at Fermilab in collaboration with NIMS. A Small Race-track magnet using F1 Rutherford cable, the first Nb3Al dipole magnet in the world, was constructed and tested to full current at Fermilab. This magnet was tested extensively to full short sample data and its quench characteristics were studied and reported. The 3-D magnetic field calculation was done with ANSYS to find the peak field. The quench characteristics of the magnet are explained with the characteristics of the Nb3Al strand and Rutherford cable. The other Small Race-track magnet using Ta matrixed F3 strand was constructed and will be tested in the near future. The advantages and disadvantages of these Nb3Al cables are discussed

Quench tests of Nb3Al small racetrack magnets

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Kikuchi, A.; Tartaglia, Michael Albert; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Kotelnikov, S.; Lamm, Michael J.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2007-08-01

Two Cu stabilized Nb3Al strands, F1 (Nb matrixed) and F3 (Ta matrixed), have been made at NIMS and their Rutherford cables were made at Fermilab in collaboration with NIMS. A Small Race-track magnet using F1 Rutherford cable, the first Nb3Al dipole magnet in the world, was constructed and tested to full current at Fermilab. This magnet was tested extensively to full short sample data and its quench characteristics were studied and reported. The 3-D magnetic field calculation was done with ANSYS to find the peak field. The quench characteristics of the magnet are explained with the characteristics of the Nb3Al strand and Rutherford cable. The other Small Race-track magnet using Ta matrixed F3 strand was constructed and will be tested in the near future. The advantages and disadvantages of these Nb3Al cables are discussed.

The effect of transverse loads up to 300 MPa on the critical currents of Nb3Sn cables

International Nuclear Information System (INIS)

Boschman, H.; Verweij, A.P.; Wessel, S.; ten Kate, H.H.J.; van de Klundert, L.J.M.

1991-01-01

In the framework of the development of an experimental 10 T Nb 3 Sn dipole coil for the LHC at CERN the effects of transverse stress on Rutherford type of Nb 3 Sn cables have been investigated. For this purpose a special facility was designed and taken into operation in which the voltage-current behavior of short pieces of Nb 3 Sn cables can be investigated in a background field up to 11 T and an applied stress of 300 MPa. The repulsive Lorentz force of 250 kN, generated by a set of superconducting coils, is used to impress the cable over an area of 20 x 42 mm 2 maximum, in presence of a transport current up to 40 kA. In this paper the testing equipment is described and the first results of the observed critical current degradation of two Nb 3 Sn cables are discussed

V-I transition and n-value of multifilamentary LTS and HTS wires and cables

International Nuclear Information System (INIS)

Ghosh, Arup K.

2004-01-01

For low T c multifilamentary conductors like NbTi and Nb 3 Sn, the V-I transition to the normal state is typically quantified by the parameter, n, defined by (ρ/ρ c )=(I/I c ) n . For NbTi, this parameterization has been very useful in the development of high J c wires, where the n-value is regarded as an index of the filament quality. In copper-matrix wires with undistorted filaments, the n-value at 5 T is ∼40-60, and drops monotonically with increasing field. However, n can vary significantly in conductors with higher resistivity matrices and those with a low copper fraction. Usually high n-values are associated with unstable resistive behavior and premature quenching. The n-value in NbTi Rutherford cables, when compared to that in the wires is useful in evaluating cabling degradation of the critical current due to compaction at the edges of the cable. In Nb 3 Sn wires, n-value has been a less useful tool, since often the resistive transition shows small voltages ∼ a few μV prior to quenching. However, in 'well behaved' wires, n is ∼30-40 at 12 T and also shows a monotonic behavior with field. Strain induced I c degradation in these wires is usually associated with lower n-values. For high T c multifilamentary wires and tapes, a similar power law often describes the resistive transition. At 4.2 K, Bi-2223 tapes as well as Bi-2212 wires exhibit n-values ∼15-20. In either case, n does not change appreciably with field. Rutherford cables of Bi-2212 wire show lower values of n than the virgin wire

9.1-T iron-free Nb-Ti dipole magnet with pancake windings

International Nuclear Information System (INIS)

Gilbert, W.; Caspi, S.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J.; Schafer, R.; Taylor, C.; Wolgast, R.

1983-03-01

An eight-pancake Nb-Ti dipole magnet, with bent up ends, called D-108B has been built and tested. This magnet is a Nb-Ti version of a Nb 3 Sn magnet designed to produce a 10-tesla dipole field in a 40 mm diameter aperture. The pancack design is used for the heavy 12,000 ampere Nb 3 Sn cable because of the mechanical difficulty in winding such a heavy cable into the conventional nested cylindrical shell configuration with a 2'' inner winding diameter. The Nb-Ti version operates at 1.8K, in He II, has superconducting cable half as thick as the Nb 3 Sn cable, and operates at half the operating current: 6000 A rather than 12,000 A at 10 tesla. Both magnets are approximately one meter long. D-10B was tested from January 26 to February 2, 1983 and reached short-sample performance in both He I and He II after moderate training. The central field at 4.3K is 7.0 (+- 0.1) tesla, and at 1.8K is 9.1 (+- 0.2) tesla. Ramp rate sensitivity and cyclic heating data were also measured

A 40 kA NbTi cable in conduit conductor for the large poloidal field coils of net

International Nuclear Information System (INIS)

Torossian, A.; Bessette, D.; Turck, B.; Kazimierzak, B.

1990-01-01

The main feature of this cable in conduit design is to separate the manufacture of the full length of the steel conduit (400 m) and of the cable in order to minimize the industrial risk and consequently the cost. A circular cross section for that cable seems to be the most suitable for that purpose: - axisymmetric cabling with full transposition of strands, - cable behaviour independent of the field orientation, - less deformation of subcables, - cross section remains circular when the cable is under tension and makes the slippage of the cable in the conduit easier, - butt welding of 8 m long tubes forming the conduit becomes simpler. The square external shape allows to minimize the amount of insulating material and consequently improves the overall current density of the coil. This conductor is aimed to large poloidal field coils for NET which do not require high field and in that case NbTi seems to be the best choice with regard to reliability and cost but Nb 3 Sn could be used as well. Stainless steel ribbons are inserted between subcables in order to reduce losses induced by the rapid field changes and also to improve the mechanical behaviour of the cable

Study on interstrand coupling losses in Rutherford-type superconducting cables

International Nuclear Information System (INIS)

Lei, Y.Z.; Shintomi, T.; Terashima, A.; Hirabayashi, H.

1993-02-01

Two sets of experimental apparatus for measuring the AC losses in superconducting strands and Rutherford-type cable conductors have been constructed. A few strand samples and a number of compacted cable samples with and without a CuMn matrix have been measured. The hysteresis loss, loss from coupling within strands and loss from coupling between strands in cables have been distinguished from each other. The results show that, even for Rutherford cables without any soldering and coating, their AC losses may be quite different from each other due to the variation of the interstrand coupling loss. For cables without a CuMn matrix, interstrand coupling loss increases nearly according to a geometrical series with an increase of curing temperature simulating coil fabrication. However, cables with the CuMn matrix show a relatively small curing temperature dependence. For most of the samples, losses do not show any evident dependence on the mechanical pressure. Interstrand resistances in one of these cables have also been measured; the results indicate that the tendency for a decrease in the interstrand resistances is consistent with the results of AC loss measurements. (author)

A 9.1-T iron-free Nb- Ti dipole magnet with pancake windings

International Nuclear Information System (INIS)

Gilbert, W.; Caspi, S.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J.; Schafer, R.; Taylor, C.; Wolgast, R.

1983-01-01

An eight-pancake Nb-Ti dipole magnet with bent-up ends and called D-10B has been built and tested. This magnet is a Nb-Ti version of a Nb 3 Sn magnet designed to produce a 10-tesla dipole field in a 40 mm diameter aperture. The pancake design is used for the heavy 12,000 ampere Nb 3 Sn cable because of the mechanical difficulty in winding such a heavy cable into the conventional nested cylindrical shell configuration with a 2'' inner winding diameter. The Nb-Ti version operates at 1.8 K in helium II, has superconducting cable half as thick as the Nb 3 Sn cable, and operates at half the current (6,000 amperes) at 10 tesla. Both magnets are approximately one meter long. D-10B was tested from January 26 to February 2, 1983, and reached short-sample performance in both helium I and helium II after moderate training. The central field at 4.3 K is 7.0 tesla and at 1.8 K is 9.1 tesla. Ramp rate sensitivity and cyclic heating data were also measured

Comparing the thermal stability of NbTi and Nb3Sn wires

International Nuclear Information System (INIS)

Breschi, M; Trevisani, L; Bottura, L; Devred, A; Trillaud, F

2009-01-01

The investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and Nb 3 Sn wires in pool boiling helium I. A comparison of the quench behavior of two typical NbTi and Nb 3 Sn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and Nb 3 Sn wires are reported and analyzed. It is shown that the Nb 3 Sn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared by considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operating current, pulse duration, and magnetic field. It is shown that the Nb 3 Sn wire exhibits a 'kink' of the quench energy versus current curve that makes the quench energy of Nb 3 Sn lower than that of NbTi at some intermediate current levels. Both the qualitative differences of the voltage traces and the different behaviors of quench energies and velocities are interpreted through a coupled electromagnetic-thermal model, with special emphasis on the detailed description of heat exchange with liquid helium.

RHQT Nb3Al 15-Tesla magnet design study

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2005-09-01

Feasibility study of 15-Tesla dipole magnets wound with a new copper stabilized RHQT Nb{sub 3}Al Rutherford cable is presented. A new practical long copper stabilized RHQT Nb{sub 3}Al strand is presented, which is being developed and manufactured at the National Institute of Material Science (NIMS) in Japan. It has achieved a non-copper J{sub c} of 1000A/mm{sup 2} at 15 Tesla at 4.2K, with a copper over non-copper ratio of 1.04, and a filament size less than 50 microns. For this design study a short Rutherford cable with 28 Nb{sub 3}Al strands of 1 mm diameter will be fabricated late this year. The cosine theta magnet cross section is designed using ROXIE, and the stress and strain in the coil is estimated and studied with the characteristics of the Nb{sub 3}Al strand. The advantages and disadvantages of the Nb{sub 3}Al cable are compared with the prevailing Nb{sub 3}Sn cable from the point of view of stress-strain, J{sub c}, and possible degradation of stabilizer due to cabling. The Nb{sub 3}Al coil of the magnet, which will be made by wind and react method, has to be heat treated at 800 degree C for 10 hours. As preparation for the 15 Tesla magnet, a series of tests on strand and Rutherford cables are considered.

Low coupling loss core-strengthened Bi 2212\\/Ag Rutherford cables

CERN Document Server

Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R

1999-01-01

In a comprehensive "vertically integrated" program multifilamentary (MF) high temperature superconducting (HTSC) Bi:2212/Ag strand was fabricated using the powder-in-tube process and heat treated in oxygen by a modified standard $9 procedure. The reaction-heat-treatment (HT) was adjusted to maximize critical current (density), I/sub c/ (J /sub c/), as measured in various magnetic fields, B. A series of Rutherford cables was designed, each of which included a $9 metallic (Nichrome-80) core for strengthening and reduction of coupling loss. Prior to cable winding a series of tests examined the possibility of strand "poisoning" by the core during HT. Small model Rutherford cables were wound, $9 and after HT were prepared for I/sub c/(B) measurement and calorimetric measurement of AC loss and hence interstrand contact resistance I/sub c/(B). It was deduced that, if in direct contact with the strand during HT, the core $9 material can degrade the I/sub c/ of the cable; but steps can be taken to eliminate this probl...

Difference in Stability Between Edge and Center in a Rutherford Cable

NARCIS (Netherlands)

Willering, G.P.; Verweij, A.P.; Scheuerlein, C.; den Ouden, A.; ten Kate, Herman H.J.

Keystoned superconducting Rutherford cables are widely used in accelerator magnets like in the LHC at CERN. An essential requirement in the cable design is its stability against local heat releases in the magnet windings originating from for example, strand movement or beam loss. Beam loss is the

Analysis of the quench propagation along Nb$_{3}$Sn Rutherford cables with the THELMA code. Part II: application to the quench longitudinal propagation

CERN Document Server

Manfreda, G.; Bajas, H.; Perez, J.C.

2016-01-01

To improve the technology of the new generation of accelerator magnets, prototypes are being manufactured and tested in several laboratories. In parallel, many numerical analyses are being carried out to predict the magnets behaviour and interpret the experimental results. This paper focuses on the quench propagation velocity, which is a crucial parameter as regards the energy dissipation along the magnet conductor. The THELMA code, originally developed for cable-in-conduit conductors for fusion magnets, has been used to study such quench propagation. To this purpose, new code modules have been added to describe the Rutherford cable geometry, the material non-linear thermal properties and to describe the thermal conduction problem in transient regime. THELMA can describe the Rutherford cable at the strand level, modelling both the electrical and thermal contact resistances between strands and enabling the analysis of the effects of local hot spots and quench heaters. This paper describes the model application...

Development of scaling rules for Rutherford type superconducting cables

International Nuclear Information System (INIS)

Royet, J.M.; Scanlan, R.M.

1991-01-01

During the R and D phase of the Superconducting Supercollider (SSC) program, LBL was responsible for establishing the parameters for cables used in SSC dipole and quadrupole magnets. In addition, LBL has collaborated with Fermi National Accelerator Laboratory on the design and fabrication of a new cable for use in the Low Beta Quadrupoles. As a result of the development work on these and other cables, we have arrived a set of scaling rules which provide guidelines for choosing the parameters for a wide range of superconducting cables. These parameters include strand size, strand number, keystone angle, percent compaction, cable pitch and compacted cable dimensions. In addition, we have defined the tolerance ranges for the key cable manufacturing parameters such as mandrel size and shape, strand tension, and Turkshead temperature control. In this paper, the authors present the results on cables ranging from 8 strands to 36 strands of 0.65mm wire and from 8 strands to 30 strands of 0.8mm wire. The authors use these results to demonstrate the application of the scaling rules for Rutherford-type cable

Development of scaling rules for Rutherford type superconducting cables

International Nuclear Information System (INIS)

Royet, J.M.; Scanlan, R.M.

1990-09-01

During the R ampersand D phase of the Superconducting Supercollider (SSC) program, LBL was responsible for establishing the parameters for cables used in SSC dipole and quadrupole magnets. In addition, the design and fabrication of a new cable for use in the Low Beta Quadrupoles. As a result of the development work on these and other cables, we have arrived a set of scaling rules which provide guidelines for choosing the parameters for a wide range of superconducting cables. These parameters include strand size, strand number, keystone angle, percent compaction, cable pitch and compacted cable dimensions. In addition, we have defined the tolerance ranges for the key cable manufacturing parameters such as mandrel size and shape, stand tension, and Turkshead temperature control. In this paper, we present the results on cables ranging from 8 strands to 36 strands of 0.65mm wire and from 8 strands to 30 strands of 0.8mm wire. We use these results to demonstrate the application of the scaling rules for Rutherford-type cable

Direct measurements of inter-filament resistance in various multi-filamentary superconducting NbTi and Nb3Sn strands

NARCIS (Netherlands)

Zhou, Chao; Miyoshi, Y.; van Lanen, E.P.A.; Dhalle, Marc M.J.; Nijhuis, Arend

2012-01-01

For a proper characterization of multi-filamentary NbTi and Nb3Sn strands and a better understanding of their performance in short sample tests, as well as for increased understanding of inter-strand current redistribution in cabled conductors, a quantitative knowledge of the inter-filament

Cu-Ti Formation in Nb-Ti/Cu Superconducting Strand Monitored by in situ Techniques

CERN Document Server

Pong, I; Pong, Ian; Gerardin, Alexandre; Scheuerlein, Christian; Bottura, Luca

2010-01-01

In order to investigate the high temperature exposure effect on Nb-Ti/Cu superconducting strands, as might be encountered in joining by soldering and in cabling annealing, X-ray diffraction and resistometry measurements were performed in situ during heat treatment, and complemented by conventional metallography, mechanical tests and superconducting properties measurements. Changes of the Nb-Ti nanostructure at temperatures above 300 degrees C are manifested in the degradation of critical current in an applied external magnetic field, although degradation at self field was insignificant up to 400 degrees C for several minutes. Above 500 degrees C, the formation of various Cu-Ti intermetallic compounds, due to Ti diffusion from Nb-Ti into Cu, is detected by in situ XRD albeit not resolvable by SEM-EDS. There is a ductile to brittle transition near 600 degrees C, and liquid formation is observed below 900 degrees C. The formation of Cu-Ti causes a delayed reduction of the residual resistivity ratio (RRR) and adv...

Comparative Study of Heat Transfer from Nb-Ti and Nb$_3$Sn coils to He II

CERN Document Server

La China, M

2008-01-01

In superconducting magnets, the energy deposited or generated in the coil must be evacuated to prevent temperature rise and consequent transition of the superconductor to the resistive state. The main barrier to heat extraction is represented by the electric insulation wrapped around superconducting cables. In the LHC, insulation improvement is a key point in the development of interaction region magnets and injector chain fast-pulsed magnets for luminosity upgrade; the high heat load of these magnets, in fact, is not compatible with the use of current insulation schemes. We review the standard insulation schemes for Nb-Ti and Nb$_{3}$Sn technology from the thermal point of view. We implement, in an analytical model, the strongly nonlinear thermal resistances of the different coil components including the permeability to superfluid helium of Nb-Ti insulations, measured during the LHC main dipole development. We use such a model to compare Nb-Ti and Nb$_{3}$Sn technologies by taking into account their specific...

Comparative study of heat transfer from Nb-Ti and Nb_{3}Sn coils to He II

Directory of Open Access Journals (Sweden)

Marco La China

2008-08-01

Full Text Available In superconducting magnets, the energy deposited or generated in the coil must be evacuated to prevent temperature rise and consequent transition of the superconductor to the resistive state. The main barrier to heat extraction is represented by the electric insulation wrapped around superconducting cables. In the LHC, insulation improvement is a key point in the development of interaction region magnets and injector chain fast-pulsed magnets for luminosity upgrade; the high heat load of these magnets, in fact, is not compatible with the use of current insulation schemes. We review the standard insulation schemes for Nb-Ti and Nb_{3}Sn technology from the thermal point of view. We implement, in an analytical model, the strongly nonlinear thermal resistances of the different coil components including the permeability to superfluid helium of Nb-Ti insulations, measured during the LHC main dipole development. We use such a model to compare Nb-Ti and Nb_{3}Sn technologies by taking into account their specific operating margin in different working conditions. Finally, we propose an insulation scheme to enhance the heat transfer capability of Nb-Ti coils.

Design study of 15-Tesla RHQT Nb3Al block type dipole magnet

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2005-09-01

The design study of the block type 15-Tesla RHQT Nb{sub 3}Al dipole magnet, and its merits over Nb{sub 3}Sn magnets are presented. The copper stabilized RHQT Nb{sub 3}Al strand is now becoming commercially available for the application to the accelerator magnets. A 1 mm diameter RHQT Nb{sub 3}Al strand with filament size about 50 {mu}, non-copper Jc about 1000 A/mm{sup 2} at 15 Tesla at 4.2K, copper ratio of 50%, can now be produced over several hundred meters. The stress and strain characteristics of the Nb{sub 3}Al strand are superior to the Nb{sub 3}Sn strand. Another advantage is that it can tolerate a longitudinal strain up to 0.55%. The RHQT Nb{sub 3}Al Rutherford cable will have less chance of contamination of the stabilizer, compared to Nb{sub 3}Sn cable. These characteristics of the RHQT Nb{sub 3}Al will be beneficial for designing and producing 15-Tesla dipole magnets. An example 15-Tesla magnet cross section, utilizing the RHQT Nb{sub 3}Sn strand is presented. A systematic investigation on RHQT Nb{sub 3}Al strands, its Rutherford cables, and building a small racetrack magnet for cable testing are proposed.

Experimental results of current distribution in Rutherford-type LHC cables

CERN Document Server

Verweij, A P

2000-01-01

Current distribution among the wires of multi-strand superconducting cables is an important item for accelerator magnets. A non-uniform distribution could cause additional field distortions in the magnet bore and can as well be one of the reasons of premature quenching. Since two years electrical measurements on superconducting Rutherford-type cables are performed at CERN as part of the reception tests for the Large Hadron Collider (LHC). Cable samples of 2.4 m length are tested at currents up to 32 kA, temperatures around 1.9 and 4.3 K, and fields up to 10 T, applied perpendicularly as well as parallel to the broad face of the cable. Last year, an array of 24 Hall probes was installed in the test set-up in order to measure the self-field of the cable samples along one cable pitch. Each of the probes measures the local field generated by the current in the strands close by, and the results of the all probes reflect therefore the distribution of the strand currents. Experiments are done varying the applied fie...

Performance of Nb3Sn RRP strands and cables based on a 108/127 stack design

International Nuclear Information System (INIS)

Barzi, E.; Ambrosio, G.; Andreev, N.; Bossert, R.; Carcagno, R.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Pishalnikov, Y.; Sylvester, C.; Tartaglia, M.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; Field, M.; Hong, S.; Parrell, J.; Zhang, Y.

2006-01-01

The high performance Nb 3 Sn strand produced by Oxford Superconducting Technology (OST) with the Restack Rod Process (RRP) is presently considered as a baseline conductor for the Fermilab's accelerator magnet R and D program. To improve the strand stability in the current and field range expected in magnet models, the number of subelements in the strand was increased by a factor of two (from 54 to 108), which resulted in a smaller effective filament size. The performance of the 1.0 and 0.7 mm strands of this design was studied using virgin and deformed strand samples. 27-strand Rutherford cables made of 1 mm strand were also tested using a superconducting transformer, small racetrack and 1-m shell-type dipole coils. This paper presents the RRP strand and cable parameters, and reports the results of strand, cable and coil testing

Performance of Nb3Sn RRP strands and cables based on a 108/127 stack design

Energy Technology Data Exchange (ETDEWEB)

Barzi, E.; Ambrosio, G.; Andreev, N.; Bossert, R.; Carcagno, R.; Feher, S.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; /Fermilab /Oxford Supercond. Tech., Carteret

2006-08-01

The high performance Nb{sub 3}Sn strand produced by Oxford Superconducting Technology (OST) with the Restack Rod Process (RRP) is presently considered as a baseline conductor for the Fermilab's accelerator magnet R&D program. To improve the strand stability in the current and field range expected in magnet models, the number of subelements in the strand was increased by a factor of two (from 54 to 108), which resulted in a smaller effective filament size. The performance of the 1.0 and 0.7 mm strands of this design was studied using virgin and deformed strand samples. 27-strand Rutherford cables made of 1 mm strand were also tested using a superconducting transformer, small racetrack and 1-m shell-type dipole coils. This paper presents the RRP strand and cable parameters, and reports the results of strand, cable and coil testing.

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES

International Nuclear Information System (INIS)

Kawagoe, A.; Kawabata, Y.; Sumiyoshi, F.; Nagaya, S.; Hirano, N.

2006-01-01

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES coils were evaluated from a comparison between measured data and 2D-FEM analyses on interstrand coupling losses in these cables. The cables were composed of 30 non-twisted Bi-2212 strands with a diameter of 0.81 mm and a cable twist pitch of 90 mm. Three samples were measured; one of them had NiCr cores and the others had no cores. One of the latter two samples repeatedly experienced bending. The interstrand coupling losses were measured in liquid helium for the straight samples under transverse ac ripple magnetic fields superposed on dc bias magnetic fields. The transverse magnetic field was applied to the samples in directions both perpendicular and parallel to the flat face of the cable. The effect of the bending on the interstrand coupling losses could be neglected for the non-cored samples. The interstrand coupling losses of NiCr cored sample decreased by about 30% compared with the non-cored samples, in case the direction of the transverse magnetic fields applied to the cable is perpendicular to the flat face of the cable. Using these results and 2D-FEM analyses, taking into account that interstrand contact conditions vary from the center to the edge in the cross-section of cables, gave us the conclusion that the between side-by-side strands contact with metallurgical bond only in both edges of the cables

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES

Science.gov (United States)

Kawagoe, A.; Kawabata, Y.; Sumiyoshi, F.; Nagaya, S.; Hirano, N.

2006-10-01

Interstrand contact resistances of Bi-2212 Rutherford cables for SMES coils were evaluated from a comparison between measured data and 2D-FEM analyses on interstrand coupling losses in these cables. The cables were composed of 30 non-twisted Bi-2212 strands with a diameter of 0.81 mm and a cable twist pitch of 90 mm. Three samples were measured; one of them had NiCr cores and the others had no cores. One of the latter two samples repeatedly experienced bending. The interstrand coupling losses were measured in liquid helium for the straight samples under transverse ac ripple magnetic fields superposed on dc bias magnetic fields. The transverse magnetic field was applied to the samples in directions both perpendicular and parallel to the flat face of the cable. The effect of the bending on the interstrand coupling losses could be neglected for the non-cored samples. The interstrand coupling losses of NiCr cored sample decreased by about 30% compared with the non-cored samples, in case the direction of the transverse magnetic fields applied to the cable is perpendicular to the flat face of the cable. Using these results and 2D-FEM analyses, taking into account that interstrand contact conditions vary from the center to the edge in the cross-section of cables, gave us the conclusion that the between side-by-side strands contact with metallurgical bond only in both edges of the cables.

Preparation, composition, and solid state investigations of TiN, ZrN, NbN, and compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN

International Nuclear Information System (INIS)

Christensen, A.N.; Fregerslev, S.

1977-01-01

Single crystals of the cubic phases TiN, ZrN, delta-NbN and of compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN were obtained by zone melting, zone annealing and annealing of the metal carbides in nitrogen gas of 2 MPa. Single crystals of the tetragonal phase gamma-NbN were obtained in a similar way by annealing of niobium. The nitrides are non-stochiometric. TiN was obtained in the composition range TiNsub(0.99) to TiNsub(0.50), ZrN in the range ZrNsub(1.00) to ZrNsub(0.63), and in niobium nitrides were obtained in the composition range NbNsub(0.90) to NbNsub(0.69). The compounds from the pseudobinary systems have up to 35% vacant sites in the nitrogen-carbon sublattice. TiN and ZrN have only vacant sites in the nitrogen sublattice. A correlation is found between the unit cell parameters for titanium nitride and zirconium nitride and the nitrogen-metal ratios. (orig.) [de

Stability analysis of NbTi-Ta-based high field conductor cooled by pool boiling below 4 K

International Nuclear Information System (INIS)

Chen, W.Y.; Alcorn, J.S.; Hsu, Y.H.; Purcell, J.R.

1980-09-01

Stability analysis has been performed for cabled NbTi-Ta-based superconductors intended for the high field (12 T) toroidal field coils for a large scale tokamak device such as ETF. Ternary NbTi-Ta was selected as the superconductor because of its superior critical current density at high field as compared to the binary alloy NbTi. The operating temperature was chosen to be 2.5 K or below to optimize the performance of the superconductor. A cabled conductor was selected to minimize the pulsed field losses. The conductor is cooled by pool boiling in a subcooled (approx. 2.5 K, 0.25 atm) bath, or in a superfluid helium (He-II) bath (approx. 1.8 K, 0.02 atm). The analysis was based on numerically simulating the evolution of a normal zone in the conductor. Appropriate superconductor properties and heat transfer characteristics were utilized in the simulation

In situ NiTi/Nb(Ti) composite

International Nuclear Information System (INIS)

Jiang, Daqiang; Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

2013-01-01

Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength

Solid solution cermet: (Ti,Nb)(CN)-Ni cermet.

Science.gov (United States)

Kwon, Hanjung; Jung, Sun-A

2014-11-01

Solid solution powders without W, (Ti,Nb)(CN) powders with a B1 structure (NaCl like), were synthesized by high energy milling and carbothermal reduction in nitrogen. The range of molar ratios of Ti/Nb for forming complete (Ti,Nb)(CN) phase was broader than that of Ti/W for the (Ti,W)(CN) phase because carbide or carbonitride of Nb had a B1 crystal structure identical to Ti(CN) while WC had a hexagonal crystal structure. The results revealed that the hardness of (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,W)(CN)-Ni cermets. The lower density of the (Ti,Nb)(CN) powder contributed to the higher hardness compared to (Ti,W)(CN) because the volumetric ratio of (Ti,Nb)(CN) in the (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,Nb)(CN) in the (Ti,W)(CN)-Ni cermets at the same weight ratio of Ni. Additionally, it was assumed that intrinsic the properties of (Ti,Nb)(CN) could also be the cause for the high hardness of the (Ti,Nb)(CN)-Ni cermets.

Biological Properties of Ti-Nb-Zr-O Nanostructures Grown on Ti35Nb5Zr Alloy

Directory of Open Access Journals (Sweden)

Zhaohui Li

2012-01-01

Full Text Available Surface modification of low modulus implant alloys with oxide nanostructures is one of the important ways to achieve favorable biological behaviors. In the present work, amorphous Ti-Nb-Zr-O nanostructures were grown on a peak-aged Ti35Nb5Zr alloy through anodization. Biological properties of the Ti-Nb-Zr-O nanostructures were investigated through in vitro bioactivity testings, stem cell interactions, and drug release experiments. The Ti-Nb-Zr-O nanostructures demonstrated a good capability of inducing apatite formation after immersion in simulated body fluids (SBFs. Drug delivery experiment based on gentamicin and the Ti-Nb-Zr-O nanostructures indicated that a high drug loading content could result in a prolonged release process and a higher quantity of drug residues in the oxide nanostructures after drug release. Quick stem cell adhesion and spreading, as well as fast formation of extracellular matrix materials on the surfaces of the Ti-Nb-Zr-O nanostructures, were found. These findings make it possible to further explore the biomedical applications of the Ti-Nb-Zr-O nanostructure modified alloys especially clinical operation of orthopaedics by utilizing the nanostructures-based drug-release system.

Enhanced flux creep in Nb-Ti superconductors after an increase in temperature

International Nuclear Information System (INIS)

Cross, R.W.; Goldfarb, R.B.

1991-01-01

The magnetic fields of Superconducting Super Collider (SSC) dipole magnets change with time when the magnets are operated at constant current. The decay of the field is thought to be a consequence of flux creep in the Nb-Ti filaments in the superconducting cables. However, measured magnetic relaxation of small samples of SSC cable as a function of time is unlike the large decays that are observed in the fields of the actual magnets. We have made relaxation measurements on sample SSC conductors at 3.5 and 4.0 K after field cycling. The decay at both temperatures was 2.8% in 50 min. However, the relaxation measured after a temperature increase from 3.5 to 4.0 K was 4.8% in 50 min. A likely reason for the greater magnetization decay is that, after an increase in temperature, the Nb-Ti is in a supercritical state, with shielding currents flowing at a density greater than the new critical current density. This causes enhanced flux creep. We suggest that a small temperature rise during the operation of SSC magnets may contribute to the unexpectedly large magnetic field decay

Test results of the first 50 kA NbTi full size sample for ITER

International Nuclear Information System (INIS)

Ciazynski, D.; Zani, L.; Huber, S.; Stepanov, B.; Karlemo, B.

2003-01-01

Within the framework of the research studies for the International Thermonuclear Experimental Reactor (ITER) project, the first full size NbTi conductor sample was fabricated in industry and tested in the SULTAN facility (Villigen, Switzerland). This sample (PF-FSJS), which is relevant to the Poloidal Field coils of ITER, is composed of two parallel straight bars of conductor, connected at bottom through a joint designed according to the Cea twin-box concept. The two conductor legs are identical except for the use of different strands: a nickel plated NbTi strand with a pure copper matrix in one leg, and a bare NbTi strand with copper matrix and internal CuNi barrier in the other leg. The two conductors and the joint were extensively tested regarding DC (direct current) and AC (alternative current) properties. This paper reports on the tests results and analysis, stressing the differences between the two conductor legs and discussing the impact of the test results on the ITER design criteria for conductor and joint. While joint DC resistance, conductors and joint AC losses, fulfilled the ITER requirements, neither conductor could reach its current sharing temperature at relevant ITER currents, due to instabilities. Although the drop in temperature is slight for the CuNi strand cable, it is more significant for the Ni plated strand cable. (authors)

Diffusion behavior in the films of Nb-Ti systems

International Nuclear Information System (INIS)

Yoshitake, Michiko; Yoshihara, Kazuhiro

1990-01-01

The diffusion behavior of substrate element into a deposited film was investigated. The observed systems were a Nb film/Ti substrate and a Ti film/Nb substrate. When the Nb film/Ti substrate was heated in a vacuum, Ti diffused very rapidly in the Nb film. The pre-exponential factor of the diffusion constant of Ti in the Nb film was 5.6x10 -2 m 2 s -1 , and the activation energy was 220 kJmol -1 . The observed activation energy is about 60% of that of Ti in the bulk Nb. On the other hand, when the Ti film/Nb substrate was heated in a vacuum, Nb did not diffuse so rapidly. Titanium diffused through the Nb film rapidly and was concentrated on the surface of the Nb film. The chemical state of the concentrated Ti was metallic, and neither titanium oxides nor titanium carbide was observed. Therefore, the driving force of the rapid diffusion of Ti in the Nb film is considered as the reduction of the surface energy of Nb film. The difference in the diffusion behavior between Ti through the Nb film and Nb through the Ti film is explained supposing that the segregation of Ti reduces the surface energy of the Nb film but the segregation of Nb does not reduce the surface energy of the Ti film. After heating of the Nb film/Ti substrate for a long time, a new phase was formed at the interface between the Nb film and the Ti substrate. The chemical composition of the new phase is about 50% of Ti and 50% of Nb. This phase has not been reported in the phase diagram of the bulk Ti-Nb system. The surface area of the Nb film is considered to be quite large, so the contribution of surface energy to the thermodynamic state of the Nb film cannot be neglected. Therefore, the chemical potential of the film is different from that of the bulk. Then, the new phase, which does not exist in the phase diagram of the bulk system, is formed by an interaction of the films. (author)

Anodic Fabrication of Ti-Nb-Zr-O Nanotube Arrays

Directory of Open Access Journals (Sweden)

Qiang Liu

2014-01-01

Full Text Available Highly ordered Ti-Nb-Zr-O nanotube arrays were fabricated through pulse anodic oxidation of Ti-Nb-Zr alloy in 1 M NaH2PO4 containing 0.5 wt% HF electrolytes. The effect of anodization parameters and Zr content on the microstructure and composition of Ti-Nb-Zr-O nanotubes was investigated using a scanning electron microscope equipped with energy dispersive X-ray analysis. It was found that length of the Ti-Nb-Zr-O nanotubes increased with increase of Zr contents. The diameter and the length of Ti-Nb-Zr-O nanotubes could be controlled by pulse voltage. XRD analysis of Ti-Nb-Zr-O samples annealed at 500°C in air indicated that the (101 diffraction peaks shifted from 25.78° to 25.05° for annealed Ti-Nb-Zr-O samples with different Zr contents because of larger lattice parameter of Ti-Nb-Zr-O compared to that of undoped TiO2.

Niobium alloys production with elements of high steam pressure and high ductilidate Nb46,5%Ti, Nb 1%Zr, Nb 1%Ti and Nb20% Ta

International Nuclear Information System (INIS)

Pinatti, D.G.; Baldan, C.A.; Dainesi, C.R.; Sandim, H.R.Z.

1988-01-01

The melting technology of niobium alloys with high ductilidade and high steam pressure, having the Ti, Zr and Ta as alloying elements is described. The electron beam technique for production of Nb 46,5%Ti, Nb 1%Zr and Nb 20%Ta alloys is analysed, aiming a product with high grade and low cost. (C.G.C.) [pt

Effect of Nb on the Microstructure, Mechanical Properties, Corrosion Behavior, and Cytotoxicity of Ti-Nb Alloys.

Science.gov (United States)

Han, Mi-Kyung; Kim, Jai-Youl; Hwang, Moon-Jin; Song, Ho-Jun; Park, Yeong-Joon

2015-09-09

In this paper, the effects of Nb addition (5-20 wt %) on the microstructure, mechanical properties, corrosion behavior, and cytotoxicity of Ti-Nb alloys were investigated with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xNb alloys. Phase/microstructure was analyzed using X-ray diffraction (XRD), SEM, and TEM. The results indicated that the Ti-xNb alloys (x = 10, 15, and 20 wt %) were mainly composed of α + β phases with precipitation of the isothermal ω phase. The volume percentage of the ω phase increased with increasing Nb content. We also investigated the effects of the alloying element Nb on the mechanical properties (including Vickers hardness and elastic modulus), oxidation protection ability, and corrosion behavior of Ti-xNb binary alloys. The mechanical properties and corrosion behavior of Ti-xNb alloys were found to be sensitive to Nb content. These experimental results indicated that the addition of Nb contributed to the hardening of cp-Ti and to the improvement of its oxidation resistance. Electrochemical experiments showed that the Ti-xNb alloys exhibited superior corrosion resistance to that of cp-Ti. The cytotoxicities of the Ti-xNb alloys were similar to that of pure titanium.

Comparison of the costs of superconducting accelerator dipoles using NbTi, Nb3Sn and NbTiTa

International Nuclear Information System (INIS)

Hassenzahl, W.

1981-03-01

The present study, which is based on the assumption that future, high-energy accelerators will use superconductors, is a comparison of the costs of 5 to 12 Tesla NbTi, Nb 3 S/sub n/, and NbTiTa accelerator magnets operating at 4.2 K or 1.8 K. The object of this evaluation is not to determine the actual cost of future accelerators, rather, its purpose is to provide some rationale for research on the next generation of superconducting accelerator magnets. Thus, though the actual costs of accelerator magnets may be different from those given here, the comparisons are valid

IR emission and electrical conductivity of Nd/Nb-codoped TiO{sub x} (1.5 < x < 2) thin films grown by pulsed-laser deposition

Energy Technology Data Exchange (ETDEWEB)

Tchiffo-Tameko, C.; Cachoncinlle, C. [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France); Perriere, J. [Sorbonne Universités, UPMC Université Paris 06, UMR 7588, INSP, 75005 Paris (France); CNRS, UMR 7588, INSP, 75005 Paris (France); Nistor, M. [NILPRP, L 22 P.O. Box MG-36, 77125 Bucharest-Magurele (Romania); Petit, A.; Aubry, O. [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France); Pérez Casero, R. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Millon, E., E-mail: eric.millon@univ-orleans.fr [GREMI, UMR 7344 CNRS-Université Orléans, 45067 Orléans Cedex 2 (France)

2016-12-15

Highlights: • Nd/Nb-codoped TiO{sub 2} PLD films are electrically insulating and transparent in the UV visible NIR spectral domain. • Nd/Nb-codoped oxygen deficient TiO{sub x} (x ≈ 1.5) films are conductive and absorbent. • IR emission of Nd{sup 3+} in codoped TiO{sub x} films is quenched due to oxygen deficiency. • High Nb-doping rate decreases the IR emission of Nd{sup 3+} in Nd/Nb-codoped TiO{sub 2} films. - Abstract: The effect of the co-doping with Nd and Nb on electrical and optical properties of TiO{sub x} films is reported. The role of oxygen vacancies on the physical properties is also evidenced. The films are grown by pulsed-laser deposition onto (001) sapphire and (100) silicon substrates. The substrate temperature was fixed at 700 °C. To obtain either stoichiometric (TiO{sub 2}) or highly oxygen deficient (TiO{sub x} with x < 1.6) thin films, the oxygen partial pressure was adjusted at 10{sup −1} and 10{sup −6} mbar, respectively. 1%Nd-1%Nb, 1%Nd-5%Nb and 5%Nd-1%Nb co-doped TiO{sub 2} were used as bulk ceramic target. Composition, structural and morphological properties of films determined by Rutherford backscattering spectroscopy, X-ray diffraction and scanning electron microscopy, are correlated to their optical (UV–vis transmission and photoluminescence) and electrical properties (resistivity at room temperature). The most intense Nd{sup 3+} emission in the IR domain is obtained for stoichiometric films. Codoping Nd-TiO{sub x} films by Nb{sup 5+} ions is found to decrease the photoluminescence efficiency. The oxygen pressure during the growth allows to tune the optical and electrical properties: insulating and highly transparent (80% in the visible range) Nd/Nb codoped TiO{sub 2} films are obtained at high oxygen pressure, while conductive and absorbent films are grown under low oxygen pressure (10{sup −6} mbar).

Creep behavior of Ti3Al-Nb intermetallic alloys

International Nuclear Information System (INIS)

Yu, T.H.; Yue, W.J.; Koo, C.H.

1997-01-01

It is well known that Ti 3 Al-Nb alloys are potential materials for aerospace applications. The creep property is an important consideration when materials are used at high temperature. In this article, the effect of microstructure of Ti-25Al-10Nb alloy on the creep property was investigated, and the creep property of Ti-25Al-10Nb alloy modified by small addition of silicon 0.2 at.% or carbon 0.1 at.% was observed. The alloy with the addition of molybdenum to replace part of niobium 2 at.% was also studied. The experimental results show that the furnace-cooled Ti-25Al-10Nb alloy has superior creep resistance to the air-cooled Ti-25Al-10Nb alloy at 200 MPa, but exhibits poor creep resistance at 250 MPa or above. Small addition of silicon to the Ti-25Al-10Nb alloy may increase creep resistance. Small addition of carbon to the Ti-25Al-10Nb alloy may reduce creep resistance but raise rupture strain. Molybdenum is the most effective alloying element to increase creep resistance for the Ti-25Al-10Nb alloy. The creep mechanism of Ti-25Al-10Nb alloy is governed by dislocation climb. (orig.)

Current distribution inside Rutherford-type superconducting cables and impact on performance of LHC dipoles

CERN Document Server

Schreiner, T

2002-01-01

The windings of high--field superconducting accelerator magnets are usually made of Rutherford--type cables. The magnetic field distribution along the axis of such magnets exhibits a periodic modulation with a wavelength equal to the twist pitch length of the cable used in the winding. Such a Periodic Field Pattern (PFP) has already been observed in number of superconducting accelerator magnets. Additional unbalanced currents in individual strands of the cable appear to be causing this effect. The present thesis describes the investigation of the PFPs performed with a Hall probes array inserted inside the aperture of the LHC superconducting dipoles, both in the small--scale model magnets with a length of one meter and in full--scale prototypes and pre--series magnets with fifteen meters of length. The amplitude and the time dependence of this periodic field oscillation have been studied as a function of the magnet current history. One of the main parameters influencing the properties of the PFP is the cross--...

The optimization of NbTi-Nb/sub 3/Sn high field superconducting magnet used for physics experiments

International Nuclear Information System (INIS)

Han, B.; Han, S.; Feng, Z.X.

1989-01-01

The approach to the optimum cost design of multigraded NbTi-Nb/sub 3/Sn high field superconducting magnet is proposed. Investigation shows that by reasonably choosing the contribution of NbTi and Nb/sub 3/Sn coils to the central field required and properly increasing the parameters β of both NbTi and Nb/sub 2/Sn coils, the optimum cost design of the NbTi-Nb/sub 3/Sn solenoid magnet can be obtained. This is the base on which the minimum cost design of multi-graded NbTi-Nb/sub 3/Sn high field superconducting magnet is reached. As an example, a calculation of a 14T three graded NbT-Nb/sub 3/Sn superconducting magnet with a bore of 31mm in diameter is given

Study of Nb{sub 3}Sn cables for superconducting quadrupoles; Etude de cables Nb{sub 3}Sn pour quadripoles supraconducteurs

Energy Technology Data Exchange (ETDEWEB)

Otmani, R

1999-10-01

In particle physics, the quest for higher energies may be satisfied by the use of niobium-tin superconducting magnets. Such magnets are made of Rutherford type cables which are wound from superconducting strands. The strands are made by the 'internal tin' method. The aim of this study is to determine the main parameters for the fabrication of a quadrupole. The two main requirements the cable must fulfill are high critical current and low losses. The main parameters were determined from different measurements and models. Thus, the key parameters for the current transport capacity are the number and the diameter of the filaments, the number of sub-elements, the surface of superconductor and the copper-to-non-copper ratio. For the hysteresis losses, the main parameters appear to be the effective filament diameter and the spacing of the filaments. For intra-strand losses, the main parameters appear to be the filaments' diameter, the filament spacing, the nature of the diffusion barrier and the Residual Resistivity Ratio (RRR) of the copper. The interstrand resistances for the cable are the key parameters for the losses. Thus, the nature of the strands coating or the presence of a stainless steel core can strongly diminish the cable losses. Finally, a design, for the strands and the cables for the fabrication of a quadrupole is proposed. (author)

Production of superconducting Nb3Sn wire using Nb or Nb(Ti) and Sn(Ga) solid solution powders

International Nuclear Information System (INIS)

Thieme, C.L.H.; Foner, S.

1991-01-01

This paper reports on superconducting Nb 3 Sn wire produced by the powder metallurgy method using Nb or Nb-2.9 at% Ti powder in combination with Sn-x at% Ga powders (x = 3, 4.2, 6.2 and 9.0). Ga additions to the Sn caused considerable solid solution hardening which improved its workability. It made the Nb-Sn(Ga) powder combinations convenient for swaging and extensive wire drawing. Anneals at 950 degrees C produced wires with an overall J c of 10 4 A/cm 2 at 21.9 T for wires with both Ti in the Nb and 6.2 at% Ga in the Sn. Comparison of this wire with the best Nb(Ti)-Cu-internal Sn(Ti) shows a higher J c per A15 areas, especially in fields of 22T and above

Microstructure and mechanical behavior of superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N biomedical alloys.

Science.gov (United States)

Ramarolahy, A; Castany, P; Prima, F; Laheurte, P; Péron, I; Gloriant, T

2012-05-01

In this study, the microstructure and the mechanical properties of two new biocompatible superelastic alloys, Ti-24Nb-0.5O and Ti-24Nb-0.5N (at.%), were investigated. Special attention was focused on the role of O and N addition on α(″) formation, supereleastic recovery and mechanical strength by comparison with the Ti-24Nb and Ti-26Nb (at.%) alloy compositions taken as references. Microstructures were characterized by optical microscopy, X-ray diffraction and transmission electron microscopy before and after deformation. The mechanical properties and the superelastic behavior were evaluated by conventional and cyclic tensile tests. High tensile strength, low Young's modulus, rather high superelastic recovery and excellent ductility were observed for both superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N alloys. Deformation twinning was shown to accommodate the plastic deformation in these alloys and only the {332} twinning system was observed to be activated by electron backscattered diffraction analyses. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mechanism of generation of large (Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel

Science.gov (United States)

Xie, You; Cheng, Guo-guang; Chen, Lie; Zhang, Yan-dong; Yan, Qing-zhong

2016-11-01

The characteristics and generation mechanism of (Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of (Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich (Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2-5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of (Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is (Ti0.511V0.356Nb0.133)(C x N y ), whereas that for the single Nb-rich phase is (Ti0.061V0.263Nb0.676)(C x N y ). The calculation results based on the Scheil-Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.

Effect of Nb-doped TiO{sub 2} on nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Saurdi, I., E-mail: saurdy788@gmail.com; Ishak, A. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); UiTM Sarawak Kampus Kota Samarahan Jalan Meranek, Sarawak (Malaysia); Shafura, A. K.; Azhar, N. E. A.; Mamat, M. H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); Malek, M. F.; Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), (Centre for Nano-Science and Nano-Technology), Institute of Science, Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, A. H. Salman; Khan, Haseeb A. [Department of Biochemistry, College of Science, Bldg. 5, King Saud University (KSU) P.O: 2455 Riyadh 1145 (Saudi Arabia)

2016-07-06

The Nb-doped TiO{sub 2} films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO{sub 2} films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO{sub 2} (TiO{sub 2}:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO{sub 2}:Nb-5at.%.

Dissolving of Nb and Ti carbonitride precipitates in microalloyed steels

Institute of Scientific and Technical Information of China (English)

Wenjin Nie; Shanwu Yang; Shaoqiang Yuan; Xinlai He

2003-01-01

The dissolving behaviour of Nb and Ti carbonitride precipitates in microalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electron microscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates in Nb-Ti microalloyed steel are (Nb, Ti)(C,N). With holding time increasing, the atomic ratio of Nb/Ti in precipitates decrease gradually. These precipitates still existe even after holding for 48 h at 1300℃ while Nb(C,N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the same temperature. These results show that formation and thermostability of precipitates are considerably influenced by interaction between Nb and Ti.

Thermomechanical processing of In-containing β-type Ti-Nb alloys.

Science.gov (United States)

Pilz, Stefan; Geissler, David; Calin, Mariana; Eckert, Jürgen; Zimmermann, Martina; Freudenberger, Jens; Gebert, Annett

2018-03-01

In this study, the effect of thermomechanical processing on microstructure evolution of the indium-containing β-type Ti alloys (Ti-40Nb)-3.5In and (Ti-36Nb)-3.5In was examined. Both alloys show an increased β-phase stability compared to binary alloys due to In additions. This leads to a reduced α''-phase fraction in the solution treated and recrystallized state in the case of (Ti-36Nb)-3.5In and to the suppression of stress-induced α'' formation and deformation twinning for (Ti-40Nb)-3.5In. The mechanical properties of the alloys were subsequently studied by quasistatic tensile tests in the recrystallized state, revealing reduced Young's modulus values of 58GPa ((Ti-40Nb)-3.5In) and 56GPa ((Ti-36Nb)-3.5In) compared to 60GPa as determined for Ti-40Nb. For both In-containing alloys the ultimate tensile strength is in the range of 560MPa. Due to the suppressed α'' formation, (Ti-40Nb)-3.5In exhibits a linear elastic deformation behavior during tensile loading together with a low Young's modulus and is therefore promising for load-bearing implants. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of nitrogen addition on superelasticity of Ti-Zr-Nb alloys

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Miyazaki, Shuichi; Inamura, Tomonari; Hosoda, Hideki

2008-01-01

Recently, the Ti-Zr-Nb alloys have been developed as Ni-free shape memory and superelastic alloys. In this study, the effect of Nb and nitrogen (N) contents on martensitic transformation behavior, shape memory effect and superelasticity in Ti-18Zr-(12-16)Nb-(0-1.0)N (at%) alloys were investigated using tensile tests, optical microscopy and X-ray diffraction. Shape memory effect was observed in Ti-18Zr-(12-13)Nb and Ti-18Zr-12Nb-0.5N alloys at room temperature. The superelastic behavior appeared by the increase of Nb or N content. The Ti-18Zr-(14-15)Nb, Ti-18Zr-(13-14)Nb-0.5N and Ti-18Zr-(12-14)Nb-1.0N alloys exhibited the superelasticity at room temperature. The martensitic transformation start temperature (M s ) decreased by 75 K with 1 at% increase of N content for Ti-18Zr-13Nb alloy. The critical stress for slip deformation and the stress for inducing the martensitic transformation increased with increasing N content. The superelastic recovery strain was also increased by adding N. The maximum recovery strain of 5.0% was obtained in the Ti-18Zr-14Nb-0.5N alloy. (author)

Structural stability of characteristic interface for NiTi/Nb Nanowire: First-Principle study

Science.gov (United States)

Li, G. F.; Zheng, H. Z.; Shu, X. Y.; Peng, P.

2016-01-01

Compared with some other conventional interface models, the interface of NiTi(211)/Nb(220) in NiTiNb metal nanocomposite had been simulated and analyzed carefully. Results show that only several interface models, i.e., NiTi(100)/Nb(100)(Ni⃡Nb), NiTi(110)/Nb(110) and NiTi(211)/Nb(220), can be formed accordingly with their negative formation enthalpy. Therein the cohesive energy Δ E and Griffith rupture work W of NiTi(211)/Nb(220) interface model are the lowest among them. Density of states shows that there exists only one electronic bonding peak for NiTi(211)/Nb(220) interface model at -2.5 eV. Electron density difference of NiTi(211)/ Nb(220) shows that the Nb-Nb, Nb-Ti and Nb-Ni bonding characters seem like so peaceful as a fabric twisting every atom, which is different from conventional metallic bonding performance. Such appearance can be deduced that the metallic bonding between Nb-Nb, Nb-Ti and Nb-Ni in NiTi(211)/Nb(220) may be affected by its nanostructure called nanometer size effect. Thus, our findings open an avenue for detailed and comprehensive studies of nanocomposite.

40 mm bore Nb-Ti model dipole magnet

International Nuclear Information System (INIS)

Taylor, C.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J.; Scanlan, R.

1984-01-01

Preliminary R and D has been started on magnets for a next-generation high-energy-physics accelerator, the 20 TeV Superconducting Supercollider (SSC). One design now being developed at LBL is described in this paper. The design is based on two layers of flattened Nb-Ti cable, a 40 mm ID winding with flared ends, and an operating field of 6.5 T. Experimental results are presented on several one-meter-long models tested at both He I and He II temperature. Measurement of field, residual magnetization, quench propagation velocity, and winding prestress are presented. (A 2-in-1 magnet based on this coil design is being jointly developed by LBL and Brookhaven National Laboratory, and 15 ft. long models are being constructed at BNL)

Development and manufacturing of a Nb$_{3}$Sn quadrupole magnet Model at CEA/Saclay for TESLA Interaction Region

CERN Document Server

Durante, Maria; Fratini, M; Leboeuf, D; Segreti, M; Védrine, Pierre; 10.1109/TASC.2004.829129

2004-01-01

One possible application of Nb/sub 3/Sn, whose superconducting properties far exceed those of NbTi, is the fabrication of short and powerful quadrupole magnets for the interaction regions of large particle accelerators. In some projects, as in the future linear collider TESLA, the quadrupole magnets are inside the detector solenoid and must operate in its background field. This situation gives singular Lorentz force distribution in the ends of the magnet. To learn about Nb/sub 3/Sn technology, evaluate fabrication techniques and test the interaction with a solenoidal field, DAPNIA /SACM at CEA/Saclay has started the manufacturing of a 1-m-long, 56- mm-single-aperture quadrupole magnet model. The model relies on the same coil geometry as the LHC arc quadrupole magnets, but has no iron yoke. It will produce a nominal field gradient of 211 T/m at 11,870 A. The coils are wound from Rutherford-type cables insulated with glass fiber tape, before being heat-treated and vacuum-impregnated with epoxy resin. Laminated,...

Solubilization and precipitation of {omega} and {alpha} phases in Ti-30 Nb and Ti-35 Nb alloys; Solubilizacao e precipitacao de fases {omega} e {alpha} nas ligas Ti-30Nb e Ti-35Nb

Energy Technology Data Exchange (ETDEWEB)

Hayama, A.O.F.; Lopes, J.F.S.C.; Caram, R., E-mail: alexandrah@fem.unicamp.b [Universidade Estadual de Campinas (DEMa/FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Engenharia de Materiais

2010-07-01

This work presents the main results of the characterization of Ti-30Nb and Ti-35Nb alloys (wt%) submitted to the solutioning heat treatment following by aging. Samples were obtained by electric arc melting, followed by solution heat treatment at 1000 deg C during 8 hours and cooling in water, the microstructure obtained is formed by {beta} and {alpha} phases. Samples were aged at 260 and 400 deg C during periods of time varying from 1 to 240 min. Characterization was performed using light optical microscopy, X-ray diffraction, Young's modulus measurements by acoustic emission and Vickers hardness. The results show the presence of {beta} and {alpha}{sup '}' phases in samples of the Ti-30Nb alloy aged at 260 deg C. In samples aged at 400 deg C, precipitation of {omega} and {alpha}{sup '}' phases took place, and due to this fact, an increase in Young's modulus and in hardness occurred. (author)

AC loss time constant measurements on Nb3Al and NbTi multifilamentary superconductors

International Nuclear Information System (INIS)

Painter, T.A.

1988-03-01

The AC loss time constant is a previously univestigated property of Nb 3 Al, a superconductor which, with recent technological developments, shows some advantages over the more commonly used superconductors, NbTi and Nb 3 Sn. Four Nb 3 Al samples with varying twist pitches and one NbTi sample are inductively measured for their AC loss time constants. The measured time constants are compared to the theoretical time constant limits imposed by the limits of the transverse resistivity found by Carr [5] and to the theoretical time constants found using the Bean Model as well as to each other. The measured time constants of the Nb 3 Al samples fall approximately halfway between the theoretical time constant limits, and the measured time constants of the NbTi sample is close to the theoretical lower time constant limit. The Bean Model adequately accounts for the variance of the permeability of the Nb 3 Al superconductor in a background magnetic field. Finally, the measured time constant values of the Nb 3 Al samples vary approximately according to the square of their twist pitch. (author)

Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

Science.gov (United States)

Li, Kun; Li, Yan; Huang, Xu; Gibson, Des; Zheng, Yang; Liu, Jiao; Sun, Lu; Fu, Yong Qing

2017-08-01

Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb2O5. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (Ecorr) and lower corrosion current densities (icorr) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of Ecorr and icorr was found among the Ni-Ti-Nb films.

Surface microstructures and corrosion resistance of Ni-Ti-Nb shape memory thin films

Energy Technology Data Exchange (ETDEWEB)

Li, Kun [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Huang, Xu [Memry Corporation, Bethel, CT 06801 (United States); Gibson, Des [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Zheng, Yang; Liu, Jiao; Sun, Lu [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, Beijing 100191 (China); Fu, Yong Qing, E-mail: richard.fu@northumbria.ac.uk [Faculty of Engineering and Environment, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom)

2017-08-31

Highlights: • The corrosion resistance of Ni-Ti-Nb shape memory thin films is investigated. • Modified surface oxide layers improve the corrosion resistance of Ni-Ti-Nb films. • Further Nb additions reduce the potential corrosion tendency of the films. - Abstract: Ni-Ti-Nb and Ni-Ti shape memory thin films were sputter-deposited onto silicon substrates and annealed at 600 °C for crystallization. X-ray diffraction (XRD) measurements indicated that all of the annealed Ni-Ti-Nb films were composed of crystalline Ni-Ti (Nb) and Nb-rich grains. X-ray photoelectron spectroscopy (XPS) tests showed that the surfaces of Ni-Ti-Nb films were covered with Ti oxides, NiO and Nb{sub 2}O{sub 5}. The corrosion resistance of the Ni-Ti-Nb films in 3.5 wt.% NaCl solution was investigated using electrochemical tests such as open-circuit potential (OCP) and potentio-dynamic polarization tests. Ni-Ti-Nb films showed higher OCPs, higher corrosion potentials (E{sub corr}) and lower corrosion current densities (i{sub corr}) than the binary Ni-Ti film, which indicated a better corrosion resistance. The reason may be that Nb additions modified the passive layer on the film surface. The OCPs of Ni-Ti-Nb films increased with further Nb additions, whereas no apparent difference of E{sub corr} and i{sub corr} was found among the Ni-Ti-Nb films.

Ceramic insulation for superconducting Nb{sub 3}Sn cables; Isolation ceramique pour cables supraconducteurs en Nb{sub 3}Sn

Energy Technology Data Exchange (ETDEWEB)

Puigsegur, A

2005-01-15

Nb{sub 3}Sn is the best superconductor candidate for the realization of high field magnets (>11 Tesla), its implementation remains delicate because of the great brittleness of material after the heat treatment necessary to the formation of Nb{sub 3}Sn compounds. The conventional insulation for Nb{sub 3}Sn requires to perform, after the heat treatment, a vacuum resin impregnation, which adds to the cost and raises failure risk. We have proposed an innovating ceramic insulation deposited directly on the unreacted conducting cable. After the heat treatment of the niobium tin, we obtain a coil having a mechanical cohesion, while maintaining a proper conductor positioning and a suitable electric insulation. After a rheological study, to characterize the impregnated suspension, we have shown that using this insulation in a coil manufacture process does not affect the electrical properties of the Nb{sub 3}Sn wires. A solenoid of small dimensions was tested with success in high external magnetic fields and has produced a magnetic field of 3.8 T under 740 A. (author)

Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

Science.gov (United States)

Zarrin, Saviz; Heshmatpour, Felora

2018-06-05

In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

Study of Nb3Sn cables for superconducting quadrupoles

International Nuclear Information System (INIS)

Otmani, R.

1999-10-01

In particle physics, the quest for higher energies may be satisfied by the use of niobium-tin superconducting magnets. Such magnets are made of Rutherford type cables which are wound from superconducting strands. The strands are made by the 'internal tin' method. The aim of this study is to determine the main parameters for the fabrication of a quadrupole. The two main requirements the cable must fulfill are high critical current and low losses. The main parameters were determined from different measurements and models. Thus, the key parameters for the current transport capacity are the number and the diameter of the filaments, the number of sub-elements, the surface of superconductor and the copper-to-non-copper ratio. For the hysteresis losses, the main parameters appear to be the effective filament diameter and the spacing of the filaments. For intra-strand losses, the main parameters appear to be the filaments' diameter, the filament spacing, the nature of the diffusion barrier and the Residual Resistivity Ratio (RRR) of the copper. The interstrand resistances for the cable are the key parameters for the losses. Thus, the nature of the strands coating or the presence of a stainless steel core can strongly diminish the cable losses. Finally, a design, for the strands and the cables for the fabrication of a quadrupole is proposed. (author)

A nano lamella NbTi–NiTi composite with high strength

Energy Technology Data Exchange (ETDEWEB)

Jiang, Jiang [Jiangxi Key Laboratory of Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Institute of Applied Physics of Jiangxi Academy of Sciences, Nanchang 330029 (China); State Key Laboratory of Heavy Oil Processing and Department of Materials Science and engineering, China University of Petroleum, Beijing 102249 (China); Jiang, Daqiang [State Key Laboratory of Heavy Oil Processing and Department of Materials Science and engineering, China University of Petroleum, Beijing 102249 (China); School of Mechanical and Chemical Engineering, The University of Western Australia, WA 6009 (Australia); Hao, Shijie; Yu, Cun; Zhang, Junsong [State Key Laboratory of Heavy Oil Processing and Department of Materials Science and engineering, China University of Petroleum, Beijing 102249 (China); Ren, Yang [X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Lu, Deping; Xie, Shifang [Jiangxi Key Laboratory of Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Institute of Applied Physics of Jiangxi Academy of Sciences, Nanchang 330029 (China); Cui, Lishan, E-mail: lishancui63@126.com [State Key Laboratory of Heavy Oil Processing and Department of Materials Science and engineering, China University of Petroleum, Beijing 102249 (China)

2015-05-01

A hypereutectic Nb{sub 60}Ti{sub 24}Ni{sub 16} (at%) alloy was prepared by vacuum induction melting, and a nano lamellae NbTi–NiTi composite was obtained by hot-forging and wire-drawing of the ingot. Microscopic analysis showed that NbTi and NiTi nano lamellae distributed alternatively in the composite, and aligned along the wire axial direction, with a high volume fraction (~70%) of NbTi nano lamellae. In situ synchrotron X-ray diffraction analysis revealed that stress induced martensitic transformation occurred upon loading, which would effectively weaken the stress concentration at the interface and avoid the introduction of defects into the nano reinforced phase. Then the embedded NbTi nano lamellae exhibited a high elastic strain up to 2.72%, 1.5 times as high as that of the Nb nanowires embedded in a conventional plastic matrix, and the corresponding stress carried by NbTi was evaluated as 2.53 GPa. The high volume fraction of NbTi nano lamellae improved the translation of high strength from the nano reinforced phase into bulk properties of the composite, with a platform stress of ~1.7 GPa and a fracture strength of ~1.9 GPa.

Characterization and multi-scales modeling of the thermomechanical behaviour of a superconducting composite cable

International Nuclear Information System (INIS)

Gourdin, C.; Reytier, M.; Vedrine, P.

2000-06-01

The prediction of the superconducting cable mechanical properties (NbTi and Nb 3 Sn) becomes a great stake for the STCM applications. During the design phase of our magnets, the electromagnetic forces become considerable. Therefore, the control and the accuracy of the structural calculations need well known mechanical properties for each component. But, superconducting cables present, in compression, a non linear mechanical behaviour with a significant hysteresis, which will have to be taken into account in a near future. That is why a study is started in order to understand and to formulate this particular mechanical behaviour. In this paper, the NbTi and Nb 3 Sn cable structure is first presented as well as their manufacturing process. Then, a description of the experimental procedure used to realize the compression tests is made. Finally, the main results obtained at room temperature and also in liquid helium at 4.2 K are discussed. (author)

ADHESION OF BIOCOMPATIBLE TiNb COATING

Directory of Open Access Journals (Sweden)

Tomas Kolegar

2017-06-01

Full Text Available Preparation of a coating with a high quality requires good adhesion of the film to the substrate. The paper deals with the adhesion of biocompatible TiNb coating with different base materials. Several materials such as titanium CP grade 2, titanium alloys Ti6Al4V and stainless steel AISI 316L were measured. Testing samples were made in the shape of small discs. Those samples were coated with a TiNb layer by using the PVD method (magnetron sputtering. Onto the measured layer of TiNb an assistant cylinder was stuck using a high strength epoxy adhesive E1100S. The sample with the assistant cylinder was fixed into a special fixture and the whole assembly underwent pull-off testing for adhesion. The main result of this experiment was determining the strength needed to peel the layer and morphology and size of the breakaway. As a result, we will be able to determine the best base material and conditions where the coating will be remain intact with the base material.

Carbide precipitation kinetics in austenite of a Nb-Ti-V microalloyed steel

International Nuclear Information System (INIS)

Jung, Jae-Gil; Park, June-Soo; Kim, Jiyoung; Lee, Young-Kook

2011-01-01

Highlights: → Carbide precipitation kinetic was fastest at 950 deg. C and accelerated by strain. → Nucleation sites for (Nb,Ti)C above 950 deg. C were mainly undissolved (Ti,Nb)(C,N). → Strain enabled (Nb,Ti)C to nucleate on all sides of (Ti,Nb)(C,N) above 950 deg. C. → Strain changed nucleation sites from (Ti,Nb)(C,N) to dislocations below 900 deg. C. → Strain also accelerated the change in particle composition to equilibrium one. - Abstract: The isothermal precipitation kinetics of carbides in both strain-free and strained austenite (γ) of a microalloyed steel were quantitatively investigated through the electrical resistivity and transmission electron microscopy. The (Nb,Ti)C carbides at the interfaces of the undissolved (Ti,Nb)(C,N) carbonitrides were observed at all temperatures in strain-free γ. However, for strain-induced precipitation, above 950 deg. C, the precipitation of (Nb,Ti)C carbides near the undissolved (Ti,Nb)(C,N) carbonitrides was predominant due to the recrystallization of strained γ. Meanwhile, the fine (Nb,Ti,V)C carbides were homogeneously precipitated in non-recrystallized γ at 850 deg. C and 900 deg. C, as well as near the undissolved (Ti,Nb)(C,N) particles. The electrical resistivity method was successfully used to quantitatively measure the isothermal precipitation kinetics of carbides in both strain-free and strained γ. The precipitation-time-temperature diagrams of the carbide in strain-free and strained γ, with nose temperatures of 950 deg. C, were generated and the precipitation kinetics were greatly accelerated by the applied strain.

Transverse Load Optimisation in Nb3Sn CICC Design; Influence of Cabling, Void Fraction and Strand Stiffness

NARCIS (Netherlands)

Nijhuis, Arend; Ilyin, Y.

2006-01-01

We have developed a model that describes the transverse load degradation in Nb3Sn CICCs, based on strand and cable properties, and that is capable of predicting how such degradation can be prevented. The Nb3Sn cable in conduit conductors (CICCs) for the International Thermonuclear Experimental

Upper critical fields in multifilamentary NbTi alloy superconducting wires

International Nuclear Information System (INIS)

Watanabe, Kazuo; Muto, Yoshio; Noto, Koshichi.

1991-01-01

In order to improve the high field performance of superconducting magnets, the upper critical field B c2 for practical multifilamentary alloy wires of NbTi, NbTiTa and NbTiHf were examined in respect with the usage of a pressurized superfluid cooling technique. The addition of Ta or Hf to NbTi enhanced by 0.5 T for B c2 at 1.8 K. Although the addition of a heavy element such as Ta or Hf has been regarded as suppressing Pauli-paramagnetism so far, it was found that the mechanism for B c2 enhancement by Hf addition is different from that by Ta addition. (author)

Microstructural and mechanical characterization of biomedical Ti-Nb-Zr(-Ta) alloys

International Nuclear Information System (INIS)

Elias, L.M.; Schneider, S.G.; Schneider, S.; Silva, H.M.; Malvisi, F.

2006-01-01

In recent years there has been a significant development of novel implant alloys based on β-Ti such as Ti-Nb-Zr and Ti-Nb-Zr-Ta alloys systems. The purpose of this work is to provide characterization of Ti-35.3Nb-5.1Ta-7.1Zr and Ti-41.1Nb-7.1Zr alloys, in which Nb will substitute the atomic amount of Ta, with emphasis in the property-microstructure-composition relationships. These alloys are produced from commercially pure materials (Ti, Nb, Zr and Ta) by an arc melting method. All ingots were submitted to sequences of heat treatment (1000 deg. C/2 h - WQ), cold working by swaging procedures and other heat treatment (1000 deg. C/2 h - WQ). Specimens, in as cast and heat-treated condition, were examined by light and scanning electron microscopy (SEM). These results suggested the presence of β- and ω-phases. Mechanical properties were based on tensile and hardness tests. These alloys exhibit a lower modulus than that of conventional Ti alloys and the other mechanical properties are suitable for biomedical applications

Alternating magnetic field losses in ATLAS type aluminium stabilized NbTi superconductors

CERN Document Server

Boxman, E W; ten Kate, H H J

2002-01-01

During ramping up- and down of the current in large-scale magnets the ramp losses are an important factor affecting the thermal and electro-magnetic stability of the system. The calculation of the losses is not straightforward due to the large dimensions of the conductor (~600 mm/sup 2/) implying that diffusion effects have to be taken into account. The AC-losses of the Al stabilized NbTi cable conductors used in the ATLAS magnet system were measured in 0.5 m long samples, using an inductive method with pick-up coils as well as the calorimetric method. External varying magnetic fields up to 2 tesla amplitude were applied parallel and perpendicular to the conductor wide surface. The results are compared to theory. It is found that hysteresis loss, eddy current loss in the Aluminum cladding and cable-to-cladding coupling loss contribute most to the AC loss. (5 refs).

Solubilization and precipitation of ω and α phases in Ti-30 Nb and Ti-35 Nb alloys

International Nuclear Information System (INIS)

Hayama, A.O.F.; Lopes, J.F.S.C.; Caram, R.

2010-01-01

This work presents the main results of the characterization of Ti-30Nb and Ti-35Nb alloys (wt%) submitted to the solutioning heat treatment following by aging. Samples were obtained by electric arc melting, followed by solution heat treatment at 1000 deg C during 8 hours and cooling in water, the microstructure obtained is formed by β and α phases. Samples were aged at 260 and 400 deg C during periods of time varying from 1 to 240 min. Characterization was performed using light optical microscopy, X-ray diffraction, Young's modulus measurements by acoustic emission and Vickers hardness. The results show the presence of β and α ' ' phases in samples of the Ti-30Nb alloy aged at 260 deg C. In samples aged at 400 deg C, precipitation of ω and α ' ' phases took place, and due to this fact, an increase in Young's modulus and in hardness occurred. (author)

Topotactic dehydration of the lamellar oxide HK2Ti5NbO14 x H2O: the oxide K4Ti10Nb2O27

International Nuclear Information System (INIS)

Grandin, A.; Borel, M.M.; Hervieu, M.; Raveau, B.

1987-01-01

The lamellar oxide HK 2 Ti 5 NbO 14 x H 2 O can be topotactically dehydrated to K 4 Ti 10 Nb 2 O 27 . Electron diffraction and X-ray diffraction studies of this phase lead to a monoclinic cell with the parameters a = 17.005, b = 3.78, c = 9.01 A and β 92.14 0 . Diffusion streaks on the electron diffraction patterns indicate disorder whereas the existence of two sets of lattices on the same crystal give evidence of the topotactic character of the reaction. A structural model is proposed for K 4 Ti 10 Nb 2 O 27 , which corresponds to the intergrowth of K 3 TiNbO 14 layers with the K 2 Ti 6 O 13 tunnel structure. The possibility of formation of various intergrowths such as (KTi 5 NbO 13 )/sub n/ (HK 2 Ti 5 NbO 14 )/sub n/' is suggested

Technology development of fabrication NbTi and Nb3 Sn superconducting wires

International Nuclear Information System (INIS)

Rodrigues Junior, D.; Bormio, C.; Baldan, C.A.; Ramos, M.J.; Pinatti, D.G.

1988-01-01

The technology development of NbTi and Nb 3 Sn superconducting wires are studied, mentioning the use of fluxes capture theory in the sizing of wires fabrication. The fabrication process, the thermal treatment and the experimental datas of critical temperature and current of Nb 3 Sn wires are described. (C.G.C.) [pt

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

KAUST Repository

Ozdogan, K.

2012-03-08

We study epitaxial SrTiO3 interfaced with Nb-doped SrTi1-x Nb x O3 (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We obtain a monotonous increase of the carrier density with the Nb concentration. The results are confirmed by experiments for SrTi0.88Nb0.12O3 and SrTi0.8Nb0.2O3, demonstrating the predictive power and limitations of our theoretical approach. We also show that the Seebeck coefficient decreases monotonously with increasing temperature.

Enhanced carrier density in Nb-doped SrTiO3 thermoelectrics

KAUST Repository

Ozdogan, K.; Upadhyay Kahaly, M.; Sarath Kumar, S. R.; Alshareef, Husam N.; Schwingenschlö gl, Udo

2012-01-01

We study epitaxial SrTiO3 interfaced with Nb-doped SrTi1-x Nb x O3 (x = 0, 0.125, 0.25, 0.375, and 0.5) by full-potential density functional theory. From the electronic band structures obtained by our ab-initio calculations we determine the dependence of the induced metallicity on the Nb concentration. We obtain a monotonous increase of the carrier density with the Nb concentration. The results are confirmed by experiments for SrTi0.88Nb0.12O3 and SrTi0.8Nb0.2O3, demonstrating the predictive power and limitations of our theoretical approach. We also show that the Seebeck coefficient decreases monotonously with increasing temperature.

Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

International Nuclear Information System (INIS)

Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching; Lee, Chih-Jhan; Ho, Wen-Fu

2010-01-01

In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable β phase began. However, when 4 mass% Fe or greater was added, the β phase was entirely retained with a bcc crystal structure. Moreover, the ω phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of ω phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9 o ) and Ti-5Nb-5Fe (29.5 o ) alloys were greater than that of c.p. Ti (2.7 o ) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

Energy Technology Data Exchange (ETDEWEB)

Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching [Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung 40605, Taiwan (China); Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Changhua 51591, Taiwan (China); Lee, Chih-Jhan [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Ho, Wen-Fu, E-mail: fujii@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China)

2010-09-15

In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable {beta} phase began. However, when 4 mass% Fe or greater was added, the {beta} phase was entirely retained with a bcc crystal structure. Moreover, the {omega} phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of {omega} phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9{sup o}) and Ti-5Nb-5Fe (29.5{sup o}) alloys were greater than that of c.p. Ti (2.7{sup o}) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

A success story LHC cable production at ALSTOM-MSA

CERN Document Server

Mocaer, P; Köhler, C; Verwaerde, C

2005-01-01

ITER, when constructed, will be the equipment using the largest amount of superconductor strands ever built (Nb$_{3}$Sn and NbTi). ALSTOM- MSA Magnets and Superconductors SA, "ALSTOM-MSA" received in 1998 the largest orders to date for the delivery of superconducting strands and cables (3100 km of cables for dipole and quadrupole magnets and various strands) for the Large Hadron Collider (LHC) being built at CERN Geneva. These orders to ALSTOM-MSA correspond to more than 600 metric tons of superconducting strands, an amount to be compared to around 600 metric tons of Nb$_{3}$Sn strands and 250 metric tons of NbTi strands necessary for ITER. Starting from small and short R&D programs in the early nineties, ALSTOM-MSA has reached its industrial targets and has, as of September 2004, delivered around 74% of the whole orders with products meeting high quality standards. Production is going on at contractual delivery rate and with satisfactory financial results to finish deliveries around end 2005, taking into...

High temperature oxidation of β-NbTi alloys

International Nuclear Information System (INIS)

Parida, S.C.; Gupta, N.K.; Rama Rao, G.A.; Sen, B.K.; Krishnan, K.

2008-01-01

The isothermal oxidation kinetics of pure Ti metal and two different β-NbTi alloys with compositions of 85 and 75 at.% Ti were studied using thermogravimetric technique in the temperature range of 1073-1323 K at an interval of 50 K. The value of the power exponent n of the rate equation was found to be close to one suggesting that each reaction follows first order kinetic rate law. X-ray diffraction analysis of oxidation products at each temperature revealed the simultaneous formation of TiO 2 and TiNb 2 O 7 . The rate constants and the activation energies of oxidation reactions for each alloy compositions were evaluated. (author)

Electrochemical and surface behavior of hydyroxyapatite/Ti film on nanotubular Ti-35Nb-xZr alloys

International Nuclear Information System (INIS)

Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A.

2012-01-01

In this paper, we investigated the electrochemical and surface behavior of hydroxyapatite (HA)/Ti films on the nanotubular Ti-35Nb-xZr alloy. The Ti-35Nb-xZr ternary alloys with 3-10 wt.% Zr content were made by an arc melting method. The nanotubular oxide layers were developed on the Ti-35Nb-xZr alloys by an anodic oxidation method in 1 M H 3 PO 4 electrolyte containing 0.8 wt% NaF at room temperature. The HA/Ti composite films on the nanotubular oxide surfaces were deposited by a magnetron sputtering method. Their surface characteristics were analyzed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and an X-ray diffractometer (XRD). The corrosion behavior of the specimens was examined through potentiodynamic and AC impedance tests in 0.9% NaCl solution. From the results, the Ti-35Nb-xZr alloys showed a solely β phase microstructure that resulted from the addition of Zr. The nanotubular structure formed with a diameter of about 200 nm, and the HA/Ti thin film was deposited on the nanotubular structure. The HA/Ti thin film-coated nanotubular Ti-35Nb-xZr alloys showed good corrosion resistance in 0.9% NaCl solution.

Structural evolution of Ba8Ti3Nb4O24 from BaTiO3 using a series of Ba(Ti1−5xNb4x)O3 solid solutions

International Nuclear Information System (INIS)

Barrientos Hernández, F.R.; Lira Hernández, I.A.; Gómez Yáñez, C.; Arenas Flores, A.; Cabrera Sierra, R.; Pérez Labra, M.

2014-01-01

Highlights: • The evolution phase Ba 8 Ti 3 Nb 4 O 24 was obtained through the mechanism Ba(Ti 1-5x Nb 4x )O 3 . • Addition of niobium can accelerate grain growth of BaTiO 3 ceramics. • Ba 8 Ti 3 Nb 4 O 24 presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb 5+ content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba 8 Ti 3 Nb 4 O 24 by adding Nb 2 O 5 to perovskite structure of BaTiO 3 was investigated. The compositions Ba(Ti 1-5x Nb 4x )O 3 ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO 3 , BaCO 3 and Nb 2 O 5 , were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba 8 Ti 3 Nb 4 O 24 from BaTiO 3 was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba 8 Ti 3 Nb 4 O 24 which resonates at microwave frequencies

High-field superconductivity in the Nb-Ti-Zr ternary system

International Nuclear Information System (INIS)

Ralls, K.M.; Rose, R.M.; Wulff, J.

1980-01-01

Resistive critical current densities, critical fields, and normal-state electrical resistivities were obtained at 4.2 0 K for 55 alloys in the Nb-Ti-Zr ternary alloy system, excepting Ti-Zr binary compositions. The resistive critical field as a function of ternary composition has a saddle point between the Nb-Ti and Nb-Zr binaries, so that ternary alloying in this system is not expected to result in higher critical fields than the binary alloys

High-field superconductivity in the Nb-Ti-Zr ternary system

Science.gov (United States)

Ralls, K. M.; Rose, R. M.; Wulff, J.

1980-06-01

Resistive critical current densities, critical fields, and normal-state electrical resistivities were obtained at 4.2 °K for 55 alloys in the Nb-Ti-Zr ternary alloy system, excepting Ti-Zr binary compositions. The resistive critical field as a function of ternary composition has a saddle point between the Nb-Ti and Nb-Zr binaries, so that ternary alloying in this system is not expected to result in higher critical fields than the binary alloys.

Electrochemical characterization and redox behavior of Nb-doped SrTiO3

DEFF Research Database (Denmark)

Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L. Reine

2009-01-01

Sr-vacancy compensated Nb-doped SrTiO3 with the nominal composition Sr0.94Ti0.9Nb0.1O3 has been evaluated as a solid oxide fuel cell (SOFC) anode material in terms of redox stability and electrochemical properties. Sr0.94Ti0.9Nb0.1O3 has been synthesized with a recently developed modified glycine......-nitrate process. The phase purity and redox behavior have been analyzed with XRD and TGA. The electrochemical properties of Sr0.94Ti0.9Nb0.1O3 and a composite electrode of Sr0.94Ti0.9Nb0.1O3/YSZ have been investigated by electrochemical impedance spectroscopy (EIS) on cone shaped electrodes and on electrodes...... in a symmetrical cell configuration. The experiments indicated that the Nb-doped SrTiO3 electrodes were redox stable and showed a potential ability to be used as a part of a SOFC anode. The electrochemical activity appeared to be governed by the concentration of defect species (especially Ti3+ and V-0...

On the hardenability of Nb-modified metastable beta Ti-5553 alloy

Energy Technology Data Exchange (ETDEWEB)

Campo, K.N.; Andrade, D.R.; Opini, V.C.; Mello, M.G.; Lopes, E.S.N.; Caram, R., E-mail: caram@fem.unicamp.br

2016-05-15

Among the commercially available titanium alloys, the metastable β Ti-5553 alloy (Ti–5Al–5V–5Mo–3Cr–0.5Fe wt.%) is an object of great interest because it is employed in aerospace structural applications, primarily in the replacement of steel components. One of the primary advantages of this alloy is its high hardenability, which allows it to retain the β phase at room temperature, even at low cooling rates, thereby allowing the thermoprocessing of thick parts. The aim of this investigation was to evaluate the effect of the replacement of V with Nb on the hardenability of Ti-5553. Based on the molybdenum equivalent criterion, the Nb-modified Ti-5553 alloy was designed to present 12 wt.% of Nb instead of 5 wt.% of V. Samples of both alloys were prepared by melting them in an arc furnace under an inert atmosphere, heat-treated at high temperatures for 12 h and plastic deformed using swage forging. Finally, these samples were solution heat-treated at temperatures above the β-transus followed by cooling at different rates using water quenching, furnace cooling and a modified Jominy end quench test. Characterization was performed by measuring Vickers hardness, X-ray diffraction, and light optical, scanning electron and transmission electron microscopy. The results obtained indicate that metastable β phase can be retained when the cooling rate is higher than 21 °C/s for both alloys. At lower cooling rates, α phase precipitation was observed, but it appeared to be less evident in the Nb-modified Ti-5553, suggesting that the replacement of V with Nb increased the hardenability of the alloy. - Highlights: • Hardenability of Ti alloys are assessed using a modified Jominy end quench test. • Ti-5553 and Nb-modified Ti-5553 are subjected to continuous cooling experiments. • β phase decomposition kinetics is reduced by replacing V with Nb in Ti-5553. • Nb-modified Ti-5553 features improved hardenability. • Replacement of V with Nb causes the �

Analysis of ITER NbTi and Nb3Sn CICCs experimental minimum quench energy with JackPot, MCM and THEA models

Science.gov (United States)

Bagni, T.; Duchateau, J. L.; Breschi, M.; Devred, A.; Nijhuis, A.

2017-09-01

Cable-in-conduit conductors (CICCs) for ITER magnets are subjected to fast changing magnetic fields during the plasma-operating scenario. In order to anticipate the limitations of conductors under the foreseen operating conditions, it is essential to have a better understanding of the stability margin of magnets. In the last decade ITER has launched a campaign for characterization of several types of NbTi and Nb3Sn CICCs comprising quench tests with a singular sine wave fast magnetic field pulse and relatively small amplitude. The stability tests, performed in the SULTAN facility, were reproduced and analyzed using two codes: JackPot-AC/DC, an electromagnetic-thermal numerical model for CICCs, developed at the University of Twente (van Lanen and Nijhuis 2010 Cryogenics 50 139-148) and multi-constant-model (MCM) (Turck and Zani 2010 Cryogenics 50 443-9), an analytical model for CICCs coupling losses. The outputs of both codes were combined with thermal, hydraulic and electric analysis of superconducting cables to predict the minimum quench energy (MQE) (Bottura et al 2000 Cryogenics 40 617-26). The experimental AC loss results were used to calibrate the JackPot and MCM models and to reproduce the energy deposited in the cable during an MQE test. The agreement between experiments and models confirm a good comprehension of the various CICCs thermal and electromagnetic phenomena. The differences between the analytical MCM and numerical JackPot approaches are discussed. The results provide a good basis for further investigation of CICC stability under plasma scenario conditions using magnetic field pulses with lower ramp rate and higher amplitude.

Development of superconducting wire and cable for the SSC project in Sumitomo Electric Industries

International Nuclear Information System (INIS)

Sashida, T.; Saito, S.; Oku, G.; Kurimoto, K.; Yamada, Y.; Yokota, M.; Ohmatsu, K.; Nagata, M.

1991-01-01

As a large production volume of NbTi superconducting wire and cable is required for the SSC project, a production process has been developed at Sumitomo Electric to optimize critical variables of wire properties. To achieve high electrical properties and a high overall yield of NbTi alloy in the fabrication process, the authors have employed carefully designed large size multifilament billets weighing more than 350kg to decrease the number of billets in large production scale. The collider dipole magnet consists of inner and outer cables, and the cable should be as uniform as possible to ensure the performance of the magnets. The authors studied two aspects to obtain such uniformity of superconducting wire; one is the selection of unit weight and the other is the property of critical current density of a strand

A Nb3Sn high field dipole

International Nuclear Information System (INIS)

McClusky, R.; Robins, K.E.; Sampson, W.B.

1990-01-01

A dipole magnet approximately 1 meter long with an 8 cm bore has been fabricated from cable made from Nb 3 Sn multifilamentary strands. The coil consists of four layers of conductor wound in pairs to eliminate internal joints. Each set of layers is separately constrained with Kevlar-epoxy bands and the complete assembly clamped in a split laminated iron yoke. The inner coil pairs were wound before heat treating while the outer coils were formed from pre-reacted cable using conventional insulation. A NbTi version of the magnet was fabricated using SSC version of the magnet was fabricated using SSC conductor to test the construction techniques. This magnet reached a maximum central field of 7.6 Tesla, at 4.4K which is very close to the limit estimated from conductor measurements. The Nb 3 Sn magnet, however, only reached a maximum field at 8.1T considerably short of the field expected from measurements on the inner cable. 7 refs., 5 figs

Development of Nb3Sn AC superconducting wire. Pt. 2

International Nuclear Information System (INIS)

Kasahara, Hobun; Torii, Shinji; Akita, Shirabe; Ueda, Kiyotaka; Kubota, Yoji; Yasohama, Kazuhiko; Kobayashi, Hisayasu; Ogasawara, Takeshi.

1993-01-01

For the realization of superconducting power apparatus, it is important that the development of highly stable superconducting cables. Nb 3 Sn wire has higher critical temperature than NbTi wire. Therefore, it is possible to make highly stable superconducting wires. In this report, we examine a manufacturing process of Ac Nb 3 Sn wire. This manufacturing process has four times higher critical current density than conventional processes. We have made a 400 kVA class AC coil with React and Wind method. The loss density of this coil was 20MW/m 3 at just before the quench. In this case, the temperature of cable increased about 3.8 K. This means that the Nb 3 Sn coil has a very high stability. (author)

Stability in a long length NbTi CICC

CERN Document Server

Bottura, L; Gislon, P; Spadoni, M; Bellucci, P; Muzzi, L; Turtu, S; Catitti, A; Chiarelli, S; Della Corte, A; Di Ferdinando, E

2001-01-01

A crucial issue for a superconducting coil in order to be safely used in the magnetic system of a fusion reactor is stability against all foreseen disturbances. To simulate the fusion machine conditions, including off-normal events, e.g. plasma disruptions, the energy deposition has to be spread over a "long length" cable in conduit conductor (CICC) and a background magnetic field is needed. We have therefore designed and built an experiment consisting of an instrumented NbTi test module inserted in a pair of co-axial pulsed copper coils. A 0.6 m diameter superconducting coil provides a background magnetic field up to 3 T. Calibration of the energy inductively coupled between the pulsed coils and the module has been obtained measuring the system temperature increase just after the pulse by means of thermometers positioned along the conductor. Stability vs. operating current I/sub op/ has been examined for different helium temperatures and different background magnetic fields. The finite element code Gandalf f...

High-temperature fracture and fatigue resistance of a ductile β-TiNb reinforced γ-TiAl intermetallic composite

International Nuclear Information System (INIS)

Rao, K.T.V.; Ritchie, R.O.

1998-01-01

The high-temperature fatigue-crack propagation and fracture resistance of a model γ-TiAl intermetallic composite reinforced with 20 vol. % ductile β-TiNb particles is examined at elevated temperatures of 650 and 800 C and compared with behavior at room temperature. TiNb reinforcements are found to enhance the fracture toughness of γ-TiAl, even at high temperatures, from about 123 to ∼40 MPa m 1/2 , although their effectiveness is lower compared to room temperature due to the reduction in strength of TiNb particles. Under monotonic loading, crack-growth response in the composite is characterized by resistance-curve behavior arising from crack trapping, renucleation and resultant crack bridging effects attributable to the presence of TiNb particles. In addition, crack-tip blunting associated with plasticity increases the crack-initiation (matrix) toughness of the composite, particularly at 800 C, above the ductile-to-brittle transition temperature (DBTT) for γ-TiAl. High-temperature fatigue-crack growth resistance, however, is marginally degraded by the addition of TiNb particles in the C-R (edge) orientation, similar to observations made at room temperature; premature fatigue failure of TiNb ligaments in the crack wake diminishes the role of bridging under cyclic loading. Both fatigue and fracture resistance of the composite are slightly lower at 650 C (just below the DBTT for TiAl) compared to the behavior at ambient and 800 C. Overall, the beneficial effect of adding ductile TiNb reinforcements to enhance the room-temperature fracture and fatigue resistance of γ-TiAl alloys is retained up to 800 C, in air environments. There is concern, however, regarding the long-term environmental stability of these composite microstructures in unprotected atmospheres

Once upon a time, there was a brittle but superconducting niobium-tin…

CERN Multimedia

Stefania Pandolfi

2016-01-01

The production of the new niobium-tin cables for the high-performance superconducting magnets of the HL-LHC is now in full swing at CERN.   The Rutherford cabling machine is operating in the superconducting laboratory, in Building 163. (Photo: Max Brice/CERN) Extraordinary research needs extraordinary machines: the upgrade project of the LHC, the High-Luminosity LHC (HL-LHC), has the goal of achieving instantaneous luminosities a factor of five larger than the LHC nominal value, and it relies on magnetic fields reaching the level of 12 Tesla. The superconducting niobium-titanium (Nb-Ti) used in the LHC magnets can only bear magnetic fields of up to 9-10 Tesla. Therefore, an alternative solution for the superconducting magnets materials was needed. The key innovative technology to develop superconducting magnets beyond 10 Tesla has been found in the niobium-tin (Nb3Sn)  compound. This compound was actually discovered in 1954, eight years before Nb-Ti, but when the LHC was built, ...

Perovskite-related Ca(Nb,Ti)O3.33

International Nuclear Information System (INIS)

Guevarra, J.; Smaalen, S. van; Daniels, P.; Rotiroti, N.; Lichtenberg, F.

2005-01-01

Crystals of nominal composition Ca(Nb 0.8 Ti 0.2 )O 3.4 , an n = 5 member of the homologous series A n B n O 3n+2 , have been synthesized by floating-zone melting. The material was found to be multiphase consisting also of the n = 6 type. A good single crystal of this n = 6 type was found and the crystal structure at room temperature was determined by X-ray diffraction using synchrotron radiation. Structure refinements indicate a composition of Ca(Nb 0.76 Ti 0.24 )O 3.33 . The crystal structure is monoclinic P2 1 and consists of slabs of corner-sharing (Nb,Ti)O 6 octahedra interrupted by layers of oxygen atoms. Ca atoms within the slabs are 12-fold coordinated whereas those at the borders show irregular coordination geometries. The octahedral distortion is greatest near the borders of the slabs and least near the middle of the slabs. Ti 4+ preferentially occupy octahedral sites in the middle of slabs. The non-stoichiometry in the refined composition and the insulating character of the material may be explained in terms of extra oxygen, vacancies on the cation sites, or by localization of the electrons in the 4d orbitals of Nb at the borders of slabs. (orig.)

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Directory of Open Access Journals (Sweden)

Rui Sun

2016-06-01

Full Text Available We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100 substrates with a TiN buffer layer. A 50-nm-thick (200-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large IcRN product of 3.8 mV, a sharp quasiparticle current rise with a ΔVg of 0.4 mV, and a small subgap leakage current. The junction quality factor Rsg/RN was about 23 for the junction with a Jc of 47 A/cm2 and was about 6 for the junction with a Jc of 3.0 kA/cm2. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200-orientated TiN buffer layer and had a highly crystalline structure with the (200 orientation.

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Energy Technology Data Exchange (ETDEWEB)

Sun, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Makise, Kazumasa; Terai, Hirotaka [Advanced ICT Research Institute, National Institute of Information and Communications Technology (Japan); Zhang, Lu [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Wang, Zhen, E-mail: zwang@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Shanghai Tech University, Shanghai 201210 (China)

2016-06-15

We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large I{sub c}R{sub N} product of 3.8 mV, a sharp quasiparticle current rise with a ΔV{sub g} of 0.4 mV, and a small subgap leakage current. The junction quality factor R{sub sg}/R{sub N} was about 23 for the junction with a J{sub c} of 47 A/cm{sup 2} and was about 6 for the junction with a J{sub c} of 3.0 kA/cm{sup 2}. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

Beta Ti-45Nb and Ti-50Nb alloys produced by powder metallurgy for aerospace application

Energy Technology Data Exchange (ETDEWEB)

Martins, G.V.; Trava-Airoldi, V.J.; Machado, J.P.B., E-mail: givmartins@yahoo.com.br, E-mail: vladimir@las.inpe.br, E-mail: joaopaulo@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Silva, C.R.M., E-mail: cosmeroberto@gmail.com [Universidade de Brasilia (UnB), Brasilia, DF (Brazil); Nunes, C.A., E-mail: cnunes@demar.eel.usp.br [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Polo Urbo Industrial; Borges Junior, L.A., E-mail: borges.jr@itelefonica.com.br [Centro Universitario de Volta Redond (UNIFOA), Volta Redonda, RJ (Brazil)

2009-07-01

Beta titanium alloys parts are used on advanced aerospace systems because of their high strength to weight ratio and excellent corrosion resistance. Production of powder metallurgy titanium alloys components may lead to a substantial reduction in the cost, compared to those produced by conventional cast and wrought processes, because additional working operations and material waste can be avoided. In this work, beta Ti-45Nb and Ti- 50Nb were produced by the blended elemental technique, followed by uniaxial and cold isostatic pressing with subsequent densification by sintering. Sintered samples were characterized for phase composition by XRD, microstructure by SEM, hardness by Vickers indentation, specific mass by the Archimedes method and elastic modulus by resonance ultrasound. The sintered samples presented only the beta phase, higher hardness and lower elastic modulus when compared to Ti6Al4V alloy and experimental specific mass value near theoretical specific mass. These characteristics are adequate for application on several aerospace parts. (author)

Beta Ti-45Nb and Ti-50Nb alloys produced by powder metallurgy for aerospace application

International Nuclear Information System (INIS)

Martins, G.V.; Trava-Airoldi, V.J.; Machado, J.P.B.; Silva, C.R.M.; Nunes, C.A.

2009-01-01

Beta titanium alloys parts are used on advanced aerospace systems because of their high strength to weight ratio and excellent corrosion resistance. Production of powder metallurgy titanium alloys components may lead to a substantial reduction in the cost, compared to those produced by conventional cast and wrought processes, because additional working operations and material waste can be avoided. In this work, beta Ti-45Nb and Ti- 50Nb were produced by the blended elemental technique, followed by uniaxial and cold isostatic pressing with subsequent densification by sintering. Sintered samples were characterized for phase composition by XRD, microstructure by SEM, hardness by Vickers indentation, specific mass by the Archimedes method and elastic modulus by resonance ultrasound. The sintered samples presented only the beta phase, higher hardness and lower elastic modulus when compared to Ti6Al4V alloy and experimental specific mass value near theoretical specific mass. These characteristics are adequate for application on several aerospace parts. (author)

DESIGN, FABRICATION AND TEST OF THE REACT AND WIND, NB(3)SN, LDX FLOATING COIL CONDUCTOR

International Nuclear Information System (INIS)

SMITH, B.A.; MICHAEL, P.C.; MINERVINI, J.V.; TAKAYASU, M.; SCHULTZ, J.H.; GREGORY, E.; PYON, T.; SAMPSON, W.B.; GHOSH, A.; SCANLAN, R.

2000-01-01

The Levitated Dipole Experiment (LDX) is a novel approach for studying magnetic confinement of a fusion plasma. In this approach, a superconducting ring coil is magnetically levitated for up to 8 hours a day in the center of a 5 meter diameter vacuum vessel. The levitated coil, with on-board helium supply, is called the gloating Coil (F-Coil). Although the maximum field at the coil is only 5.3 tesla, a react-and-wind Nb 3 Sn conductor was selected because the relatively high critical temperature will enable the coil to remain levitated while it warms from 5 K to 10 K. Since pre-reacted Nb 3 Sn tape is no longer commercially available, a composite conductor was designed that contains an 18 strand Nb 3 Sn Rutherford cable. The cable was reacted and then soldered into a structural copper channel that completes the conductor and also provides quench protection. The strain state of the cable was continuously controlled during fabrication steps such as: soldering into the copper channel, spooling, and coil winding, to prevent degradation of the critical current. Measurements of strand and cable critical currents are reported, as well as estimates of the effect of fabrication, winding and operating strains on critical current

Multiscale simulation of mechanical properties of TiNb alloy

Science.gov (United States)

Nikonov, A. Yu.

2017-12-01

The article presents a numerical simulation of the mechanical properties of a Ti-Nb β-alloy on three different scales. The ab-initio approach is used to estimate the concentrations of the Ti alloy with required elastic properties. On the basis of molecular dynamics simulation, we calculate the adhesive force between individual particles of the alloy. The calculated dependence is implemented within the movable cellular automata method to determine the mechanical properties of Ti-Nb depending on the interparticle free space.

Shape-memory effect in Ti-Nb alloys

International Nuclear Information System (INIS)

Peradze, T.; Berikashvili, T.; Chelidze, T.; Gorgadze, K.; Bochorishvili, M.; Taktakishvili, M.

2009-01-01

The work deals with the investigation of the binary alloy of titanium with niobium and is aimed at demonstrating the functional-mechanical possibilities of Ti-Nb alloys from the viewpoint of their potential application in practice. The shape-memory effect, super elasticity and reactive stress in alloys of Ti-Nb system were studied. It turned out that the work carried out expanded the interval of Nb content in the investigated alloys from 25.9 to 33.1 wt%. The shape recovery made up not less than 90% at the deformation of 6-8%. The reactive stress reached 350-450 MPa. In the alloys under study another (high-temperature) shape-memory effect was found, and the influence of hydrogen and oxygen on the inelastic properties of alloys was studied. (author)

Structural and vibrational investigations of Nb-doped TiO2 thin films

International Nuclear Information System (INIS)

Uyanga, E.; Gibaud, A.; Daniel, P.; Sangaa, D.; Sevjidsuren, G.; Altantsog, P.; Beuvier, T.; Lee, Chih Hao; Balagurov, A.M.

2014-01-01

Highlights: • We studied the evolutions of structure for TiO 2 thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb 0.1 Ti 0.9 O 2 is smaller than for pure TiO 2 because doped Nb hinders the growth of the TiO 2 grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO 2 films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO 2 which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO 2 thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO 2 by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb 5+ ions into the lattice. The band gap energy of indirect transition of the TiO 2 thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV

Method of treating Ti--Nb--Zr--Ta superconducting alloys

International Nuclear Information System (INIS)

Horiuchi, T.; Monju, Y.; Tatara, I.; Nagai, N.; Hisata, M.; Matsumoto, K.

1975-01-01

A superconducting alloy is formulated from 10 to 50 at. percent Ti, 20 to 50 at. percent Nb, 10 to 40 at. percent Zr, and 5 to 12 at. percent Ta. A Ti--Nb--Zr--Ta superconducting alloy with a fine, non-homogeneous structure is obtained by forming a β solid solution of Ti--Nb--Zr--Ta alloy by heating to a temperature within the β solid solution range, cooling, and then cold working the heated alloy. The cold worked alloy is heated to a temperature within the (β' + β'') alloy to maintain the peritectoid structure, cold worked, then heated to a temperature within the eutectoid range to form a multiphase alloy structure and then cooled and finally cold worked. (U.S.)

On the role of Nb-related sites of an oxidized β-TiNb alloy surface in its interaction with osteoblast-like MG-63 cells

Energy Technology Data Exchange (ETDEWEB)

Jirka, Ivan, E-mail: Ivan.Jirka@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Vandrovcová, Marta [Institute of Physiology, Acad. Sci. CR, v.v.i., Vídeňská 1083, Prague 4 (Czech Republic); Frank, Otakar [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Tolde, Zdeněk [Faculty of Mechanical Engineering, Czech Technical University in Prague, Institute of Materials Engineering, Karlovo nám. 13, Prague 2 (Czech Republic); Plšek, Jan [J. Heyrovský Institute of Physical Chemistry, Acad. Sci. CR, v.v.i. Dolejškova 3, 182 23 Prague 8 (Czech Republic); Luxbacher, Thomas [Anton Paar GmbH, Anton Paar Str. 20, 8054 Graz (Austria); Bačáková, Lucie [Institute of Physiology, Acad. Sci. CR, v.v.i., Vídeňská 1083, Prague 4 (Czech Republic); Starý, Vladimír [Faculty of Mechanical Engineering, Czech Technical University in Prague, Institute of Materials Engineering, Karlovo nám. 13, Prague 2 (Czech Republic)

2013-04-01

β-Stabilized titanium (Ti) alloys containing non-toxic elements, particularly niobium (Nb), are promising materials for the construction of bone implants. Their biocompatibility can be further increased by oxidation of their surface. Therefore, in this study, the adhesion, growth and viability of human osteoblast-like MG 63 cells in cultures on oxidized surfaces of a β-TiNb alloy were investigated and compared with the cell behavior on thermally oxidized Ti, i.e. a metal commonly used for constructing bone implants. Four experimental groups of samples were prepared: Ti or TiNb samples annealed to 600 °C for 60 min in a stream of dry air, and Ti and TiNb samples treated in Piranha solution prior to annealing. We found that on all TiNb-based samples, the cell population densities on days 1, 3 and 7 after seeding were higher than on the corresponding Ti-based samples. As revealed by XPS and Raman spectroscopy, and also by isoelectric point measurements, these results can be attributed to the presence of T-Nb{sub 2}O{sub 5} oxide phase in the surface of the alloy sample, which decreased its negative zeta (ζ)-potential in comparison with zeta (ζ)-potential of the Ti sample at physiological pH. This effect was tentatively explained by the presence of positively charged defects acting as Lewis sites of the surface Nb{sub 2}O{sub 5} phase. Piranha treatment slightly decreases the biocompatibility of the samples, which for the alloy samples may be explained by a decrease in the number of defective sites with this treatment. Thus, the presence of Nb and thermal oxidation of β-stabilized Ti alloys play a significant role in the increased biocompatibility of TiNb alloys. - Highlights: ► T-Nb{sub 2}O{sub 5} and rutile are the main components of the oxidized β-TiNb alloy surface. ► Negative value of ζ potential is reduced by presence of Nb in the alloy surface. ► Less negative ζ potential is beneficial for interaction of the alloy with cells. ► The β-TiNb alloy

Novel transparent conducting oxide: Anatase Ti1-xNb xO2

International Nuclear Information System (INIS)

Furubayashi, Yutaka; Hitosugi, Taro; Yamamoto, Yukio; Hirose, Yasushi; Kinoda, Go; Inaba, Kazuhisa; Shimada, Toshihiro; Hasegawa, Tetsuya

2006-01-01

Single-crystalline Ti 1-x Nb x O 2 (x = 0.2) films of 40 nm thickness were deposited on SrTiO 3 (100) substrates by the pulsed laser deposition (PLD) technique. X-ray diffraction measurement confirmed epitaxial growth of anatase (001) film. The resistivity of Ti 1-x Nb x O 2 films with x ≥ 0.03 is 2-3 x 10 -4 Ω cm at room temperature. The carrier density of Ti 1-x Nb x O 2 , which is almost proportional to the Nb concentration, can be controlled in a range of 1 x 10 19 to 2 x 10 21 cm -3 . Optical measurements revealed that internal transmittance in the visible and near-infrared region for films with x = 0.03 was more than 97%. These results demonstrate that the presently developed anatase Ti 1-x Nb x O 2 is one of the promising candidates for the practical TCOs

Nb-doped rutile TiO₂: a potential anode material for Na-ion battery.

Science.gov (United States)

Usui, Hiroyuki; Yoshioka, Sho; Wasada, Kuniaki; Shimizu, Masahiro; Sakaguchi, Hiroki

2015-04-01

The electrochemical properties of the rutile-type TiO2 and Nb-doped TiO2 were investigated for the first time as Na-ion battery anodes. Ti(1-x)Nb(x)O2 thick-film electrodes without a binder and a conductive additive were prepared using a sol-gel method followed by a gas-deposition method. The TiO2 electrode showed reversible reactions of Na insertion/extraction accompanied by expansion/contraction of the TiO2 lattice. Among the Ti(1-x)Nb(x)O2 electrodes with x = 0-0.18, the Ti(0.94)Nb(0.06)O2 electrode exhibited the best cycling performance, with a reversible capacity of 160 mA h g(-1) at the 50th cycle. As the Li-ion battery anode, this electrode also attained an excellent rate capability, with a capacity of 120 mA h g(-1) even at the high current density of 16.75 A g(-1) (50C). The improvements in the performances are attributed to a 3 orders of magnitude higher electronic conductivity of Ti(0.94)Nb(0.06)O2 compared to that of TiO2. This offers the possibility of Nb-doped rutile TiO2 as a Na-ion battery anode as well as a Li-ion battery anode.

Status of the LHC Superconducting Cable Mass Production

CERN Document Server

Adam, J D; Cavallari, Giorgio; Charifoulline, Z; Denarié, C H; Le Naour, S; Leroy, D F; Oberli, L R; Richter, D; Verweij, A P; Wolf, R

2002-01-01

Six contracts have been placed with industrial companies for the production of 1200 tons of the superconducting (SC) cables needed for the main dipoles and quadrupoles of the Large Hadron Collider (LHC). In addition, two contracts have been placed for the supply of 470 tons of NbTi and 26 tons of Nb sheets. The main characteristic of the specification is that it is functional. This means that the physical, mechanical and electrical properties of strands and cables are specified without defining the manufacturing processes. Facilities for the high precision measurements of the wire and cable properties have been implemented at CERN, such as strand and cable critical current, copper to superconductor ratio, interstrand resistance, magnetisation, RRR at 4.2 K and 1.9 K. The production has started showing that the highly demanding specifications can be fulfilled. This paper reviews the organisation of the contracts, the test facilities installed at CERN, the various types of measurements and the results of the ma...

Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

Science.gov (United States)

Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

2018-04-01

TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

Mechanical Properties of TiTaHfNbZr High-Entropy Alloy Coatings Deposited on NiTi Shape Memory Alloy Substrates

Science.gov (United States)

Motallebzadeh, A.; Yagci, M. B.; Bedir, E.; Aksoy, C. B.; Canadinc, D.

2018-06-01

TiTaHfNbZr high-entropy alloy (HEA) thin films with thicknesses of about 750 and 1500 nm were deposited on NiTi substrates by RF magnetron sputtering using TiTaHfNbZr equimolar targets. The thorough experimental analysis on microstructure and mechanical properties of deposited films revealed that the TiTaHfNbZr films exhibited amorphous and cauliflower-like structure, where grain size and surface roughness increased concomitant with film thickness. More importantly, the current findings demonstrate that the TiTaHfNbZr HEA films with mechanical properties of the same order as those of the NiTi substrate constitute promising biomedical coatings effective in preventing Ni release.

Nb46, 5wt% Ti Eb-melting for AC and DC superconducting applications

International Nuclear Information System (INIS)

Bormio, C.; Ramos, M.J.; Pinatti, D.G.

1990-01-01

This paper reports on the superconductor alloy Nb46, 5wt % Ti which presents the best superconducting and mechanical properties for the systems Nb-Ti. The greatest difficulty in obtaining this alloy is related to the difference between the raw materials melting temperatures, which is about 700 degrees C. As a result the alloy homogeneity as well as Ti desired content, turn to be hard to control. The authors choose an electrode sandwich type, where Nb and Ti sheets are interposed. The electrode dimensions calculation is based on the Ti evaporation rate, energy balance and superficial tension of liquid titanium between Nb sheets. The ingots were electron beam melted. Herein, we present the following ingot results: Ti, intersticial and trace contents compared to international manufactures as well as its mechanical workability. This alloy will be used in NbTi wire production for AC and DC applications. The AC and DC wires are produced by coswaging and codrawing of NbTi bars and C u Ni-tubes for AC wires and Cu-tubes for DC wires. High area reductions of about 2 x 10 8 are reached without intermediate heat treatment, and they are essential since they are precursors of collective pinning centers, responsible for high critical current densities

Development of Ti-12Mo-3Nb alloy for biomedical application; Desenvolvimento da liga Ti-12Mo-3Nb para aplicacao biomedica

Energy Technology Data Exchange (ETDEWEB)

Panaino, J.V.P.; Gabriel, S.B., E-mail: josevicentepanaino@hotmail.co [Centro Universidade de Volta Redonda (UNIFOA), RJ (Brazil); Mei, P. [Universidade Estadual de Campinas (DEMa/UNICAMP), SP (Brazil). Dept. de Materiais; Brum, M.V. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Programa de Engenharia Metalurgica e de Materiais; Nunes, C.A. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia

2010-07-01

The titanium alloys are quite satisfactory for biomedical applications due to their physical, mechanical and biological properties. Recent studies focuses on the development of beta type titanium alloys, composed of toxic elements (Nb, Mo, Ta ,...), because they have more advantages than alpha and alpha + beta (Ti- 6Al-4V) alloys such as lower modulus of elasticity, better plasticity and, moreover, the process variables can be controlled to produce selected results. This project focused on the development and characterization of Ti-12Mo-3Nb alloy in the condition 'as cast' and after thermomechanical treatment. The material was characterized in different conditions by X-ray diffraction, optical microscopy, microhardness measurements and elasticity modulus. The results showed that the forged Ti-12Mo-3Nb alloy showed the best combination of properties, being a promising candidate for use as implant. (author)

Magnetization and loss measurements on Nb3Sn and NbTi strands for ITER and LHC

International Nuclear Information System (INIS)

Foitl, M.

2001-05-01

Recent developments in high energy physics have led to a demand for high magnetic fields which cannot be generated permanently by conventional magnets wound from Cu cables. The acceleration of protons in a ring accelerator up to particle energies of several TeVs or the magnetic confinement of fusion plasmas of sufficient pressure to generate ∼1 GW of fusion power, or even more, are only two examples. To reach beam to beam collision energies of several TeV for hadrons or heavy ions, accelerator magnets have to provide very high magnetic fields which can only be produced by superconducting magnets. In the case of the Large Hadron Collider (LHC), which is planned to be commissioned in the year 2005, the circumference of the beam line is given by the dimensions of the 27 Km Large Electron Positron (LEP) Collider tunnel. Consequently each superconducting arc dipole has to provide a field of 8.36 T to bend 7 TeV protons around the ring. Apart from the total magnitude of the bending field, which necessitates to operate the superconducting NbTi magnets at 1.9 K, very strict demands have to be drawn to the quality of the field components of the guiding field. Actually, any kind of random field error would dilute the 7-on-7 TeV counter-rotating proton beams and degrade their nominal luminosity of 1034 cm -1 s -2 . The main contributions to random field errors are random displacements of the coil positions with respect to nominal design, persistent current magnetization stemming from current imbalances in the superconducting cables and variations of the strand magnetization which come from irregularities in the strand manufacturing process. Since there will be more than one cable manufacturer, there will certainly be a difference between average magnetization values for each of them. Interfilament proximity coupling could make the magnetization higher at low fields, which could also have an influence on the performance of certain magnets in the machine. In the first part of

Carrier compensation mechanism in heavily Nb-doped anatase Ti{sub 1-x}Nb{sub x}O{sub 2+{delta}} epitaxial thin films

Energy Technology Data Exchange (ETDEWEB)

Nogawa, H; Chikamatsu, A; Hirose, Y; Hasegawa, T [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Nakao, S [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Kumigashira, H; Oshima, M, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp [Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656 (Japan)

2011-09-14

We investigated the electronic structures of anatase Ti{sub 1-x}Nb{sub x}O{sub 2+{delta}} (TNO) thin films as a function of Nb concentration x using photoemission spectroscopy (PES) measurements to elucidate the origin of the abrupt decrease in carrier activation in heavily Nb-doped regime. The existing intensity ratio of Nb{sup 5+} evaluated from Nb 3d core-level PES spectra maintained a constant value of {approx}0.8 at x = 0.06-0.3, implying that electron carriers generated by Nb doping are compensated by p-type defects. Ti 2p-3d and O1s-2p resonant PES measurements of x = 0.06-0.3 films revealed that the in-gap states positioned {approx}1 eV below the Fermi level (E{sub F}) have a mixed character of Ti 3d and O 2p orbitals, whereas the states at E{sub F} mainly have a Ti 3d nature. We proposed a carrier compensation mechanism that interstitial oxygen atoms strongly combined with surrounding Nb atoms kill conduction electrons in heavily Nb-doped anatase TiO{sub 2}.

Fatigue and strain effects in NbTi, Nb3Sn, and V2(Hf, Zr) multifilamentary superconductors

International Nuclear Information System (INIS)

Kuroda, T.; Wada, H.; Tachikawa, K.

1988-01-01

The effects of cyclic strain on critical current were studied in NbTi, bronze processed Nb 3 Sn, and composite diffusion processed V 2 (Hf,Zr) multifilamentary wires. No appreciable changes in critical current were found in NbTi wires until just prior to fatigue-induced fracture. Critical current degradation was also not observed in Nb 3 Sn or V 2 (Hf,Zr) as long as the wires were strained below the reversible limit strain. For strains beyond this limit strain the critical current was first degraded by an increasing number of cycles and then remained constant after a certain cycle number was passed

Confining jackets for concrete cylinders using NiTiNb and NiTi shape memory alloy wires

Energy Technology Data Exchange (ETDEWEB)

Choi, Eunsoo; Yoon, Soon-Jong [Department of Civil Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Nam, Tae-Hyun [School of Materials Science and Engineering and ERI, Gyeongsang National University, Jinju, Gyeongnam 600-701 (Korea, Republic of); Cho, Sun-Kyu [School of Civil Engineering, Seoul National University of Technology, Seoul 139-743 (Korea, Republic of); Park, Joonam, E-mail: eunsoochoi@hongik.ac.k [Department of Railroad Structure Research, Korea Railroad Research Institute, Uiwang 437-050, Korea (Korea, Republic of)

2010-05-01

This study used prestrained NiTiNb and NiTi shape memory alloy (SMA) wires to confine concrete cylinders. The recovery stress of the wires was measured with respect to the maximal prestrain of the wires. SMA wires were preelongated during the manufacturing process and then wrapped around concrete cylinders of 150 mmx300 mm ({phi}xL). Unconfined concrete cylinders were tested for compressive strength and the results were compared to those of cylinders confined by SMA wires. NiTiNb SMA wires increased the compressive strength and ductility of the cylinders due to the confining effect. NiTiNb wires were found to be more effective in increasing the peak strength of the cylinders and dissipating energy than NiTi wires. This study showed the potential of the proposed method to retrofit reinforced concrete columns using SMA wires to protect them from earthquakes.

Evaluation of APC NbTi superconductor in a model dipole magnet

International Nuclear Information System (INIS)

Scanlan, R.M.; Lietzke, A.; Royet, J.; Wandesforde, A.; Taylor, C.E.; Wong, J.; Rudziak, M.K.

1993-01-01

The artificial pinning center (APC) approach to NbTi superconductor fabrication offers the potential benefits of higher current density and lower cost than the conventional process for NbTi. We have been evaluating several approaches for fabricating NbTi via the APC approach to determine whether these advantages can be realized in a practical conductor. The study began with the fabrication by several vendors of 10kg size samples which were evaluated as short samples. This was followed by the scale-up of one process to 150mm diameter billets. This material was evaluated first in a solenoid configuration and recently in a one-meter long dipole. We will report here on the results of these coil tests and other characterization results for this new material. We will also describe the plans to continue the scale-up to full size billets and we will discuss the potential cost savings of this approach compared with conventional NbTi fabrication

Corrosion Characteristics of Ti-29Nb-xHf Ternary Alloy for Biomaterials

Energy Technology Data Exchange (ETDEWEB)

Pak, Sun Young; Choi, Han Chul [Chosun Univ., Kwangju (Korea, Republic of)

2015-12-15

The Cp-Ti and Ti-6Al-4V alloys were widely used for dental materials due to their mechanical properties and good corrosion resistance. However, Cp-Ti was known as bio-inert materials, Ti-6Al-4V alloy has a problem such as high Young modulus, potential loss of the surrounding bone, and to the release of potentially toxic ions from the alloy. To overcome this problem, Ti alloys containing Nb and Hf elements have been used for biomaterials due to low toxicity and high corrosion resistance. Especially, alloying element of Nb was known as β phase stabilizer. The β phase alloy was widely used to replace currently used implant materials. The corrosion resistances of Ti-29Nb-xHf ternary alloys were dependent on Hf content in oral environment solution.

Current sharing temperature of NbTi SULTAN samples compared to prediction using a single pinning mechanism parametrization for NbTi strand

International Nuclear Information System (INIS)

Pong, Ian; Vostner, Alexander; Devred, Arnaud; Bessette, Denis; Mitchell, Neil; Bordini, Bernardo; Bottura, Luca; Jewell, Matthew; Long Feng; Wu Yu

2012-01-01

NbTi strands to be used in four of the six ITER poloidal field (PF) coils, all the correction coils (CC) and all the superconducting feeder busbars are being produced in China. Short full-size qualification conductor (cabled and jacketed) samples have been developed at ASIPP and tested at CRPP. Single pinning mechanism parametrization for this Chinese strand (type S2) has been obtained using the Bottura scaling law. The determination of the scaling parameters using a Kramer-type regression method will be described. A comparison between the critical temperature at the operating current and field of a single strand as determined by the parametrization and the current sharing temperature (T CS ) of a few conductor samples tested at the SULTAN facility will be made. The validity and limitation of the estimation will be discussed. The estimated T CS dependence on various (superconducting critical as well as geometric and volumetric) parameters will be assessed using the modelled critical surface. Errors propagated from critical current (I c ) measurements of the strands and parameter fitting, and other uncertainties, will be quantified. (paper)

Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

International Nuclear Information System (INIS)

Li, Qingtang; Lei, Yongping; Fu, Hanguang

2014-01-01

Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously

Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

Energy Technology Data Exchange (ETDEWEB)

Li, Qingtang, E-mail: liqingtang123@126.com; Lei, Yongping, E-mail: yplei@bjut.edu.cn; Fu, Hanguang

2014-10-15

Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously.

Diffusion of titanium and niobium in b.c.c. Ti--Nb alloys

International Nuclear Information System (INIS)

Pontau, A.E.

1978-01-01

The diffusion coefficients for titanium and niobium radioactive tracers were simultaneously measured in Ti, Ti 94 6 Nb 5 4 , Ti 80 4 Nb 19 6 , and Ti 64 3 Nb 35 . 7 over the temperature range from 950 0 C to 1511 0 C using standard lathe sectioning techniques. The samples were initially heat treated by annealing above the α-β phase transition temperature and then either cooling slowly to room temperature or quenching. The room temperature crystal morphology was then examined using x-ray diffraction. Alloy concentrations were chosen both to suppress the β-α transition and to obtain the metastable ω-phase

Structural properties, deformation behavior and thermal stability of martensitic Ti-Nb alloys

Energy Technology Data Exchange (ETDEWEB)

Boenisch, Matthias

2016-06-10

Ti-Nb alloys are characterized by a diverse metallurgy which allows obtaining a wide palette of microstructural configurations and physical properties via careful selection of chemical composition, heat treatment and mechanical processing routes. The present work aims to expand the current state of knowledge about martensite forming Ti-Nb alloys by studying 15 binary Ti-c{sub Nb}Nb (9 wt.% ≤ c{sub Nb} ≤ 44.5 wt.%) alloy formulations in terms of their structural and mechanical properties, as well as their thermal stability. The crystal structures of the martensitic phases, α{sup '} and α'', and the influence of the Nb content on the lattice (Bain) strain and on the volume change related to the β → α{sup '}/α'' martensitic transformations are analyzed on the basis of Rietveld-refinements. The magnitude of the shuffle component of the β → α{sup '}/α'' martensitic transformations is quantified in relation to the chemical composition. The largest transformation lattice strains are operative in Nb-lean alloys. Depending on the composition, both a volume dilatation and contraction are encountered and the volume change may influence whether hexagonal martensite α{sup '} or orthorhombic martensite α'' forms from β upon quenching. The mechanical properties and the deformation behavior of martensitic Ti-Nb alloys are studied by complementary methods including monotonic and cyclic uniaxial compression, nanoindentation, microhardness and impulse excitation technique. The results show that the Nb content strongly influences the mechanical properties of martensitic Ti-Nb alloys. The elastic moduli, hardness and strength are minimal in the vicinity of the limiting compositions bounding the interval in which orthorhombic martensite α'' forms by quenching. Uniaxial cyclic compressive testing demonstrates that the elastic properties of strained samples are different than those of unstrained ones

Effect of Nb on plasticity and oxidation behavior of TiA1Nb intermetallic compound by density functional theory

Institute of Scientific and Technical Information of China (English)

LI Yan-feng; XU Hui; SONG Zhao-quan; MA Song-shan

2010-01-01

Based on the pseudo potential plane-wave method of density functional theory(DFT),Ti1-xNbxA1(x=0,0.062 5,0.083 3,0.125,0.250)crystals' geometry structure,elastic constants,electronic structure and Mulliken populations were calculated,and the effects of doping on the geometric structure,electronic structure and bond strength were systematically analyzed.The results show that the influence of Nb on the geometric structure is little in terms of the plasticity,and with the increase of Nb content,the covalent bond strength remarkably reduces,and Ti-A1,Nb-M(M=Ti,A1)and other hybrid bonds enhance; meanwhile,the peak district increases and the pseudo-energy gap first decreases and then increases,the overall band structure narrows,the covalent bond and direction of bonds reduce.The population analysis also shows that the results are consistent with the electronic structure analysis.The density of states of TiAlNb shows that Nb doping can enhance the activity of Al and benefit the form of Al2O3 film.All the calculations reveal that the room temperature plasticity and the antioxidation properties of the compounds can be improved with the Nb content of 8.33%-12.5%(mole fraction).

Microstructures and phase transformations of Ti-30Zr-xNb (x = 5, 7, 9, 13 at.%) shape memory alloys

Energy Technology Data Exchange (ETDEWEB)

Qu, Wentao; Sun, Xuguang; Yuan, Bifei [School of Mechanical Engineering, Xi' an Shiyou University, Xi' an 710065 (China); Xiong, Chengyang; Zhang, Fei [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Sun, Baohui [Lanzhou Seemine SMA Co. Ltd., Lanzhou 730010 (China)

2016-12-15

The microstructures, phase transformations and shape memory properties of Ti-30Zr-xNb (x = 5, 7, 9, 13 at.%) alloys were investigated. The X-ray diffraction and transmission electron microscopy observations showed that the Ti-30Zr-5Nb, Ti-30Zr-7/9Nb and Ti-30Zr-13Nb alloys were composed of the hcp α′-martensite, orthorhombic α″-martensite and β phases, respectively. The results indicated the enhanced β-stabilizing effect of Nb in Ti-30Zr-xNb alloys than that in Ti-Nb alloys due to the high content of Zr. The differential scanning calorimetry test indicated that the Ti-30Zr-5Nb alloy displayed a reversible transformation with a high martensitic transformation start temperature of 776 K and a reverse martensitic transformation start temperature (A{sub s}) of 790 K. For the Ti-30Zr-7Nb and Ti-30Zr-9Nb alloys, the martensitic transformation temperatures decreased with the increasing Nb content. Moreover, an ω phase transformation occurred in the both alloys upon heating at a temperature lower than the corresponding A{sub s}, which is prompted by more addition of Nb. Although the critical stress in tension of the three martensitic alloys decreased with increasing Nb content, the Ti-30Zr-9Nb alloy showed a critical stress of as high as 300 MPa. Among all the alloys, the Ti-30Zr-9Nb alloy exhibited the maximum shape memory effect of 1.61%, due to the lowest critical stress for the martensite reorientation. - Highlights: •Ti-30Zr-5Nb alloy is composed of hcp α′-martensite with the M{sub s} of 776 K. •Ti-30Zr-7Nb and Ti-30Zr-9Nb alloys are predominated by orthorhombic α″-martensite. •Ti-30Zr-13Nb alloy consists of a single β phase due to the β-stabilizing effect of Nb. •The martensitic transformation temperatures decrease with increasing Nb content. •Ti-30Zr-9Nb alloy shows the maximum shape memory effect of 1.61%.

Introduction of Nonlinear Properties Into Hierachical Models of Nb3Sn Strands

International Nuclear Information System (INIS)

Collins, B.; Krishnan, J.; Arbelaez, D.; Ferracin, P.; Prestemon, S.O.; Godeke, A.; Dietderich, D.R.; Zohdi, T.I.

2011-01-01

The development of computational models representing Rutherford cable formation and deformation is necessary to investigate the strain state in the superconducting filaments in Nb 3 Sn magnets. The wide variety of length scales within accelerator magnets suggests usage of a hierarchical structure within the model. As part of an ongoing investigation at LBNL, a three-dimensional simplified nonlinear multiscale model is developed as a way to extend previous linear elastic versions. The inclusion of plasticity models into the problem formulation allows an improved representation of strand behavior compared to the linear elastic model. This formulation is applied to a single Nb 3 Sn strand to find its effective properties as well as the strain state in the conductor under loading.

Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

Science.gov (United States)

Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

2018-05-01

The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

Tuning electronic structure and optical properties of SrTiO{sub 3} by site-specific doping by Nb with N/B from hybrid functional calculations

Energy Technology Data Exchange (ETDEWEB)

Liu, Yanyu; Zhou, Wei; Wu, Ping, E-mail: pingwu@tju.edu.cn

2017-07-01

In this study, the extensive density functional theory calculations are performed to modify the electronic structure of perovskite SrTiO{sub 3} by doping with Nb and N/B. The unoccupied states induced by the Nb monodoping at the Sr or Ti site, which were passivated in the codoped systems (the substitution of Nb at Ti site with the replacement of N at O site: Nb@Ti/N@O and the substitution of Nb at Sr site with the replacement of B at O site: Nb@Sr/B@O). The charge-compensated donor-acceptor pair codoping creates the new occupied states within the band gap, which yields the absorption edge extend to visible light. And the calculated defect formation energy implies that the codoped systems are energetically favorable under the O-rich condition. Moreover, the band-edge alignment confirmed that the Nb@Ti/N@O system is desirable for the spontaneous water splitting under visible light and the Nb@Sr/B@O system can split water into hydrogen in presence of sacrificial agent. - Highlights: • A systematical study has been employed on SrTiO{sub 3} with the donor-acceptor codoping. • The donor-acceptor pair codoping yields the absorption edge extend to visible light. • The formation energy implies that the codoped systems are favorable under the O-rich condition. • The Nb@Ti/N@O system is desirable for the spontaneous water splitting under visible light. • The Nb@Sr/B@O system can split water into hydrogen in presence of sacrificial agent.

Structural evolution of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} using a series of Ba(Ti{sub 1−5x}Nb{sub 4x})O{sub 3} solid solutions

Energy Technology Data Exchange (ETDEWEB)

Barrientos Hernández, F.R., E-mail: frbh68@hotmail.com [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Lira Hernández, I.A. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Industrial Engineering Department, Technological Institute of Pachuca, Road México-Pachuca km. 87.5, Pachuca de Soto zip code 42080, Hidalgo (Mexico); Gómez Yáñez, C. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Arenas Flores, A. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Cabrera Sierra, R. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Pérez Labra, M. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico)

2014-01-15

Highlights: • The evolution phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} was obtained through the mechanism Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3}. • Addition of niobium can accelerate grain growth of BaTiO{sub 3} ceramics. • Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb{sup 5+} content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} by adding Nb{sub 2}O{sub 5} to perovskite structure of BaTiO{sub 3} was investigated. The compositions Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3} ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO{sub 3}, BaCO{sub 3} and Nb{sub 2}O{sub 5}, were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} which

Microwave-Hydrothermal Synthesis and Characterization of High-Purity Nb Doped BaTiO3 Nanocrystals

Directory of Open Access Journals (Sweden)

A. Khanfekr

2014-01-01

Full Text Available The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and  Nb sources, respectively.  Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3.  In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology.  Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

Optical and semiconductive properties of binary and ternary thin films from the Nb-Ti-O system

Science.gov (United States)

Aperador, W.; Yate, L.; Pinzón, M. J.; Caicedo, J. C.

2018-06-01

A study has been conducted based on the Mott-Schottky model acquisition by potentiodynamic electrochemical impedance spectroscopy, to determine the physical-chemical properties of binary TiO2, Nb2O5 and ternary Nb-Ti-O thin films (semiconductor type) based on Nb,Ti, O elements. The technique used for the study of optical properties was that of spectral transmittance, measurements were performed using a spectrophotometer. The consistency of the impedance data has been studied by calculating the Kramers-Kronig relations. The structural properties were analyzed by XRD patterns; the chemical composition measurements for all thin films were made by using XPS technique. So, in this research the transmittance values change from 72.74% for Nb2O5 to 59.68% for Ti-Nb-O with wavelength around 355 nm. The absorption coefficients for all films were analyzed from 31823.87 cm-1 for Nb2O5 to 91240.90 cm-1 for Nb-Ti-O with wavelength around 355 nm evidencing thus a 65% reduction. The direct band gap it was found that the photon energy (band gap Eg) changes in all films from 3.56 eV for Nb2O5 to 3.96 eV for Ti-Nb-O evidencing a 10% reduction. The extinction coefficient values change in all films from 0.038 cm-1 for Nb2O5 to 0.277 cm-1 for Ti-Nb-O films with wavelength around 355 nm, exhibiting an 86% increasing. Finally, it was observed by the Mott-Schottky analysis that the reference potential (Ag/AgCl) changes for all films from -2.09 V for Nb2O5 to -0.80 V for Ti-Nb-O material showing a 62% reduction.

Mechanical properties and grindability of dental cast Ti-Nb alloys.

Science.gov (United States)

Kikuchi, Masafumi; Takahashi, Masatoshi; Okuno, Osamu

2003-09-01

Aiming at developing a dental titanium alloy with better mechanical properties and machinability than unalloyed titanium, a series of Ti-Nb alloys with Nb concentrations up to 30% was made. They were cast into magnesia-based molds using a dental casting machine and the mechanical properties and grindability of the castings were examined. The hardness of the alloys with Nb concentrations of 5% and above was significantly higher than that of titanium. The yield strength and tensile strength of the alloys with Nb concentrations of 10% and above were significantly higher than those of titanium, while the elongation was significantly lower. A small addition of niobium to titanium did not contribute to improving the grindability of titanium. The Ti-30% Nb alloy exhibited significantly better grindability at low grinding speed with higher hardness, strength, and Young's modulus than titanium, presumably due to precipitation of the omega phase in the beta matrix.

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

Science.gov (United States)

Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

2013-12-01

The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

Determination of the electrostatic potential distribution in Pt/Fe:SrTiO₃/Nb:SrTiO₃ thin-film structures by electron holography.

Science.gov (United States)

Marchewka, Astrid; Cooper, David; Lenser, Christian; Menzel, Stephan; Du, Hongchu; Dittmann, Regina; Dunin-Borkowski, Rafal E; Waser, Rainer

2014-11-10

We determined the electrostatic potential distribution in pristine Pt/Fe:SrTiO3/Nb:SrTiO3 structures by electron holography experiments, revealing the existence of a depletion layer extending into the Nb-doped bottom electrode. Simulations of potential profiles in metal-insulator-metal structures were conducted assuming different types and distributions of dopants. It is found that the presence of acceptor-type dopant concentrations at the Fe:SrTiO3/Nb:SrTiO3 interface with a donor-doped insulating layer provides a good match to the measured profile. Such acceptor-type interface concentrations may be associated with Sr vacancies on the Nb:SrTiO3 side of the bottom interface.

Effect of Nb on glass forming ability and plasticity of (Ti-Cu)-based bulk metallic glasses

International Nuclear Information System (INIS)

Suo, Z.Y.; Qiu, K.Q.; Li, Q.F.; Ren, Y.L.; Hu, Z.Q.

2010-01-01

A Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 alloy. The glass forming ability Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promote the glass forming ability. Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG compared to 0.15% for Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti-Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.

Selective Laser Melting of Ti-45Nb Alloy

Directory of Open Access Journals (Sweden)

Holger Schwab

2015-04-01

Full Text Available Ti-45Nb is one of the potential alloys that can be applied for biomedical applications as implants due to its low Young’s modulus. Ti-45Nb (wt.% gas atomized powders were used to produce bulk samples by selective laser melting with three different parameter sets (energy inputs. A β-phase microstructure consisting of elliptical grains with an enriched edge of titanium was observed by scanning electron microscopy and X-ray diffraction studies. The mechanical properties of these samples were evaluated using hardness and compression tests, which suggested that the strength of the samples increases with increasing energy input within the range considered.

Quench development in magnets made with multifilamentary NbTi cable

International Nuclear Information System (INIS)

Flora, R.H.; Kuchnir, M.; Tollestrup, A.V.

1976-01-01

An experimental study of the normal zone propagation and total resistance as a function of time is described. The normal zone propagation velocity in a single strand was measured as a function of both current and magnetic field with particular interest in the neighborhood of the short sample limit. The study proceeded from measurements in single multifilamentary strands to measurements in 23 strand cables under different cooling environments to final measurements in actual ramping dipole magnets made with this cable. Interpretation of the results led to the determination of safety limits for the Energy Doubler/Saver magnets and to safeguards implemented by an energy dumping circuit which effectively protects these magnets from self-destruction

Mutual Effects of Hydrogenation and Deformation in Ti-Nb Alloys

National Research Council Canada - National Science Library

Zander, D

2002-01-01

...), transmission electron microscopy (TEM), thermal desorption spectroscopy (TDS), and microhardness tests, the influence of hydrogen at high fugacities on the phase stability, desorption behavior, and microhardness in Ti-Nb (20 to 45 wt pct Nb...

Stress-induced phase transformation and room temperature aging in Ti-Nb-Fe alloys

Energy Technology Data Exchange (ETDEWEB)

Cai, S.; Schaffer, J.E. [Fort Wayne Metals Research Products Corp, 9609 Ardmore Ave., Fort Wayne, IN 46809 (United States); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

2017-01-05

Room temperature deformation behavior of Ti-17Nb-1Fe and Ti-17Nb-2Fe alloys was studied by synchrotron X-ray diffraction and tensile testing. It was found that, after proper heat treatment, both alloys were able to recover a deformation strain of above 3.5% due to the Stress-induced Martensite (SIM) phase transformation. Higher Fe content increased the beta phase stability and onset stress for SIM transformation. A strong {110}{sub β} texture was produced in Ti-17Nb-2Fe compared to the {210}{sub β} texture that was observed in Ti-17Nb-1Fe. Room temperature aging was observed in both alloys, where the formation of the omega phase increased the yield strength (also SIM onset stress), and decreased the ductility and strain recovery. Other metastable beta Ti alloys may show a similar aging response and this should draw the attention of materials design engineers.

LHC IR Upgrade Nb-Ti, 120mm Aperture Model Quadrupole Test Results at 1.8K

CERN Document Server

Kirby, G A; Bajko, M; Datskov, V I; Durante, M; Fessia, P; Feuvrier, J; Guinchard, M; Giloux, C; Granieri, P P; Manil, P; Perez, J C; Ravaioli, E; Rifflet, J M; Russenschuck, S; Sahner, T; Segreti, M; Todesco, E; Willering, G

2014-01-01

Over the last five years, the model MQXC quadruple, a 120 mm aperture, 120 T/m, 1.8 m long, Nb-Ti version of the LHC insertion upgrade (due in 2021), has been developed at CERN. The magnet incorporates several novel concepts to extract high levels of heat flux and provide high quality field harmonics throughout the full operating current range. Existing LHC-dipole cable with new, open cable and ground insulation was used. Two, nominally identical 1.8 m long magnets were built and tested at 1.8 K at the CERN SM18 test facility. This paper compares in detail the two magnet tests and presents: quench performance, internal stresses, heat extraction simulating radiation loading in the superconducting coils, and quench protection measurements. The first set of tests highlighted the conflict between high magnet cooling capability and quench protection. The second magnet had additional instrumentation to investigate further this phenomenon. Finally we present test results from a new type of superconducting magnet pro...

Mechanical Properties of a Newly Additive Manufactured Implant Material Based on Ti-42Nb.

Science.gov (United States)

Schulze, Christian; Weinmann, Markus; Schweigel, Christoph; Keßler, Olaf; Bader, Rainer

2018-01-13

The application of Ti-6Al-4V alloy or commercially pure titanium for additive manufacturing enables the fabrication of complex structural implants and patient-specific implant geometries. However, the difference in Young's modulus of α + β-phase Ti alloys compared to the human bone promotes stress-shielding effects in the implant-bone interphase. The aim of the present study is the mechanical characterization of a new pre-alloyed β-phase Ti-42Nb alloy for application in additive manufacturing. The present investigation focuses on the mechanical properties of SLM-printed Ti-42Nb alloy in tensile and compression tests. In addition, the raw Ti-42Nb powder, the microstructure of the specimens prior to and after compression tests, as well as the fracture occurring in tensile tests are characterized by means of the SEM/EDX analysis. The Ti-42Nb raw powder exhibits a dendrite-like Ti-structure, which is melted layer-by-layer into a microstructure with a very homogeneous distribution of Nb and Ti during the SLM process. Tensile tests display Young's modulus of 60.51 ± 3.92 GPa and an ultimate tensile strength of 683.17 ± 16.67 MPa, whereas, under a compressive load, a compressive strength of 1330.74 ± 53.45 MPa is observed. The combination of high mechanical strength and low elastic modulus makes Ti-42Nb an interesting material for orthopedic and dental implants. The spherical shape of the pre-alloyed material additionally allows for application in metal 3D printing, enabling the fabrication of patient-specific structural implants.

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study

International Nuclear Information System (INIS)

Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

2013-01-01

The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5–216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO 2  phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets. (paper)

Reduction of coupling in fine filamentary Cu-NbTi composites by the addition of manganese to the matrix

International Nuclear Information System (INIS)

Kreilick, T.S.; Gregory, E.; Wong, J.; Scanlan, R.M.; Ghosh, A.K.; Sampson, W.B.; Collings, E.W.

1988-01-01

Proximity coupling has been observed in materials containing 4164 filaments in a pure copper matrix designed and fabricated by Supercon Inc. for SSC dipoles. The effect of manganese additions to the copper matrix in reducing this coupling was assessed in this paper. Two multifilamentary NbTi billets were fabricated for SSC inner cable applications. Each composite contains roughly 11,000 filaments embedded in pure copper and copper manganese matrices. Critical current, magnetization, stability, susceptibility and mechanical analyses of these materials indicated no adverse effects from 0.5 wt.% manganese additions to the copper. Results on coupling reduction are evaluated

Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys

International Nuclear Information System (INIS)

Kim, J.I.; Kim, H.Y.; Inamura, T.; Hosoda, H.; Miyazaki, S.

2005-01-01

Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys were investigated by using tensile tests and X-ray diffraction (XRD) measurement. The alloy ingots were fabricated by an arc melting method. The ingots were cold-rolled by a reduction up to 95% in thickness at room temperature. All the alloys were solution-treated at 1173 K for 1.8 ks. The alloys subjected to the solution treatment exhibited large elongations ranging between 28 and 40%. The martensitic transformation temperature decreased by 38 K with 1 at.% increase of Zr content. The maximum recovered strain of 4.3% was obtained in the Ti-22Nb-4Zr(at.%) alloy. Ti-22Nb-(2-4)Zr(at.%) and Ti-22Nb-6Zr(at.%) alloys exhibited stable shape memory effect and superelastic behavior at room temperature, respectively

Tensile and superelastic fatigue characterization of NiTi shape memory cables

Science.gov (United States)

Sherif, Muhammad M.; Ozbulut, Osman E.

2018-01-01

This paper discusses the tensile response and functional fatigue characteristics of a NiTi shape memory alloy (SMA) cable with an outer diameter of 5.5 mm. The cable composed of multiple strands arranged as one inner core and two outer layers. The results of the tensile tests revealed that the SMA cable exhibits good superelastic behavior up to 10% strain. Fatigue characteristics were investigated under strain amplitudes ranging from 3% to 7% and a minimum of 2500 loading cycles. The evolutions of maximum tensile stress, residual strains, energy dissipation, and equivalent viscous damping under a number of loading cycles were analyzed. The fracture surface of a specimen subjected to 5000 loading cycles and 7% strain was discussed. Functional fatigue test results indicated a very high superelastic fatigue life cycle for the tested NiTi SMA cable.

Nb3Sn dipole magnet reacted after winding

International Nuclear Information System (INIS)

Taylor, C.; Scanlan, R.; Peters, C.; Wolgast, R.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Rechen, J.

1984-09-01

A 5 cm bore dia., 1-m-long dipole model magnet was constructed by winding un-reacted cable, followed by reaction and epoxy-impregnation. Experience and test results are described on the 1.7 mm dia. internal-tin wire, the eleven-strand flattened cable, fiberglass insulation, and construction of the magnet. Each half of the magnet has two double-pancake-type windings that were reacted in a single operation. The two double-pancakes were then separately vacuum impregnated after soldering the flexible Nb-Ti leads to the Nb 3 Sn conductors. No iron flux return yoke was used. In initial tests a central field of 8.0 T was reached at 4.4 K. However, evidence from training behavior, and 1.8 K tests indicate that premature quenching, rather than critical current of the cable, limited the field intensity. The magnet was reassembled and more rigidly clamped; additional test results are reported

Cr3+ and Nb5+ co-doped Ti2Nb10O29 materials for high-performance lithium-ion storage

Science.gov (United States)

Yang, Chao; Yu, Shu; Ma, Yu; Lin, Chunfu; Xu, Zhihao; Zhao, Hua; Wu, Shunqing; Zheng, Peng; Zhu, Zi-Zhong; Li, Jianbao; Wang, Ning

2017-08-01

Ti2Nb10O29 is an advanced anode material for lithium-ion batteries due to its large specific capacity and high safety. However, its poor electronic/ionic conductivity significantly limits its rate capability. To tackle this issue, a Cr3+-Nb5+ co-doping is employed, and a series of CrxTi2-2xNb10+xO29 compounds are prepared. The co-doping does not change the Wadsley-Roth shear structure but increases the unit-cell volume and decreases the particle size. Due to the increased unit-cell volumes, the co-doped samples show increased Li+-ion diffusion coefficients. Experimental data and first-principle calculations reveal significantly increased electronic conductivities arising from the formation of impurity bands after the co-doping. The improvements of the electronic/ionic conductivities and the smaller particle sizes in the co-doped samples significantly contribute to improving their electrochemical properties. During the first cycle at 0.1 C, the optimized Cr0.6Ti0.8Nb10.6O29 sample delivers a large reversible capacity of 322 mAh g-1 with a large first-cycle Coulombic efficiency of 94.7%. At 10 C, it retains a large capacity of 206 mAh g-1, while that of Ti2Nb10O29 is only 80 mAh g-1. Furthermore, Cr0.6Ti0.8Nb10.6O29 shows high cyclic stability as demonstrated in over 500 cycles at 10 C with tiny capacity loss of only 0.01% per cycle.

Microstructures and phase relationships in the Ti3Al + Nb system

International Nuclear Information System (INIS)

Kestner-Weykamp, H.T.; Kaufman, M.J.

1989-01-01

Alloys based on the α 2 -Ti 3 Al compound (hexagonal) DO 19 are currently experiencing limited use as advanced aerospace materials. To date, the alloys with the most desirable properties contain additions of β stabilizers, such as Nb, Mo and V, which promote the formation of a two-phase mixture of α 2 +β or α 2 +B2 (where B2 refers to the ordered CsCl structure). Unfortunately, the phase relationships in these systems have not been established in sufficient detail to allow their more widespread application. Recently, there has been a series of investigations aimed at alleviating this deficiency in the ternary Ti-Al-Nb system. These studies have clearly indicated the existence of the ordered B2 phase, which, in the higher Nb alloys, can be retained at room temperature by rapid cooling from the liquid or solid state. The authors describe (TiNb) 3 Al alloys (from 0 to 30 at. pct. Nb) were studies after conventional and nonequilibrium (i.e., rapid solidification) processing with an emphasis on providing further insight into the transformation sequences and phase equilibria in these alloys

Mechanical Properties of a Newly Additive Manufactured Implant Material Based on Ti-42Nb

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Christian Schulze

2018-01-01

Full Text Available The application of Ti-6Al-4V alloy or commercially pure titanium for additive manufacturing enables the fabrication of complex structural implants and patient-specific implant geometries. However, the difference in Young’s modulus of α + β-phase Ti alloys compared to the human bone promotes stress-shielding effects in the implant–bone interphase. The aim of the present study is the mechanical characterization of a new pre-alloyed β-phase Ti-42Nb alloy for application in additive manufacturing. The present investigation focuses on the mechanical properties of SLM-printed Ti-42Nb alloy in tensile and compression tests. In addition, the raw Ti-42Nb powder, the microstructure of the specimens prior to and after compression tests, as well as the fracture occurring in tensile tests are characterized by means of the SEM/EDX analysis. The Ti-42Nb raw powder exhibits a dendrite-like Ti-structure, which is melted layer-by-layer into a microstructure with a very homogeneous distribution of Nb and Ti during the SLM process. Tensile tests display Young’s modulus of 60.51 ± 3.92 GPa and an ultimate tensile strength of 683.17 ± 16.67 MPa, whereas, under a compressive load, a compressive strength of 1330.74 ± 53.45 MPa is observed. The combination of high mechanical strength and low elastic modulus makes Ti-42Nb an interesting material for orthopedic and dental implants. The spherical shape of the pre-alloyed material additionally allows for application in metal 3D printing, enabling the fabrication of patient-specific structural implants.

High Temperature Mechanical Constitutive Modeling of a High-Nb TiAl Alloy

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DONG Chengli

2018-02-01

Full Text Available Uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep experiments of a novel high-Nb TiAl alloy (i.e. Ti-45Al-8Nb-0.2W-0.2B-0.02Y (atom fraction/% were conducted at 750℃ to obtain its tested data and curves. Based on Chaboche visco-plasticity unified constitutive model, Ohno-Wang modified non-linear kinematic hardening was introduced in Chaboche constitutive model to describe the cyclic hardening/softening, and Kachanov damage was coupled in Chaboche constitutive model to characterize the accelerated creep stage. The differential equations of the constitutive model discretized by explicit Euler method were compiled in to ABAQUS/UMAT to simulate the mechanical behavior of high-Nb TiAl alloy at different test conditions. The results show that Chaboche visco-plasticity unified constitutive model considering both Ohno-Wang modified non-linear kinematic hardening and Kachanov damage is able to simulate the uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep behavior of high-Nb TiAl alloy and has high accuracy.

Effect of Ti and Nb Addition on Precipitation and Sensitization Behavior in Ferritic Stainless Steel Welded Joint

International Nuclear Information System (INIS)

Kim, Jong Min; Lee, Hae Woo

2013-01-01

The precipitation and sensitization characteristics in AISI436 weld metal were investigated in different chemical composition ranges of Ti and Nb content. We manufactured four welding wires made of 0-0.2 wt% of Ti and 0-1.0 wt% of Nb and did flux cored arc welding. After heat treatment at 900 °C for 20 hours, we made a Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test, Electron Backscattering Diffraction and SEM. The DL-EPR test revealed that as the amount of addition of Ti and Nb rose, the degree of sensitization fell. The microstructure became more refined, and Cr carbide formed at the grain boundary that had no addition of Ti and Nb. Furthermore, in the specimen with the addition of Ti, Nb, the Ti, Nb carbide and nitride were precipitated in the intergranular boundary, and the laves phase was precipitated at the grain boundary.

Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications

Science.gov (United States)

Park, Seon-Yeong; Choe, Han-Cheol

2018-02-01

In this study, Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetrons sputtering for dental applications were studied using different experimental techniques. Mn coating films were formed on Ti-29Nb-xHf alloys by a radio frequency magnetron sputtering technique for 0, 1, 3, and 5 min at 45 W. The microstructure, composition, and phase structure of the coated alloys were examined by optical microscopy, field emission scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The microstructure of Ti-29Nb alloy showed α" phase in the needle-like structure and Ti-29Nb-15Hf alloy showed β phase in the equiaxed structure. As the sputtering time increased, the circular particles of Mn coatings on the Ti-29Nb alloy increased at inside and outside surfaces. As the sputtering time increased, [Mn + Ca/P] ratio of the plasma electrolytic oxidized films in Ti- 29Nb-xHf alloys increased. The corrosion potential (Ecorr) of Mn coatings on the Ti-29Nb alloy showed higher than that of Mn coatings on the Ti-29Nb-15Hf alloy. The passive current density (Ipass) of the Mn coating on the Ti-29Nb alloy and Mn coatings on the Ti-29Nb-15Hf alloy was less noble than the non-Mn coated Ti-29Nb and Ti-29Nb-15Hf alloys surface.

Impulse Pressuring Diffusion Bonding of TiC Cermet to Stainless Steel Using Ti/Nb Interlayer

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LI Jia

2017-03-01

Full Text Available Impulse pressuring diffusion bonding(IPDB and constant pressuring diffusion bonding(CPDB of TiC cermet to 304 stainless steel(304SS using Ti/Nb interlayer was carried out at 890℃ under a impulse pressuring of 2-10MPa and a constant pressuring of 10MPa within a duration of only 4-12min, and a robust metallurgical bonding was achieved. Microstructure characterization and shear performance of the IPDB and CPDB joints were analyzed by SEM, EDS, XRD and shearing test. The results show that the interface phases in those two kinds of joints are similar, which are mainly σ phase,(β-Ti, Nb and α+β-Ti solid solution. When the joint is bonded for 10min, shear strength of TiC/304SS CPDB joints is 55.6MPa, while the shear strength of IPDB joints reaches 110MPa. The fracture of CPDB joints is TiC cermet fracture, while that of IPDB joints is mixed fracture by alternated between TiC cermet and reaction layer.

Emergence of Nb-Ti as supermagnet material

Energy Technology Data Exchange (ETDEWEB)

Berlincourt, T G

1987-06-01

The discovery and emergence of Nb-Ti as a high field superconductor are reviewed. The prehistory and setting for its discovery are described, and an anecdotal history follows its development up to the first successful large scale applications.

The system K2NbF7-K2TiF6-KCl

International Nuclear Information System (INIS)

Kamenskaya, L.A.; Matveev, A.M.

1984-01-01

Using visual-polythermal and thermographical methods the ternary system K 2 NbF 7 -K 2 TiE 6 -KCl has been studied. Crystallization fields of initial components and the field of solid solutions of double compounds K 3 NbClF 7 and K 3 TiClF 6 are outlined. Ternary eutectics at 654 deg C, having the composition K 2 NbF 6 -41, K 2 TiP 6 -41, KCl-18 mol.%, is determined. Potassium fluoroniobate and fluorotitanate form continuous solid solutions unstable in the presence of the third component, potassium chloride

In vitro corrosion behaviour of Ti-Nb-Sn shape memory alloys in Ringer's physiological solution.

Science.gov (United States)

Rosalbino, F; Macciò, D; Scavino, G; Saccone, A

2012-04-01

The nearly equiatomic Ni-Ti alloy (Nitinol) has been widely employed in the medical and dental fields owing to its shape memory or superelastic properties. The main concern about the use of this alloy derives form the fact that it contains a large amount of nickel (55% by mass), which is suspected responsible for allergic, toxic and carcinogenic reactions. In this work, the in vitro corrosion behavior of two Ti-Nb-Sn shape memory alloys, Ti-16Nb-5Sn and Ti-18Nb-4Sn (mass%) has been investigated and compared with that of Nitinol. The in vitro corrosion resistance was assessed in naturally aerated Ringer's physiological solution at 37°C by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as a function of exposure time, and potentiodynamic polarization curves. Corrosion potential values indicated that both Ni-Ti and Ti-Nb-Sn alloys undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Ti-18Nb-5Sn alloy. Significantly low anodic current density values were obtained from the polarization curves, indicating a typical passive behaviour for all investigated alloys, but Nitinol exhibited breakdown of passivity at potentials above approximately 450 mV(SCE), suggesting lower corrosion protection characteristics of its oxide film compared to the Ti-Nb-Sn alloys. EIS studies showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The obtained EIS spectra were analyzed using an equivalent electrical circuit representing a duplex structure oxide film, composed by an outer and porous layer (low resistance), and an inner barrier layer (high resistance) mainly responsible for the alloys corrosion resistance. The resistance of passive film present on the metals' surface

Emergence of Nb-Ti as supermagnet material

International Nuclear Information System (INIS)

Berlincourt, T.G.

1987-01-01

The discovery and emergence of Nb-Ti as a high field superconductor are reviewed. The prehistory and setting for its discovery are described, and an anecdotal history follows its development up to the first successful large scale applications. (author)

Fabrication and component testing results for a Nb3Sn dipole magnet

International Nuclear Information System (INIS)

Dell'Orco, D.; Scanlan, R.M.; Taylor, C.E.; Lietzke, A.; Caspi, S.; van Oort, J.M.; McInturff, A.D.

1994-10-01

At present, the maximum field achieved in accelerator R ampersand D dipoles is slightly over 10T, with NbTi conductor at 1.8 K. Although Nb 3 Sn has the potential to achieve much higher fields, none of the previous dipoles constructed from Nb 3 Sn have broken the 10T barrier. We report here on the construction of a dipole with high current density Nb 3 Sn with a predicted short sample limit of 13T. A wind and react technique, followed by epoxy impregnation of the fiberglass insulated coils, was used. The problems identified with the use of Nb 3 SD in earlier dipole magnets were investigated in a series of supplemental tests. This includes measurement of the degradation of J c with transverse strain, cabling degradation, joint resistance measurements, and epoxy strength tests. In addition, coff assembly techniques were developed to ensure that adequate prestress could be applied without damaging the reacted Nb 3 Sn cable. We report here the results of these tests and the construction status of this 50 mm bore dipole

Voltage spikes in Nb3Sn and NbTi strands

International Nuclear Information System (INIS)

Bordini, B.; Ambrosio, G.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Orris, D.; Tartaglia, M.; Tompkins, J.C.; Turrioni, D.; Yamada, R.; Zlobin, A.V.; Fermilab

2005-01-01

As part of the High Field Magnet program at Fermilab several NbTi and Nb 3 Sn strands were tested with particular emphasis on the study of voltage spikes and their relationship to superconductor instabilities. The voltage spikes were detected under various experimental conditions using voltage-current (V-I) and voltage-field (V-H) methods. Two types of spikes, designated ''magnetization'' and ''transport current'' spikes, have been identified. Their origin is most likely related to magnetization flux jump and transport current redistribution, respectively. Many of the signals observed appear to be a combination of these two types of spikes; the combination of these two instability mechanisms should play a dominant role in determining the minimum quench current

Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

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Edgar Valenzuela

2013-01-01

Full Text Available Nowadays, one of the major issues of the PEMFC concerns the durability. Historically, carbon has been used as a catalyst support in PEMFC; nevertheless, under the environmental conditions of the cell, the carbon is oxidized, leaving the catalyst unsupported. In order to increase the stability and durability of the catalyst in the PEMFC, a novel nanostructured metallic oxide support is proposed. In this work, TiO2 was doped with Nb to obtain a material that combines chemical stability, high surface area, and an adequate electronic conductivity in order to be a successful catalyst support candidate for long-term PEMFC applications. The TiO2-Nb nanostructured catalyst support was physically and electrochemically characterized. According to the results, the TiO2-Nb offers high surface area and good particle dispersion; also, the electrochemical activity and stability of the support were evaluated under high potential conditions, where the TiO2-Nb proved to be much more stable than carbon.

Porous TiNb24O62 microspheres as high-performance anode materials for lithium-ion batteries of electric vehicles.

Science.gov (United States)

Yang, Chao; Deng, Shengjue; Lin, Chunfu; Lin, Shiwei; Chen, Yongjun; Li, Jianbao; Wu, Hui

2016-11-10

TiNb 24 O 62 is explored as a new anode material for lithium-ion batteries. Microsized TiNb 24 O 62 particles (M-TiNb 24 O 62 ) are fabricated through a simple solid-state reaction method and porous TiNb 24 O 62 microspheres (P-TiNb 24 O 62 ) are synthesized through a facile solvothermal method for the first time. TiNb 24 O 62 exhibits a Wadsley-Roth shear structure with a structural unit composed of a 3 × 4 octahedron-block and a 0.5 tetrahedron at the block-corner. P-TiNb 24 O 62 with an average sphere size of ∼2 μm is constructed by nanoparticles with an average size of ∼100 nm, forming inter-particle pores with a size of ∼8 nm and inter-sphere pores with a size of ∼55 nm. Such desirable porous microspheres are an ideal architecture for enhancing the electrochemical performances by shortening the transport distance of electrons/Li + -ions and increasing the reaction area. Consequently, P-TiNb 24 O 62 presents outstanding electrochemical performances in terms of specific capacity, rate capability and cyclic stability. The reversible capacities of P-TiNb 24 O 62 are, respectively, as large as 296, 277, 261, 245, 222, 202 and 181 mA h g -1 at 0.1, 0.5, 1, 2, 5, 10 and 20 C, which are obviously larger than those of M-TiNb 24 O 62 (258, 226, 210, 191, 166, 147 and 121 mA h g -1 ). At 10 C, the capacity of P-TiNb 24 O 62 still remains at 183 mA h g -1 over 500 cycles with a decay of only 0.02% per cycle, whereas the corresponding values of M-TiNb 24 O 62 are 119 mA h g -1 and 0.04%. These impressive results indicate that P-TiNb 24 O 62 can be a promising anode material for lithium-ion batteries of electric vehicles.

The impact of Ti and temperature on the stability of Nb5Si3 phases: a first-principles study.

Science.gov (United States)

Papadimitriou, Ioannis; Utton, Claire; Tsakiropoulos, Panos

2017-01-01

Nb-silicide based alloys could be used at T > 1423 K in future aero-engines. Titanium is an important additive to these new alloys where it improves oxidation, fracture toughness and reduces density. The microstructures of the new alloys consist of an Nb solid solution, and silicides and other intermetallics can be present. Three Nb 5 Si 3 polymorphs are known, namely αNb 5 Si 3 ( tI 32 Cr 5 B 3 -type, D8 l ), βNb 5 Si 3 ( tI 32 W 5 Si 3 -type, D8 m ) and γNb 5 Si 3 ( hP 16 Mn 5 Si 3 -type, D8 8 ). In these 5-3 silicides Nb atoms can be substituted by Ti atoms. The type of stable Nb 5 Si 3 depends on temperature and concentration of Ti addition and is important for the stability and properties of the alloys. The effect of increasing concentration of Ti on the transition temperature between the polymorphs has not been studied. In this work first-principles calculations were used to predict the stability and physical properties of the various Nb 5 Si 3 silicides alloyed with Ti. Temperature-dependent enthalpies of formation were computed, and the transition temperature between the low (α) and high (β) temperature polymorphs of Nb 5 Si 3 was found to decrease significantly with increasing Ti content. The γNb 5 Si 3 was found to be stable only at high Ti concentrations, above approximately 50 at. % Ti. Calculation of physical properties and the Cauchy pressures, Pugh's index of ductility and Poisson ratio showed that as the Ti content increased, the bulk moduli of all silicides decreased, while the shear and elastic moduli and the Debye temperature increased for the αNb 5 Si 3 and γNb 5 Si 3 and decreased for βNb 5 Si 3 . With the addition of Ti the αNb 5 Si 3 and γNb 5 Si 3 became less ductile, whereas the βNb 5 Si 3 became more ductile. When Ti was added in the αNb 5 Si 3 and βNb 5 Si 3 the linear thermal expansion coefficients of the silicides decreased, but the anisotropy of coefficient of thermal expansion did not change significantly.

Development of Ti-12Mo-3Nb alloy for biomedical application

International Nuclear Information System (INIS)

Panaino, J.V.P.; Gabriel, S.B.; Mei, P.; Brum, M.V.; Nunes, C.A.

2010-01-01

The titanium alloys are quite satisfactory for biomedical applications due to their physical, mechanical and biological properties. Recent studies focuses on the development of beta type titanium alloys, composed of toxic elements (Nb, Mo, Ta ,...), because they have more advantages than alpha and alpha + beta (Ti- 6Al-4V) alloys such as lower modulus of elasticity, better plasticity and, moreover, the process variables can be controlled to produce selected results. This project focused on the development and characterization of Ti-12Mo-3Nb alloy in the condition 'as cast' and after thermomechanical treatment. The material was characterized in different conditions by X-ray diffraction, optical microscopy, microhardness measurements and elasticity modulus. The results showed that the forged Ti-12Mo-3Nb alloy showed the best combination of properties, being a promising candidate for use as implant. (author)

XPS study on the electronic structure of hydrided Ti-V, Ti-Nb and Ti-Mo alloys

International Nuclear Information System (INIS)

Tanaka, Kazuhide; Aoki, Hiromasa

1989-01-01

Effects of hydrogenation on the core and valence electronic structures of β(bcc)-stabilized Ti-25at%V, Ti-50at%Nb and Ti-20at%Mo alloys are studied with XPS technique using monochromatized Al K α radiation. Small but uniform binding-energy shifts are observed upon hydrogenation for all the core spectra measured. Their valence-band spectra are significantly distorted, providing an evidence of the formation of metal-hydrogen bonding bands in these Ti alloys. Interrelations between the core binding-energy shifts and the valence-band distortion are discussed. (orig.)

Determination of the electrostatic potential distribution in Pt/Fe:SrTiO3/Nb:SrTiO3 thin-film structures by electron holography

Science.gov (United States)

Marchewka, Astrid; Cooper, David; Lenser, Christian; Menzel, Stephan; Du, Hongchu; Dittmann, Regina; Dunin-Borkowski, Rafal E.; Waser, Rainer

2014-11-01

We determined the electrostatic potential distribution in pristine Pt/Fe:SrTiO3/Nb:SrTiO3 structures by electron holography experiments, revealing the existence of a depletion layer extending into the Nb-doped bottom electrode. Simulations of potential profiles in metal-insulator-metal structures were conducted assuming different types and distributions of dopants. It is found that the presence of acceptor-type dopant concentrations at the Fe:SrTiO3/Nb:SrTiO3 interface with a donor-doped insulating layer provides a good match to the measured profile. Such acceptor-type interface concentrations may be associated with Sr vacancies on the Nb:SrTiO3 side of the bottom interface.

Influence of different grained powders and pellets made of Niobium and Ti-42Nb on human cell viability

Energy Technology Data Exchange (ETDEWEB)

Markhoff, Jana, E-mail: markhoffj@gmail.com [University Medicine Rostock, Department of Orthopedics, Biomechanics and Implant Technology Laboratory, Doberaner Strasse 142, 18057 Rostock (Germany); Weinmann, Markus [H.C. Starck Tantalum and Niobium GmbH, Im Schleeke 78-91, 38642 Goslar (Germany); Schulze, Christian; Bader, Rainer [University Medicine Rostock, Department of Orthopedics, Biomechanics and Implant Technology Laboratory, Doberaner Strasse 142, 18057 Rostock (Germany)

2017-04-01

Nowadays, biomaterials can be used to maintain or replace several functions of the human body if necessary. Titanium and its alloys, i.e. Ti6Al4V are the most common materials (70 to 80%) used for structural orthopedic implants due to their unique combination of good mechanical properties, corrosion resistance and biocompatibility. Addition of β-stabilizers, e.g. niobium, can improve the mechanical properties of such titanium alloys further, simultaneously offering excellent biocompatibility. In this in vitro study, human osteoblasts and fibroblasts were cultured on different niobium specimens (Nb Amperit, Nb Ampertec), Nb sheets and Ti-42Nb (sintered and 3D-printed by selective laser melting, SLM) and compared with forged Ti6Al4V specimens. Furthermore, human osteoblasts were incubated with particulates of the Nb and Ti-42Nb specimens in three concentrations over four and seven days to imitate influence of wear debris. Thereby, the specimens with the roughest surfaces, i.e. Ti-42Nb and Nb Ampertec, revealed excellent and similar results for both cell types concerning cell viability and collagen synthesis superior to forged Ti6Al4V. Examinations with particulate debris disclosed a dose-dependent influence of all powders with Nb Ampertec showing the highest decrease of cell viability and collagen synthesis. Furthermore, interleukin synthesis was only slightly increased for all powders. In summary, Nb Ampertec (sintered Nb) and Ti-42Nb materials seem to be promising alternatives for medical applications compared to common materials like forged or melted Ti6Al4V. - Highlights: • Titanium and its alloys most common materials used for structural orthopedic implants • Addition of β-stabilizers to improve mechanical properties • Roughest surfaces, Nb ampertec and Ti-42Nb, with excellent results concerning cell viability and collagen synthesis • No cell-specific differences between human osteoblasts and fibroblasts • Niobium based powders with dose- and partly

Microstructure and mechanical properties of the NiNbZrTiAl amorphous alloys with 10 and 25 at.% Nb content.

Science.gov (United States)

Czeppe, T; Ochin, P; Sypień, A; Major, L

2010-03-01

The results of investigation of two different Ni-based glasses with compositions Ni(58)Nb(10)Zr(13)Ti(12)Al(7) and Ni(58)Nb(25)Zr(8)Ti(6)Al(3) are presented. The structure of the melt spun ribbons was amorphous. The supercooled liquid range decreased and primary crystallization temperature increased with increasing Nb content while the parameter T(g)/T(m) slightly increased. The crystallization process proceeded in a different way. The ribbon containing 10 at.% Nb showed typical primary crystallization of the 50 nm grains of the NiTi(Nb) cubic phase; the ribbon containing 25 at.% of Nb revealed high thermal stability of the amorphous phase, which crystallized only in a small amount in the range of primary crystallization, preserving large fraction of the amorphous phase even high above the end of the crystallization. The tensile load-displacement curves were also different. In both cases, the ribbons revealed quite a large range of the plastic elongation. The ribbon containing 10% Nb showed stress relaxation and was maximally elongated up to 0.6. The ribbon with 25 at.% Nb revealed a hardening effect and the slightly smaller maximal elongation following it. The microstructure of the deformed specimens showed deformation bands parallel to the tensile axis, microcracks formation along shear bands and river-like pattern at the fracture surfaces. In both cases, high resolution electron microscope did not reveal any crystallization after deformation.

Characteristics of Cu stabilized Nb3Al strands with low Cu ratio

Energy Technology Data Exchange (ETDEWEB)

Kikuchi, A.; Yamada, R.; Barzi, E.; Kobayashi, M.; Lamm, M.; Nakagawa, K.; Sasaki, K.; Takeuchi, T.; Turrioni, D.; Zlobin, A.V.; /NIMC, Tsukuba /Fermilab /Hitachi, Tsuchiura Works /KEK, Tsukuba

2008-12-01

Characteristics of recently developed F4-Nb{sub 3}Al strand with low Cu ratio are described. The overall J{sub c} of the Nb{sub 3}Al strand could be easily increased by decreasing of the Cu ratio. Although the quench of a pulse-like voltage generation is usually observed in superconducting unstable conductor, the F4 strand with a low Cu ratio of 0.61 exhibited an ordinary critical transition of gradual voltage generation. The F4 strand does not have magnetic instabilities at 4.2 K because of the tantalum interfilament matrix. The overall J{sub c} of the F4 strand achieved was 80-85% of the RRP strand. In the large mechanical stress above 100 MPa, the overall J{sub c} of the F4 strand might be comparable to that of high J{sub c} RRP-Nb{sub 3}Sn strands. The Rutherford cable with a high packing factor of 86.5% has been fabricated using F4 strands. The small racetrack magnet, SR07, was also fabricated by a 14 m F4 cable. The quench current, I{sub q}, of SR07 were obtained 22.4 kA at 4.5 K and 25.2 kA at 2.2 K. The tantalum matrix Nb{sub 3}Al strands are promising for the application of super-cooled high-field magnets as well as 4.2 K operation magnets.

Effect of thermo-mechanical processing on the material properties at low temperature of a large size Al-Ni stabilized Nb-Ti/Cu superconducting cable

Science.gov (United States)

Langeslag, S. A. E.; Curé, B.; Sgobba, S.; Dudarev, A.; ten Kate, H. H. J.; Neuenschwander, J.; Jerjen, I.

2014-01-01

For future high-resolution particle experiments, a prototype for a 60 kA at 5 T, 4.2 K class conductor is realized by co-extrusion of a large, 40-strand Nb-Ti/Cu superconducting cable with a precipitation type Al-0.1wt.%Ni stabilizer. Microalloying with nickel contributes to the strength of the stabilizer, and avoids significant degradation in residual resistivity ratio, owing to its low solid solubility in aluminum. Sections of the conductor are work hardened to increase the mechanical properties of the as-extruded temper. Mechanical and resistivity characteristics are assessed as function of the amount of work hardening, at room temperature as well as at 4.2 K. Thermal treatments, like resin curing after coil winding, can cause partial annealing of the cold-worked material and reverse the strengthening effect. However, targeted thermal treatments, applied at relatively low temperature can result in precipitation hardening. The depletion of nickel in the aluminum-rich matrix around the precipitates results in an increased strength and a decreased effect of nickel on the thermal and electrical resistivity of the material. The present work aims at identifying an optimal work hardening sequence, and an optimal thermal treatment, possibly coinciding with a suitable coil resin curing cycle, for the Al-Ni stabilized superconductor.

Fabrication and characterization of perovskite-type solar cells with Nb-doped TiO{sub 2} layers

Energy Technology Data Exchange (ETDEWEB)

Saito, Jo; Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Suzuki, Atsushi; Akiyama, Tsuyoshi [The University of Shiga Prefecture, Hikone, Shiga 522-8533 (Japan)

2016-02-01

Organic-inorganic hybrid heterojunction solar cells containing perovskite CH{sub 3}NH{sub 3}PbI{sub 3} using Nb-doped TiO{sub 2} as an electron-transporting layer were fabricated and characterized. Nb-doped TiO{sub 2} layer showed an improvement of the short-circuit current density and power conversion efficiency using Ti{sub 0.95}Nb{sub 0.05}O{sub 2}.

Study on properties of stress relaxation for NiTiNb shape memory alloy

International Nuclear Information System (INIS)

Zhou Xuchang; Mo Huaqiang; Zeng Guangting; Shen Baoluo; Huo Yongzhong

2002-01-01

Stress relaxation tests at high temperature are performed for NiTiNb shape memory alloy to obtain the properties of stress relaxation. The relaxation curve fitted with the expression, which is deduced based on the relation between the relaxation and the creep. With the aid of experimental data, relaxation characteristic coefficient and remaining stress ratio are obtained, which characterize the relaxation behavior. The results of the study show that stress relaxation would be more evident with the higher temperature and/or greater initial stress. NiTiNb alloy has good relaxation resistance in the temperature range 300-400 degree C and the initial stress range 260-360 MPa. NiTiNb has better properties to resist relaxation than NiTiFe, therefore it is more applicable to work at high temperature

AC losses and stability on large cable-in-conduit superconductors

Science.gov (United States)

Bruzzone, Pierluigi

1998-12-01

The cable-in-conduit superconductors are preferred for applications where the AC losses and stability are a major concern, e.g., fusion magnets and SMES. A review of coupling currents loss results for both NbTi and Nb 3Sn cable-in-conduit conductors (CICC) is presented and the AC loss relevant features are listed, with special emphasis for the role of the interstrand resistance and strand coating. The transient stability approach for CICCs is discussed and the analytical models are quoted as well as the relevant experimental database. The likely spectrum of transient disturbance in CICC is reviewed and the need to account for interstrand current sharing in the design is outlined. Eventually a practical criterion for the interstrand resistance is proposed to link the stability and AC loss design.

A unique cabling designed to produce Rutherford-type superconducting cable for the SSC project

International Nuclear Information System (INIS)

Grisel, J.; Royet, J.M.; Scanlan, R.M.; Armer, R.

1988-08-01

Up to 25,000 Km of keystoned flat cable must be produced for the SSC project. Starting from a specification developed by Lawrence Berkeley Laboratory (LBL), a special cabling machine has been designed by Dour Metal. It has been designed to be able to run at a speed corresponding to a maximum production rate of 10 m/min. This cabling machine is the key part of the production line which consists of a precision Turkshead equipped with a variable power drive, a caterpillar, a dimensional control bench, a data acquisition system, and a take-up unit. The main features of the cabling unit to be described are a design with nearly equal path length between spool and assembling point for all the wires, and the possibility to run the machine with several over- or under-twisting ratios between cable and wires. These requirements led Dour Metal to the choice of an unconventional mechanical concept for a cabling machine. 4 refs., 2 figs

Voltage spikes in Nb3Sn and NbTi strands

Energy Technology Data Exchange (ETDEWEB)

Bordini, B.; Ambrosio, G.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Lamm, M.J.; Orris, D.; Tartaglia, M.; Tompkins, J.C.; Turrioni, D.; Yamada, R.; Zlobin,; /Fermilab

2005-09-01

As part of the High Field Magnet program at Fermilab several NbTi and Nb{sub 3}Sn strands were tested with particular emphasis on the study of voltage spikes and their relationship to superconductor instabilities. The voltage spikes were detected under various experimental conditions using voltage-current (V-I) and voltage-field (V-H) methods. Two types of spikes, designated ''magnetization'' and ''transport current'' spikes, have been identified. Their origin is most likely related to magnetization flux jump and transport current redistribution, respectively. Many of the signals observed appear to be a combination of these two types of spikes; the combination of these two instability mechanisms should play a dominant role in determining the minimum quench current.

The effect of Ti(CN/TiNb(CN coating on erosion–corrosion resistance

Directory of Open Access Journals (Sweden)

William Aperador Chaparro

2012-05-01

Full Text Available The goal of this work was to study electrochemical behaviour in corrosion-erosion conditions for Ti(CN/TiNb(CN multilayer coatings having 1, 50, 100, 150 and 200 bilayer periods on AISI 4140 steel substrates by using a multi-target magnetron reactive sputtering device, with an r.f. source (13.56 MHz, two cylindrical magnetron cathodes and two stoichiometric TiC and Nb targets. The multi-layers were evaluated by comparing them to corrosion, erosion and erosion corrosion for a 30º impact angle in a solution of 0.5 M NaCl and silica, analysing the effect of impact angle and the number of bilayers on these coatings’ corrosion resistance. The electrochemical characterisation was performed using electrochemical impedance spectroscopy for analysing corrosion surface; surface morphology was characterised by using a high-resolution scanning electron microscope (SEM. The results showed a de-creased corrosion rate for multilayer systems tested at 30°.

Major enhancement of the thermoelectric performance in Pr/Nb-doped SrTiO3 under strain

KAUST Repository

Amin, B.

2013-07-16

The electronic structure and thermoelectric properties of strained (biaxially and uniaxially) Sr0.95Pr0.05TiO3 and SrTi0.95Nb0.05O3 are investigated in the temperature range from 300 K to 1200 K. Substitutions of Pr at the Sr site and Nb at the Ti site generate n-type doping and thus improve the thermoelectric performance as compared to pristine SrTiO3. Further enhancement is achieved by the application of strain, for example, of the Seebeck coefficient by 21% for Sr0.95Pr0.05TiO3 and 10% for SrTi0.95Nb0.05O3 at room temperature in the case of 5% biaxial strain. At 1200 K, we predict figures of merit of 0.58 and 0.55 for 2.5% biaxially strained Sr0.95Pr0.05TiO3 and SrTi0.95Nb0.05O3 , respectively, which are the highest values reported for rare earth doped SrTiO3.

NbTaV-(Ti,W) refractory high-entropy alloys: Experiments and modeling

Energy Technology Data Exchange (ETDEWEB)

Yao, H.W. [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Qiao, J.W., E-mail: qiaojunwei@gmail.com [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Gao, M.C., E-mail: michael.gao@netl.doe.gov [National Energy Technology Laboratory, 1450 Queen Ave SW, Albany, OR 97321 (United States); AECOM, P.O. Box 1959, Albany, OR 97321 (United States); Hawk, J.A. [National Energy Technology Laboratory, 1450 Queen Ave SW, Albany, OR 97321 (United States); Ma, S.G. [Institute of Applied Mechanics and Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhou, H.F. [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Y. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

2016-09-30

This study reports the design and development of ductile and strong refractory single-phase high-entropy alloys (HEAs) for high temperature applications, based on NbTaV with addition of Ti and W. Assisted by CALPHAD modeling, a single body-centered cubic solid solution phase was experimentally confirmed in the as-cast ingots using X-ray diffraction and scanning electron microscopy. The observed elemental segregation in each alloy qualitatively agrees with CALPHAD prediction. The Vickers microhardnesses (and yield strengths) of the alloys are about 3 (and 3.5–4.4) times that those estimated from the rule of mixture. While NbTaTiVW shows an impressive yield strength of 1420 MPa with fracture strain of 20%, NbTaTiV exhibits exceptional compressive ductility at room temperature.

Highly Stable and Active Pt/Nb-TiO2 Carbon-Free Electrocatalyst for Proton Exchange Membrane Fuel Cells

Directory of Open Access Journals (Sweden)

Shuhui Sun

2012-01-01

Full Text Available The current materials used in proton exchange membrane fuel cells (PEMFCs are not sufficiently durable for commercial deployment. One of the major challenges lies in the development of an inexpensive, efficient, and highly durable and active electrocatalyst. Here a new type of carbon-free Pt/Nb-TiO2 electrocatalyst has been reported. Mesoporous Nb-TiO2 hollow spheres were synthesized by the sol-gel method using polystyrene (PS sphere templates. Pt nanoparticles (NPs were then deposited onto mesoporous Nb-TiO2 hollow spheres via a simple wet-chemical route in aqueous solution, without the need for surfactants or potentiostats. The growth densities of Pt NPs on Nb-TiO2 supports could be easily modulated by simply adjusting the experimental parameters. Electrochemical studies of Pt/Nb-TiO2 show much enhanced activity and stability than commercial E-TEK Pt/C catalyst. PtNP/Nb-TiO2 is a promising new cathode catalyst for PEMFC applications.

Microstructural Characterization of Melt Extracted High-Nb-Containing TiAl-Based Fiber

Directory of Open Access Journals (Sweden)

Shuzhi Zhang

2017-02-01

Full Text Available The microstructure of melt extracted Ti-44Al-8Nb-0.2W-0.2B-1.5Si fiber were investigated. When the rotation speed increased from 2000 to 2600 r/min, the appearance of the wire was uniform with no Rayleigh-wave default. The structure was mainly composed of fine α2 (α phase dendritic crystal and a second phase between dendrite arms and grain boundaries. The precipitated second phases were confirmed to be Ti5Si3 from the eutectic reaction L→Ti5Si3 + α and TiB. As the lower content of Si and higher cooling rate, a divorced eutectic microstructure was obtained. Segregation of Ti, Nb, B, Si, and Al occurred during rapid solidification.

Design and optimization of superconducting magnet system for energy storage application

International Nuclear Information System (INIS)

Bhunia, Uttam

2015-01-01

In view of developing superconducting magnetic energy storage system (SMES) technology that will mitigate voltage sag/dip in the utility line, VEC centre has taken up a leading role in the country. In the first phase a solenoid-type 0.6 MJ SMES system using cryo-stable NbTi superconductor has been designed, developed and tested successfully with resistive load to mitigate power line voltage dips. The cryogenic test results of 0.6 MJ SMES coil will be highlighted. Further, effort is underway to develop a 4.5 MJ/1 MW SMES system with toroidal coil configuration. The lecture will also cover the superconducting coil development for SMES application with special emphasis on design aspects and the optimization issue of the toroidal system using NbTi based Rutherford-type cable. (author)

Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

Science.gov (United States)

Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

2013-12-01

The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility. © 2013 Elsevier Ltd. All rights reserved.

Electrochemical corrosion and bioactivity of Ti-Nb-Sn-hydroxyapatite composites fabricated by pulse current activated sintering.

Science.gov (United States)

Xiaopeng, Wang; Fantao, Kong; Biqing, Han; Yuyong, Chen

2017-11-01

Ti-Nb-Sn-hydroxyapatite (HA) composites were prepared by mechanical alloying for different times (unmilled, 4, 8 and 12h), followed by pulse current activated sintering. The effects of the milling time on the electrochemical corrosion resistance and bioactivity of the sintered Ti-35Nb-2.5Sn-15HA composites were investigated. Potentiodynamic polarization test results indicated that the sintered Ti-35Nb-2.5Sn-15HA composites exhibited higher corrosion resistance with increasing milling time. The corrosion potential and current of the Ti-35Nb-2.5Sn-15HA composite sintered by 12h milled powders were - 0.261V and 0.18μA/cm 2 , respectively, and this sintered composite showed a stable and wide passivation region. The hemolysis rate of the sintered Ti-35Nb-2.5Sn-15HA composites reduced with increasing milling time and the lowest hemolytic rate of the composites was 0.87%. In addition, the in vitro cell culture results indicated that the composite sintered by 12h milled powders had good biocompatibility. These results indicate the significant potential of Ti-35Nb-2.5Sn/xHA composites for biomedical implant applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Nb dopant on the structural and optical properties of nanocrystalline TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Kaleji, Behzad Koozegar, E-mail: bkaleji@yahoo.com [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box:14115-143, Tehran (Iran, Islamic Republic of); Sarraf-Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box:14115-143, Tehran (Iran, Islamic Republic of); Fujishima, Akira [Photo-catalyst Group, Kanagawa Academy of Science and Technology, KSP East 412, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012 (Japan)

2012-01-16

Highlights: Black-Right-Pointing-Pointer We coated Nb-doped TiO{sub 2} films on glazed porcelain via sol-gel dip coating method. Black-Right-Pointing-Pointer We examined coatings by degradation of MB solution and optical light transmittance. Black-Right-Pointing-Pointer Coatings show enhanced photo-catalytic activity in 1 mol% Nb. Black-Right-Pointing-Pointer Nb doping inhibited the grain growth, and which are found to inhibit the anatase to rutile phase transformation. - Abstract: In this study, preparation of Nb-doped (0-20 mol% Nb) TiO{sub 2} dip-coated thin films on glazed porcelain substrates via sol-gel process has been investigated. The effects of Nb on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films was examined by atomic force microscope and X-ray photoelectron spectroscopy. XRD and Raman study showed that the Nb doping inhibited the grain growth. The photo-catalytic activity of the film was tested on degradation of methylene blue. Best photo-catalytic activity of Nb-doped TiO{sub 2} thin films were measured in the TiO{sub 2}-1 mol% Nb sample. The average optical transmittance of about 47% in the visible range and the band gap of films became wider with increasing Nb doping concentration. The Nb{sup 5+} dopant presented substitutional Ti{sup 4+} into TiO{sub 2} lattice.

Phase relations, crystal structure, and phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) in In_2O_3–Nb_2O_5–TiO_2 system

International Nuclear Information System (INIS)

Su, Liumei; Fan, Xing; Cai, Gemei; Liu, Huashan; Jin, Zhanpeng

2015-01-01

Phase relations, crystal structures, and phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) in In_2O_3–Nb_2O_5–TiO_2 ternary system were investigated for the first time. A number of samples with different compositions were prepared by a solid-state reaction method, and phase assembles were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe micro-analysis (EPMA). Five three-phase regions, ten two-phase regions, and six single-phase solid solutions were determined in this system. The solid solution of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) is composed of both ordered monoclinic wolframite-type structure (0 ≤ x < 0.35) and disordered orthorhombic α-PbO_2 type structure (0.35 < x < 0.45). Driving force for composition-driven phase transformation in In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) stems from the ordering of cations. The ever reported compound InNbTiO_6 with an orthorhombic α-PbO_2 type structure was amended to be a monoclinic wolframite-type structure. Present investigations will be useful for the whole ceramic community working with In_2O_3–Nb_2O_5–TiO_2 ternary system as well as for the development of functional materials. - Highlights: • Phase relations of In_2O_3–Nb_2O_5–TiO_2 ternary system were constructed. • Crystal structures of a novel solid solution In_1_−_xNb_1_−_xTi_2_xO_4 were determined. • Crystal structure of InNbTiO_6 was amended to be a wolframite-type structure. • Composition-driven phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 was investigated.

Elastic stiffnesses of an Nb-Ti/Cu-composite superconductive wire

Science.gov (United States)

Kim, Sudook; Ledbetter, Hassel; Ogi, Hirotsugu

2000-09-01

Elastic-stiffness coefficients were determined on a 1.4-mm-diameter wire consisting of superconducting Nb-Ti fibers in a copper matrix, with a polyvinyl-resin coating. The matrix contained 324 Nb-Ti fibers. An electromagnetic-acoustic-resonance method was used to obtain five independent elastic-stiffness coefficients assuming transverse-isotropic symmetry. From these we calculated Young moduli, bulk modulus, and principal Poisson ratios. As a check, we used a mechanical-impulse-excitation method to directly measure the Young modulus in the fiber direction. The three-phase composite wire showed a 10% anisotropy in the Young modulus.

Stress-assisted discontinuous precipitation during creep of Ti3Al-Nb alloys

International Nuclear Information System (INIS)

Rowe, R.G.; Hall, E.L.

1991-01-01

Stress-assisted discontinuous precipitation was observed during creep of Ti-25Al-12.5Nb at. pct and associated with microstructures in which large primary creep strains were observed earlier. It was found that a large shift between the equilibrium beta(0) (B2) phase composition at the heat treatment temperature and disordered beta (bcc) phase at the creep temperature provided a driving force for discontinuous precipitation of disordered beta phase. Applied stress accelerated the growth of discontinuous beta phase at grain boundaries perpendicular to the principal stress axis, but did not produce a significant shift in composition. The difference between beta and ordered beta phase boundaries in the Ti-Al-Nb system at 650 C and 1040 C suggests that discontinuous precipitation or related dissolution should occur in all Ti3Al-Nb alloys. 11 refs

Growth and surface characterization of TiNbZr thin films deposited by magnetron sputtering for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Tallarico, D.A. [Federal University of Sao Carlos, Materials Science and Engineering Graduation Program, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil); Gobbi, A.L. [Brazilian Nanotechnology National Laboratory, Rua Giuseppe Máximo Scolfaro 10.000, CEP 13083-100 Campinas, SP (Brazil); Paulin Filho, P.I. [Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil); Maia da Costa, M.E.H. [Pontifical Catholic University of Rio de Janeiro, Department of Physics, CEP 22451-900 Rio de Janeiro, RJ (Brazil); Nascente, P.A.P., E-mail: nascente@ufscar.br [Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, SP (Brazil)

2014-10-01

Low modulus of elasticity and the presence of non-toxic elements are important criteria for the development of materials for implant applications. Low modulus Ti alloys can be developed by designing β-Ti alloys containing non-toxic alloying elements such as Nb and Zr. Actually, most of the metallic implants are produced with stainless steel (SS) because it has adequate bulk properties to be used as biomaterials for orthopedic or dental implants and is less expensive than Ti and its alloys, but it is less biocompatible than them. The coating of this SS implants with Ti alloy thin films may be one alternative to improve the biomaterial properties at a relatively low cost. Sputtering is a physical deposition technique that allows the formation of nanostructured thin films. Nanostructured surfaces are interesting when it comes to the bone/implant interface due to the fact that both the surface and the bone have nanoscale particle sizes and similar mechanical properties. TiNbZr thin films were deposited on both Si(111) and stainless steel (SS) substrates. The TiNbZr/Si(111) film was used as a model system, while the TiNbZr/SS film might improve the biocompatibility and extend the life time of stainless steel implants. The morphology, chemical composition, Young's modulus, and hardness of the films were analyzed by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and nanoindentation. - Highlights: • TiNbZr thin films were deposited on Si(111) and stainless steel (SS). • Their Young's modulus differences are within 5.3% and hardness 1.7%. • TiNbZr/SS film chemical composition remained almost constant with depth. • TiNbZr films presented nanostructured grains and low roughness for substrates. • TiNbZr/SS film hardness was about 100% greater than the SS substrate hardness.

Growth and surface characterization of TiNbZr thin films deposited by magnetron sputtering for biomedical applications

International Nuclear Information System (INIS)

Tallarico, D.A.; Gobbi, A.L.; Paulin Filho, P.I.; Maia da Costa, M.E.H.; Nascente, P.A.P.

2014-01-01

Low modulus of elasticity and the presence of non-toxic elements are important criteria for the development of materials for implant applications. Low modulus Ti alloys can be developed by designing β-Ti alloys containing non-toxic alloying elements such as Nb and Zr. Actually, most of the metallic implants are produced with stainless steel (SS) because it has adequate bulk properties to be used as biomaterials for orthopedic or dental implants and is less expensive than Ti and its alloys, but it is less biocompatible than them. The coating of this SS implants with Ti alloy thin films may be one alternative to improve the biomaterial properties at a relatively low cost. Sputtering is a physical deposition technique that allows the formation of nanostructured thin films. Nanostructured surfaces are interesting when it comes to the bone/implant interface due to the fact that both the surface and the bone have nanoscale particle sizes and similar mechanical properties. TiNbZr thin films were deposited on both Si(111) and stainless steel (SS) substrates. The TiNbZr/Si(111) film was used as a model system, while the TiNbZr/SS film might improve the biocompatibility and extend the life time of stainless steel implants. The morphology, chemical composition, Young's modulus, and hardness of the films were analyzed by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and nanoindentation. - Highlights: • TiNbZr thin films were deposited on Si(111) and stainless steel (SS). • Their Young's modulus differences are within 5.3% and hardness 1.7%. • TiNbZr/SS film chemical composition remained almost constant with depth. • TiNbZr films presented nanostructured grains and low roughness for substrates. • TiNbZr/SS film hardness was about 100% greater than the SS substrate hardness

Further investigations of the upper critical field and the high field critical current density in Nb-Ti and its alloys

International Nuclear Information System (INIS)

Hawksworth, D.G.; Larbalestier, D.C.

1980-09-01

This paper reports further measurements of Hc 2 in the Nb-Ti-Ta and Nb-Ti-Hf systems. Whilst we find only small enhancements of approx. 0.3 Tesla in μ 0 Hc 2 (4.2 0 K) compared to binary Nb-Ti, at 2 0 K there is a wide composition range in the Nb-Ti-Ta system where μ 0 Hc 2 (2 0 K) exceeds 15 Tesla, reaching a maximum of 15.5 Tesla. This represents an enhancement of 1.3 Tesla over unalloyed Nb-Ti. By comparison alloys in the Nb-Ti-Hf system show a maximum enhancement in μ 0 Hc 2 (2 0 K) of only 0.3 Tesla. The reasons both for the enhancements in Hc 2 and for the differences in behavior shown by alloys containing Ta and Hf are briefly discussed. This paper also discusses common features in the behavior of the high field critical current density, J/sub c/, of four commercial Nb-Ti composites and upon the basis of this behavior predict the enhancements in high field J/sub c/ to be expected from using Nb-Ti-Ta and its alloys

Effect of quenching in the Ti-Nb-2%Al alloys structure; Efeito da tempera na estrutura das ligas Ti-Nb-2%Al

Energy Technology Data Exchange (ETDEWEB)

Santos, L.C.O.; Matlakhova, L.A.; Matlakhov, A.N.; Toledo, R. [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Centro de Ciencias e Tecnologia. Lab. de Materiais Avancados (LAMAV)], e-mail: lucascunhasantos@terra.com.br

2006-07-01

In the present work, the Ti-Nb-2%Al alloys, with the rate varied Nb from 15 to 40%, they were submitted to the quenched since 1000 deg C, in water, to verify the influence of Nb in the structure and phase composition. The alloys were obtained in a process of five coalitions in an oven to electric arch and, soon afterwards, wrought the hot and homogenized to 1200 deg C, for 10 hours. After the quenching and conventional metallographic preparation of the samples obliquely cut, the alloys were examined through the optic microscopic, diffraction of ray-X and Vickers hardness. The very defined correlation was shown between the niobium rate and the structure resulting from the quenched alloys. The phase martensitic was revealed in the alloy with 15% Nb, the phases martensitic and beta metastable in the alloys containing above 30% Nb and the phase beta in the alloys with 38% Nb and 40% Nb. the hardness of the phase martensitic increases with the increment of the niobium rate. (author)

Successful performances of the EU-AltTF sample, a large size Nb{sub 3}Sn cable-in-conduit conductor with rectangular geometry

Energy Technology Data Exchange (ETDEWEB)

Della Corte, A; Corato, V; Di Zenobio, A; Fiamozzi Zignani, C; Muzzi, L; Polli, G M; Reccia, L; Turtu, S [Associazione EURATOM-ENEA sulla Fusione, Via E Fermi 45, 00044 Frascati, Rome (Italy); Bruzzone, P [EPFL-CRPP, Fusion Technology, 5232 Villigen PSI (Switzerland); Salpietro, E [European Fusion Development Agreement, Close Support Unit, Boltzmannstrasse 2, 85748 Garching (Germany); Vostner, A, E-mail: antonio.dellacorte@enea.i [Fusion for Energy, c/ Josep Pla 2, Edificio B3, 08019 Barcelona (Spain)

2010-04-15

One of the design features which yet offers interesting margins for performance optimization of cable-in-conduit conductors (CICCs), is their geometry. For relatively small size Nb{sub 3}Sn CICCs, operating at high electromagnetic pressure, such as those for the EDIPO project, it has been experimentally shown that a design based on a rectangular layout with higher aspect ratio leads to the best performance, especially in terms of degradation with electromagnetic loads. To extend this analysis to larger size Nb{sub 3}Sn CICCs, we manufactured and tested, in the SULTAN facility, an ITER toroidal field (TF) cable, inserted into a thick stainless steel tube and then compacted to a high aspect ratio rectangular shape. Besides establishing a new record in Nb{sub 3}Sn CICC performances for ITER TF type cables, the very good test results confirmed that the conductor properties improve not only by lowering the void fraction and raising the cable twist pitch, as already shown during the ITER TFPRO and the EDIPO test campaigns, but also by the proper optimization of the conductor shape with respect to the electromagnetic force distribution. The sample manufacturing steps, along with the main test results, are presented here.

Thermal Conductance and High-Frequency Properties of Cryogenic Normal or Superconducting Semi-rigid Coaxial Cables in the Temperature Range of 1-8 K

Science.gov (United States)

Kushino, A.; Kasai, S.; Ukibe, M.; Ohkubo, M.

2018-04-01

In this study, the characteristics of thin semi-rigid cables composed of different conductors and with outer diameters ranging from 0.86 to 1.19 mm were investigated at low temperatures. The thermal conductance was measured between approximately 1 and 8 K, and the frequency dependence of the attenuation in the cables was obtained at 3 K. The electrical conductors used in the cables were alloys: beryllium copper, brass, stainless steel (SUS304), phosphor bronze, cupronickel (CuNi), and niobium-titanium (NbTi). The thermal conductance of a commercial miniature coaxial cable with braided wires forming the outer electrical conductor was also examined for reference. The measured thermal conductance was compared to published data and that generated from material libraries and databases. Among the measured cables using normal metals, the semi-rigid cable composed of SUS304 conductors and a polytetrafluoroethylene insulator showed the lowest thermal conductance. The transmission performance of the semi-rigid cables using SUS304 or CuNi was improved by plating the central conductors with a silver coating of approximately 3 μm thickness, and their thermal conductance with the plating increased by approximately one order of magnitude. The superconducting NbTi semi-rigid cable exhibited the lowest thermal conductance of all the cables considered in the present study along with very small attenuation up to above 5 GHz.

Porous Nb-Ti based alloy produced from plasma spheroidized powder

Directory of Open Access Journals (Sweden)

Qijun Li

Full Text Available Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20–110 μm. With the decrease of particle size, a transformation from typical dendrite solidification structure to fine cell microstructure occurs. The surface of the spheroidized powder is coated by a layer of oxides consisting mainly of TiO2 and Nb2O5. Probabilities of sinter-neck formation and particle coalescence increases with increasing sintering temperature. Porous skeleton with relatively homogeneous pore distribution and open pore channel is formed after vacuum sintering at 1700 °C, and the porosity is 32%. The sintering kinetic analysis indicates that grain boundary diffusion is the primary mass transport mechanism during sintering process. Keywords: Powder metallurgy, Nb-Ti based alloy, Porous material, Mechanical alloying, Plasma spheroidizing, Solidification microstructure

Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery.

Science.gov (United States)

Hynowska, A; Blanquer, A; Pellicer, E; Fornell, J; Suriñach, S; Baró, M D; Gebert, A; Calin, M; Eckert, J; Nogués, C; Ibáñez, E; Barrios, L; Sort, J

2015-11-01

The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic β-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility. © 2014 Wiley Periodicals, Inc.

Nb-TiO{sub 2}/polymer hybrid solar cells with photovoltaic response under inert atmosphere conditions

Energy Technology Data Exchange (ETDEWEB)

Lira-Cantu, Monica; Khoda Siddiki, Mahbube; Munoz-Rojas, David; Amade, Roger [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Gonzalez-Pech, Natalia I. [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Instituto Tecnologico y de Estudios Superiores de Monterrey (ITESM), Ave. Eugenio Garza Sada, 64640 Monterrey, N.L. (Mexico)

2010-07-15

Hybrid Solar Cells (HSC) applying Nb-TiO{sub 2} in direct contact with a conducting organic polymer, MEH-PPV, show higher stability than the bare TiO{sub 2}-based HSC when analyzed under inert atmosphere conditions. IPCE analyses revealed that inert atmospheres affect directly the semiconductor oxide in the first stages of the analyses but photovoltaic performance stabilizes after several hours. A 20 wt% Nb-doped TiO{sub 2} presented the highest stability and photovoltaic properties. The behavior has been attributed to the solubility limit of Nb within the TiO{sub 2} beyond 20 wt% doping level where the co-existence of NbO{sub 2} is observed. The HSCs were analyzed under controlled N{sub 2} atmosphere and 1000 W/m{sup 2} (AM 1.5) irradiation. (author)

Corrosion-Resistant Ti- xNb- xZr Alloys for Nitric Acid Applications in Spent Nuclear Fuel Reprocessing Plants

Science.gov (United States)

Manivasagam, Geetha; Anbarasan, V.; Kamachi Mudali, U.; Raj, Baldev

2011-09-01

This article reports the development, microstructure, and corrosion behavior of two new alloys such as Ti-4Nb-4Zr and Ti-2Nb-2Zr in boiling nitric acid environment. The corrosion test was carried out in the liquid, vapor, and condensate phases of 11.5 M nitric acid, and the potentiodynamic anodic polarization studies were performed at room temperature for both alloys. The samples subjected to three-phase corrosion testing were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX). As Ti-2Nb-2Zr alloy exhibited inferior corrosion behavior in comparison to Ti-4Nb-4Zr in all three phases, weldability and heat treatment studies were carried out only on Ti-4Nb-4Zr alloy. The weldability of the new alloy was evaluated using tungsten inert gas (TIG) welding processes, and the welded specimen was thereafter tested for its corrosion behavior in all three phases. The results of the present investigation revealed that the newly developed near alpha Ti-4Nb-4Zr alloy possessed superior corrosion resistance in all three phases and excellent weldability compared to conventional alloys used for nitric acid application in spent nuclear reprocessing plants. Further, the corrosion resistance of the beta heat-treated Ti-4Nb-4Zr alloy was superior when compared to the sample heat treated in the alpha + beta phase.

Mechanical Effects of the Non-Uniform Current Distribution on HTS Coils for Accelerators Wound with REBCO Roebel Cable

CERN Document Server

Murtomaeki, Jaako; Kirby, Glen; Rossi, Lucio; Ruuskanen, Janne; Stenvall, Antti; Murtomaeki, Jaako

2017-01-01

Future high-energy accelerators will need very high magnetic fields in the range of 20 T. The EuCARD-2 WP10 Future Magnets collaboration is aiming at testing HTS-based Roebel cables in an accelerator magnet. The demonstrator should produce around 17 T, when inserted into the 100 mm aperture of Feather-M2 13 T outsert magnet. HTS Roebel cables are assembled from meander shaped REBCO coated conductor tapes. In comparison with fair level of uniformity of current distribution in cables made out of round Nb-Ti or Nb$_{3}$Sn strands, current distribution within the coils wound from Roebel cables is highly non-homogeneous. It results in nonuniform electromagnetic force distribution over the cable that could damage the very thin REBCO superconducting layer. This paper focuses on the numerical models to describe the effect of the non-homogenous current distribution on stress distribution in the demonstrator magnet designed for the EuCARD-2 project. Preliminary results indicate that the impregnation bonding betweenthe...

Porous TiNb2O7 Nanospheres as ultra Long-life and High-power Anodes for Lithium-ion Batteries

International Nuclear Information System (INIS)

Cheng, Qiushi; Liang, Jianwen; Lin, Ning; Guo, Cong; Zhu, Yongchun; Qian, Yitai

2015-01-01

Graphical abstract: Due to the combinative merits of porosity and nanostructure, porous TiNb 2 O 7 nanospheres exhibit ultra long cyclic life and excellent rate performance for lithium ion batteries. - Highlights: • Porous TiNb 2 O 7 nanospheres have been fabricated with the assistance of block copolymer P123. • The as-prepared TiNb 2 O 7 anodes present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle. • The TiNb 2 O 7 anodes show good rate performance of 167 mA h/g at 50C. • The TiNb 2 O 7 materials maintain the morphology of nanospheres and the porous structure even after 10000 cycles. - Abstract: Porous TiNb 2 O 7 nanospheres comprised of nanoparticles have been synthesized with the assistance of block copolymer P123 (EO 20 PO 70 EO 20 ). Such porous TiNb 2 O 7 nanospheres, with diameter of 500 nm, exhibit a BET surface area of 23.4 m 2 /g and pore volume of 0.155 cm 3 /g. As the anodes for lithium-ion batteries, the TiNb 2 O 7 nanospheres present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle, and good rate performance of 167 mA h/g at 50 C. Furthermore, the TiNb 2 O 7 materials still maintain the morphology of nanospheres and the porous structure even after 10000 cycles

Characterization of the critical current and physical properties of superconducting epitaxial NbTiN sub-micron structures

Energy Technology Data Exchange (ETDEWEB)

Klimov, A., E-mail: aklimov@ite.waw.pl [Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw (Poland); Słysz, W.; Guziewicz, M. [Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warsaw (Poland); Kolkovsky, V.; Zaytseva, I.; Malinowski, A. [Institute of Physics Polish Academy of Science, Al. Lotników 32/46, 02-668 Warsaw (Poland)

2017-05-15

Highlights: • This manuscript presents investigation of the critical current dependence of Nb(Ti)N nanostructured superconducting single photon detectors (SNSPD) in function of temperature and applied magnetic field. • Presented results are complimentary and compared with the same data received for submicron-wide single bridge Nb(Ti)N structures. • Our data demonstrate significant influence of local constrictions on physical properties of our SNSPD detectors. - Abstract: Measurements of critical current in NbTiN as a function of applied magnetic field and temperature are reported for two samples: 700-nm-wide bridge and 100-nm-wide meander. In 700-nm-wide NbTiN bridge we pinpointed the limiting factors for the critical current density to be current-driven vortex de-pinning at low temperatures and thermally activated flux flow closer to the transition temperature. In 100-nm-wide NbTiN meander we found phase slips activation, accompanied by hotspots formation at all measured temperatures. These two types of structures demonstrate different dependence of the critical current on the applied magnetic field. Although our NbTiN meander structures has high de-pairing critical current densities ∼10{sup 7} A/cm{sup 2} at low temperatures, the real critical currents are smaller due to the presence of the local constrictions.

Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

Science.gov (United States)

Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

2012-09-01

Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Crack resistance behaviour of an intermetallic Ti-Al-Si-Nb alloy at room temperature

International Nuclear Information System (INIS)

Wittkowsky, B.U.; Pfuff, M.J.

1996-01-01

The room temperature crack growth behaviour of a Ti-Al-Si-Nb alloy consisting of the two intermetallic phases (Ti, Nb) 3 (Al, Si) and (Ti, Nb) 5 (Si, Al) 3 is investigated in the present paper. The material exhibits a heterogeneous disordered microstructure and fails in a brittle manner. Crack growth is associated with a pronounced crack resistance behaviour. For a sample of nominally identical specimens the R-curves scatter around a mean curve with a standard deviation which remains roughly constant as the crack grows. A natural extension of the bundle model introduced in a previous paper is used to simulate R-curves and their scatter is in reasonably good agreement with the experimental findings. (orig.)

Production of low oxygen contamination orthorhombic Ti-Al-Nb intermetallic foil

International Nuclear Information System (INIS)

Gill, S.C.; Peters, J.A.; Blatter, P.; Jaquet, J.C.; Morris, M.A.

1996-01-01

Aerospace industries continue the search for high performance materials, and recent years have seen rapid developments being made in the capabilities of Ti-Al based intermetallic alloys. Interest in these alloys is caused by their attractive combination of strength and density, but major drawbacks include brittleness at low temperature and sensitivity to interstitial contamination. Development of a relatively new class of alloys was stimulated in 1988 by the discovery of Banerjee et al. of a Ti-Al-Nb orthorhombic (O) phase based on the Ti 2 AlNb composition. Some important applications for these alloys require the use of foil ( 2 phase and leads to material embrittlement. ELIT (Extra Low Interstitial Transfer) pack-rolling, developed by Sulzer Innotec, offers a technique to avoid oxygen contamination

Cos-$\\theta$ design of dipole inserts made of ReBCO-Roebel or BSCCO-Rutherford cables

CERN Document Server

Lorin, C; Fazilleau, P; Pes, C; Rifflet, J M; Segreti, M; Ballarino, A; Bottura, L; Fleiter, J; Kirby, G; Rossi, L; Van Nugteren, J

2015-01-01

Next generation of dipole magnets with field higher than 16 T are considered for future particle colliders. To do so, combined-technology magnets - made of Nb-Ti, Nb$_{3}$Sn and HTS materials - have to be developed to reduce the cost of such a magnet. Therefore, in the framework of the EuCARD-2 project, many HTS dipole magnet designs have to be investigated so as to find the most effective design for the HTS insert in a graded magnet. This paper discusses the Cosθ option. A 5 T standalone configuration of the HTS accelerator magnet (the first goal of EuCARD2) appears to be achievable, whereas mechanical stress distribution shows that its use as insert in graded magnet is very challenging. This paves the way for alternative designs as the so-called slot or motor-like design, briefly introduced here.

Experimental characterization of resistive joints for use inside ATLAS toroids

CERN Document Server

Volpini, G; Pojer, M

2001-01-01

The authors have investigated, both experimentally and theoretically, the thermo-electrical behavior of the ATLAS magnets resistive joints. These magnets exploit an Al-clad NbTi Rutherford superconducting cable, and the splices between different sections are performed by TIG-welding the Al matrices of the two cables to be connected. This technique is simple from a construction point of view, and we have shown that its performance is adequate for a safe operation of the magnets. The two main concerns during the design of these joints are the temperature rise due to Joule dissipation and the eddy currents induced under nonstationary conditions. We have devised a reliable model of these joints, that allows estimating their resistances and the induced eddy currents; later we have built and measured several sample joints to give experimental confirmation. The model requires, along with the joint geometry, the knowledge of the Rutherford-matrix interface resistance as well as the RRR of the aluminum matrix. In this...

Phase stability and elastic properties of β Ti-Nb-X (X = Zr, Sn) alloys: an ab initio density functional study

Science.gov (United States)

K, Rajamallu; Niranjan, Manish K.; Ameyama, Kei; Dey, Suhash R.

2017-12-01

Alloying effects of Zr and Sn on β phase stability and elastic properties in Ti-Nb alloys are investigated within the framework of first-principles density functional theory. Our results suggest that the stability of β phase can be significantly enhanced by the addition of Zr and Sn in Ti-Nb alloys. The computed results indicate that Zr and Sn behave as strong β stabilizers in the Ti-Nb system. The elastic properties are found to be altered considerably by the addition of ternary alloying elements (Zr and Sn). The computed elastic moduli of Ti18.75 at%Nb6.25 at%Zr and Ti25 at%NbxZr compositions are found to be lower than that for Ti18.75 at%Nb6.25 at%Sn and Ti25 at%NbxSn system. The lowest value of ˜54 GPa is obtained for Ti25 at%Nb6.25 at%Zr composition. Furthermore, the directional Young’s modulus is found to be in the order of E 100 system.

Phase transformation and microstructure evolution of the deformed Ti-30Zr-5Nb shape memory alloy

Energy Technology Data Exchange (ETDEWEB)

Qu, Wentao, E-mail: wtqu@xsyu.edu.cn [School of Mechanical Engineering, Xi' an Shiyou University, Xi' an 710065 (China); Sun, Xuguang; Yuan, Bifei [School of Mechanical Engineering, Xi' an Shiyou University, Xi' an 710065 (China); Xiong, Chengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Nie, Yongsheng [Lanzhou Seemine SMA Co. Ltd., Lanzhou 730010 (China)

2017-04-15

The phase transformation and microstructures of the deformed Ti-30Zr-5Nb shape memory alloy were investigated. The X-ray diffraction measurements indicated that the Ti-30Zr-5Nb alloy was composed of a single orthorhombic α″-martensite phase. The alloy exhibited one yielding behavior in the tensile test, with a critical stress of ~ 600 MPa and a tensile strain of approximately 15%. A shape memory recovery accompanied by a permanent strain was exhibited in the deformed alloys when heated at 873 K. The permanent strain increased with increasing pre-strain. The microstructure evolution of the deformed alloy was investigated by transmission electron microscopy. The results showed that the martensite reorientation occurred and the dislocations were generated during deformation. The alloy displayed a reversible martensite transformation start temperature as high as 763 K. However, no strain-induced martensite stabilization was found in the deformed alloy with different pre-strain levels, potentially because the large chemical energy of the Ti-30Zr-5Nb alloy depressed the effects of the elastic energy and the dissipative energy. - Highlights: • Ti-30Zr-5Nb alloy is composed of single orthorhombic α″-martensite phase with M{sub s} of 721 K. • No martensite stabilization has been found in Ti-30Zr-5Nb alloy with different pre-strain. • Ti-30Zr-5Nb shows the maximum shape memory effect of 2.75% with a pre-strain of 8%.

Comparisons of internal self-field magnetic flux densities between recent Nb{sub 3}Sn fusion magnet CICC cable designs

Energy Technology Data Exchange (ETDEWEB)

Kwon, S. P. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2016-09-15

The Cable-In-Conduit-Conductor (CICC) for the ITER tokamak Central Solenoid (CS) has undergone design change since the first prototype conductor sample was tested in 2010. After tests showed that the performance of initial conductor samples degraded rapidly without stabilization, an alternate design with shorter sub-cable twist pitches was tested and discovered to satisfy performance requirements, namely that the minimum current sharing temperature (Tcs) remained above a given limit under DC bias. With consistent successful performance of ITER CS conductor CICC samples using the alternate design, an attempt is made here to revisit the internal electromagnetic properties of the CICC cable design to identify any correlation with conductor performance. Results of this study suggest that there may be a simple link between the Nb3Sn CICC internal self-field and its Tcs performance. The study also suggests that an optimization process should exist that can further improve the performance of Nb3Sn based CICC.

First-principles predictions of structural, mechanical and electronic properties of βTiNb under high pressure

Science.gov (United States)

Wang, Z. P.; Fang, Q. H.; Li, J.; Liu, B.

2018-04-01

Structural, mechanical and electronic properties of βTiNb alloy under high pressure have been investigated based on the density functional theory (DFT). The dependences of dimensionless volume ratio, elastic constants, bulk modulus, Young's modulus, shear modulus, ductile/brittle, anisotropy and Poisson's ratio on applied pressure are all calculated successfully. The results reveal that βTiNb alloy is mechanically stable under pressure below 23.45 GPa, and the pressure-induced phase transformation could occur beyond this critical value. Meanwhile, the applied pressure can effectively promote the mechanical properties of βTiNb alloy, including the resistances to volume change, elastic deformation and shear deformation, as well as the material ductility and metallicity. Furthermore, the calculated electronic structures testify that βTiNb alloy performs the metallicity and the higher pressure reduces the structural stability of unit cell.

PLD prepared bioactive BaTiO.sub.3./sub. films on TiNb implants

Czech Academy of Sciences Publication Activity Database

Jelínek, Miroslav; Vaněk, Přemysl; Tolde, Z.; Buixaderas, Elena; Kocourek, Tomáš; Studnička, Václav; Drahokoupil, Jan; Petzelt, Jan; Remsa, Jan; Tyunina, Marina

2017-01-01

Roč. 70, Jan (2017), s. 334-339 ISSN 0928-4931 R&D Projects: GA ČR(CZ) GA15-05864S; GA ČR(CZ) GA15-01558S Institutional support: RVO:68378271 Keywords : BaTiO 3 * thin films * pld * implants * TiNb * ferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

Phase equilibria and crystal chemistry in the ternary system BaO-TiO 2-Nb 2O 5. II. New barium polytitanates with <5 mole% Nb 2O 5

Science.gov (United States)

Roth, R. S.; Ettlinger, L. D.; Parker, H. S.

1987-06-01

Four new compounds were found in the BaO-TiO 2-Nb 2O 5 system, each containing orth ≈ 9.9A˚, b mon ≈ a orth ≈ 17A˚). Ba 14Ti 40Nb 2O 99 is a 20-layer orthorhombic phase, Cmc*, withc ≈ 46.86A˚. Ba 10Ti 28Nb 2O 72 is a 7-layer monoclinic phase, C2m, c ≈ 16.72A˚, β ≈ 101.2°. Ba 18Ti 54Nb 2O 132 is a 13-layer monoclinic phase, C2m, c ≈ 30.65A˚, β ≈ 96°. The compositions were derived by analogy to the layers in Ba 4Ti 13 O 30 and Ba 6Ti 17O 40 and are consistent with limited phase equilibria data.

Is magnetic pinning a dominant mechanism in Nb-Ti

International Nuclear Information System (INIS)

Cooley, L.D.; Lee, P.J.; Larbalestier, D.C.

1991-01-01

In this paper, the authors compare the pinning behavior of an artificial pinning center (APC) composite and a nanometer-filament Nb 46.5 wt% Ti composite to that of a conventional Nb 48 wt% Ti composite. The microstructure of the APC composite resembles the conventional composite, where ribbons of normal metal form the pinning centers, whereas the nanometer-filament composite has no internal normal metal but pins instead at the filament surface. The APC composite exhibits much stronger pinning relative to B c 2 than the conventional composite (21.4 GN/m 3 , 7 T vs. 18.9 GN/m 3 , 11 T), which is possibly due to the increased amount of pinning center (50 vol.% vs. 25 vol.%), however the proximity effect reduces the B c 2 unfavorably

A novel layered titanoniobate LiTiNbO5: topotactic synthesis and electrochemistry versus lithium.

Science.gov (United States)

Colin, J-F; Pralong, V; Caignaert, V; Hervieu, M; Raveau, B

2006-09-04

A new layered titanoniobate, LiTiNbO5, an n = 2 member of the A(x)M(2n)O(4n+2) family, has been synthesized using a molten salt reaction between HTiNbO5 and an eutectic "LiOH/LiNO3". This compound crystallizes in the P2(1)/m space group with a = 6.41 A, b = 3.77 A, c = 8.08 A, and beta = 92 degrees . It exhibits |TiNbO5|(infinity) layers similar to HTiNbO5, but differs from the latter by a "parallel configuration" of its |TiNbO6|(infinity) ribbons between the two successive layers. The topotactic character of the reaction suggests that exfoliation plays a prominent role in the synthesis of this new form. This new phase intercalates reversibly 0.8 lithium through a first-order transformation leading to a capacity of 94 mAh/g at a potential of 1.67 V vs Li/Li+.

Inter-filament resistance, effective transverse resistivity and coupling loss in superconducting multifilamentary NbTi and Nb3Sn strands

NARCIS (Netherlands)

Zhou, Chao; Dhalle, Marc M.J.; Nijhuis, Arend

2012-01-01

The effective transverse resistivity of a range of multi-filamentary Nb3Sn and NbTi strands is measured with a direct four-probe method and the data are compared to the transverse resistivity values obtained from AC coupling loss experiments. Correspondence between both is satisfactory provided that

Ammonia Synthesis using Ti and Nb Nitride Nano-particles Prepared by Mesoporous Graphitic C3N4

KAUST Repository

Kumagai, Hiromu

2015-01-22

TiN and NbN nanoparticles were synthesized from mesoporous graphitic C3N4 (mpg-C3N4) as a reactive template and used as the catalyst for ammonia synthesis. The obtained TiN and NbN nanoparticles possess high surface areas of 299 and 275 m2 g-1, respectively, making them attractive in the use of catalysis and support. Although most of the TiN and NbN particles show no measurable activity for ammonia formation, the nanoparticles enabled an ammonia synthesis rate of 31 μmol h-1 g-cat-1 at 673 K and 0.1 MPa of synthesis gas (N2 + 3H2) for both TiN and NbN catalysts. It is evident that the formation of nanoparticles with high nitride surface area is essential for the materials to function as catalysts in ammonia synthesis. The addition of Fe to TiN enhanced the ammonia synthesis activity, whereas it had detrimental effects on the catalytic activity of NbN. The properties of these catalysts in ammonia synthesis are discussed.

Transverse load optimization in Nb3Sn CICC design; influence of cabling, void fraction and strand stiffness

International Nuclear Information System (INIS)

Nijhuis, A; Ilyin, Y

2006-01-01

We have developed a model that describes the transverse load degradation in Nb 3 Sn CICCs, based on strand and cable properties, and that is capable of predicting how such degradation can be prevented. The Nb 3 Sn cable in conduit conductors (CICCs) for the International Thermonuclear Experimental Reactor (ITER) show a significant degradation in their performance with increasing electromagnetic load. Not only do the differences in the thermal contraction of the composite materials affect the critical current and temperature margin, but mostly electromagnetic forces cause significant transverse strand contact and bending strain in the Nb 3 Sn layers. Here, we present the model for transverse electro-magnetic load optimization (TEMLOP) and report the first results of computations for the ITER type of conductors, based on the measured properties of the internal tin strand used for the toroidal field model coil (TFMC). As input, the model uses data describing the behaviour of single strands under periodic bending and contact loads, measured with the TARSIS set-up, enabling a discrimination in performance reduction per specific load and strand type. The most important conclusion of the model computations is that the problem of the severe degradation of large CICCs can be drastically and straightforwardly improved by increasing the pitch length of subsequent cabling stages. It is the first time that an increase of the pitches has been proposed and no experimental data are available yet to confirm this beneficial outcome of the TEMLOP model. Larger pitch lengths will result in a more homogeneous distribution of the stresses and strains in the cable by significantly moderating the local peak stresses associated with the intermediate-length twist pitches. The twist pitch scheme of the present conductor layout turns out to be unfortunately close to a worst-case scenario. The model also makes clear that strand bending is the dominant mechanism causing degradation. The

FT-NMR of {sup 93}Nb in TiO{sub 2} single crystal

Energy Technology Data Exchange (ETDEWEB)

Sato, Kazunori; Akai, Hisazumi [Osaka Univ., Toyonaka (Japan). Faculty of Science; Takeda, Sadamu [and others

1997-03-01

We determined the electric field gradient (EFG) at the impurity Nb site in TiO{sub 2} experimentally. It was shown that the principal component and the asymmetry parameter differ significantly from those of the host Ti site in TiO{sub 2}. Ab initio calculations of the EFG`s by the KKR method with the super-cell reproduced this experimental results if Nb{sup 5+} ion is simulated by shifting {epsilon}{sub f}. It was shown that considering the charge state of impurities was indispensable in calculating the EFG`s at impurity sites. (J.P.N.)

Mesostructured niobium-doped titanium oxide-carbon (Nb-TiO2-C) composite as an anode for high-performance lithium-ion batteries

Science.gov (United States)

Hwang, Keebum; Sohn, Hiesang; Yoon, Songhun

2018-02-01

Mesostructured niobium (Nb)-doped TiO2-carbon (Nb-TiO2-C) composites are synthesized by a hydrothermal process for application as anode materials in Li-ion batteries. The composites have a hierarchical porous structure with the Nb-TiO2 nanoparticles homogenously distributed throughout the porous carbon matrix. The Nb content is controlled (0-10 wt%) to investigate its effect on the physico-chemical properties and electrochemical performance of the composite. While the crystalline/surface structure varied with the addition of Nb (d-spacing of TiO2: 0.34-0.36 nm), the morphology of the composite remained unaffected. The electrochemical performance (cycle stability and rate capability) of the Nb-TiO2-C composite anode with 1 wt% Nb doping improved significantly. First, a full cut-off potential (0-2.5 V vs. Li/Li+) of Nb-doped composite anode (1 wt%) provides a higher energy utilization than that of the un-doped TiO2-C anode. Second, Nb-TiO2-C composite anode (1 wt%) exhibits an excellent long-term cycle stability (100% capacity retention, 297 mAh/g at 0.5 C after 100 cycles and 221 mAh/g at 2 C after 500 cycles) and improved rate-capability (192 mAh/g at 5 C), respectively (1 C: 150 mA/g). The superior electrochemical performance of Nb-TiO2-C (1 wt%) could be attributed to the synergistic effect of improved electronic conductivity induced by optimal Nb doping (1 wt%) and lithium-ion penetration (high diffusion kinetics) through unique pore structures.

Carbothermic reduction behaviors of Ti-Nb-bearing Fe concentrate from Bayan Obo ore in China

Science.gov (United States)

Wang, Guang; Du, Ya-xing; Wang, Jing-song; Xue, Qing-guo

2018-01-01

To support the development of technology to utilize low-grade Ti-Nb-bearing Fe concentrate, the reduction of the concentrate by coal was systematically investigated in the present paper. A liquid phase formed when the Ti-Nb-bearing Fe concentrate/coal composite pellet was reduced at temperatures greater than 1100°C. The addition of CaCO3 improved the reduction rate when the slag basicity was less than 1.0 and inhibited the formation of the liquid phase. Mechanical milling obviously increased the metallization degree compared with that of the standard pellet when reduced under the same conditions. Evolution of the mineral phase composition and microstructure of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet at 1100°C were analyzed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectroscopy. The volume shrinkage value of the reduced Ti-Nb-bearing Fe concentrate/coal composite pellet with a basicity of 1.0 was approximately 35.2% when the pellet was reduced at 1100°C for 20 min, which enhanced the external heat transfer to the lower layers when reduced in a practical rotary hearth furnace. The present work provides key parameters and mechanism understanding for the development of carbothermic reduction technology of a Ti-Nb-bearing Fe concentrate incorporated in a pyrometallurgical utilization flow sheet.

Growth of a TiNb adhesion interlayer for bioactive coatings

Czech Academy of Sciences Publication Activity Database

Tolde, Z.; Starý, V.; Cvrček, L.; Vandrovcová, Marta; Remsa, J.; Daniš, S.; Krčil, J.; Bačáková, Lucie; Špatenka, P.

2017-01-01

Roč. 80, Nov 1 (2017), s. 652-658 ISSN 0928-4931 R&D Projects: GA ČR(CZ) GA15-01558S Institutional support: RVO:67985823 Keywords : biomaterials * PVD * TiNb * surface properties * BaTiO3 Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Biomaterials (as related to medical implants, devices, sensors) Impact factor: 4.164, year: 2016

Me-Si-C (Me= Nb, Ti or Zr) : Nanocomposite and Amorphous Thin Films

OpenAIRE

Tengstrand, Olof

2012-01-01

This thesis investigates thin films of the transition metal carbide systems Ti-Si-C, Nb-Si-C, and Zr-Si-C, deposited at a low substrate temperature (350 °C) with dc magnetron sputtering in an Ar discharge. Both the electrical and mechanical properties of these systems are highly affected by their structure. For Nb-Si-C, both the ternary Nb-Si-C and the binary Nb-C are studied. I show pure NbC films to consist of crystalline NbC grains embedded in a matrix of amorphous carbon. The best combina...

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, L.; Starch, W.; Lee, P.J.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J/sub c/) of Nb 45.6 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J/sub c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in the authors own laboratories without extrusion. Very high J/sub c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J/sub c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μ filament Nb-Ti composites

Limitation of critical current density by intermetallic formation in fine filament Nb-Ti superconductors

International Nuclear Information System (INIS)

Larbalestier, D.C.; Chengren, Li; Lee, P.J.; Starch, W.

1985-01-01

Two experiments have been performed to investigate the role that the intermetallic reaction between the copper matrix and the Nb-Ti filaments plays in limiting the critical current density (J /SUB c/ ) of Nb 46.5 wt% Ti composites. The first experiment involved composites which were industrially extruded. It was found that as the number of heat treatments increased, the J /SUB c/ declined, the resistive transition broadened and the filaments sausaged. The filament sausaging was initiated by intermetallic particles at the filament matrix interface. A series of many heat treatment procedures were then applied to composites fabricated in our own laboratories without extrusion. Very high J /SUB c/ values were obtained at filament sizes of 20 μm. When the same heat treatment procedures were applied to 4 - 5 μm conductors, extensive sausaging and degraded J /SUB c/ values resulted. This degradation was also found to be due to the formation of Cu-Nb-Ti intermetallic compounds. It is concluded that a reliable filament diffusion barrier technology is necessary to permit full flexibility in the heat treatment of 2 - 5 μm filament Nb-Ti composites

Effect of nitrogen addition and annealing temperature on superelastic properties of Ti-Nb-Zr-Ta alloys

Energy Technology Data Exchange (ETDEWEB)

Tahara, Masaki [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kim, Hee Young, E-mail: heeykim@ims.tsukuba.ac.jp [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Hosoda, Hideki [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Nam, Tae-hyun [School of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Miyazaki, Shuichi, E-mail: miyazaki@ims.tsukuba.ac.jp [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); School of Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processingnd ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2010-10-15

Research highlights: In this study, the effects of composition and annealing temperature on microstructure, shape memory effect and superelastic properties were investigated in Ti-Nb-4Zr-2Ta-N alloys by measuring stress-strain curves at various temperatures and using transmission electron microscopy. Dissolution of {alpha} phase increases M{sub s} and decreases the critical stress for slip for the Ti-22Nb-4Zr-2Ta alloy while it causes the decrease of M{sub s} and the increase of the critical stress for slip for the Ti-20Nb-4Zr-2Ta-0.6N alloy. The different effect of dissolution of {alpha} phase can be attributed to the fact that N is absorbed in {alpha} phase. - Abstract: The composition dependence of the mechanical properties and martensitic transformation behavior of Ti-Nb-4Zr-2Ta-N alloys is investigated. The effect of annealing temperature on the microstructural evolution and superelastic properties in the N-added and N-free alloys is compared. The addition of N decreases M{sub s} of Ti-Nb-4Zr-2Ta alloys by about 200 K per 1 at.%N and improves the superelastic properties of Ti-Nb-4Zr-2Ta alloys. The dissolution of {alpha} phase increases the martensitic transformation start temperature and decreases the superelastic recovery strain for the N-free alloy, whereas it causes opposite effects for the N-added alloy. The different annealing temperature dependences of superelastic properties are discussed on the basis of microstructure observation.

Effect of nitrogen addition and annealing temperature on superelastic properties of Ti-Nb-Zr-Ta alloys

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Hosoda, Hideki; Nam, Tae-hyun; Miyazaki, Shuichi

2010-01-01

Research highlights: In this study, the effects of composition and annealing temperature on microstructure, shape memory effect and superelastic properties were investigated in Ti-Nb-4Zr-2Ta-N alloys by measuring stress-strain curves at various temperatures and using transmission electron microscopy. Dissolution of α phase increases M s and decreases the critical stress for slip for the Ti-22Nb-4Zr-2Ta alloy while it causes the decrease of M s and the increase of the critical stress for slip for the Ti-20Nb-4Zr-2Ta-0.6N alloy. The different effect of dissolution of α phase can be attributed to the fact that N is absorbed in α phase. - Abstract: The composition dependence of the mechanical properties and martensitic transformation behavior of Ti-Nb-4Zr-2Ta-N alloys is investigated. The effect of annealing temperature on the microstructural evolution and superelastic properties in the N-added and N-free alloys is compared. The addition of N decreases M s of Ti-Nb-4Zr-2Ta alloys by about 200 K per 1 at.%N and improves the superelastic properties of Ti-Nb-4Zr-2Ta alloys. The dissolution of α phase increases the martensitic transformation start temperature and decreases the superelastic recovery strain for the N-free alloy, whereas it causes opposite effects for the N-added alloy. The different annealing temperature dependences of superelastic properties are discussed on the basis of microstructure observation.

A tri-junction diffusion couple analysis of the Nb-Cr-Ti system at 950{degrees}C

Energy Technology Data Exchange (ETDEWEB)

Thoma, D.J. [Los Alamos National Lab., NM (United States); Perepezko, J.H. [Wisconsin Univ., Madison, WI (United States). Dept. of Materials Science and Engineering

1993-11-01

With a three-way diffusion couple consisting of a tri-junction between three elements, a whole spectrum of phase development and ternary equilibria is available within a single isothermal sample. Binary equilibria (for the three binary systems) are also available in single sample by analyzing diffusion zones at composition limits outside the field of ternary interaction. The tri-junction approach was employed to evaluate ternary phase formation, ternary solubility limits of binary phases, and diffusion paths in a candidate high-temperature structural system (Nb-Cr-Ti). Ternary phase equilibria and tie lines have been defined at 950C and results confirmed with isothermal anneals of two-phase ternary alloys. The continuous solubility in TiCr{sub 2}-NbCr{sub 2} region is broadened by at least 5 at. % from binary intermetallic phase fields. No new ternary phases were detected in the Nb-CrTi system at 950C. By examining the relative shifts in the diffusion interfaces, a qualitative ranking of interdiffusion suggests that addition of Nb restricts diffusion of Cr into Ti compared to binary (Cr/Ti) behavior.

Tests of high gradient superconducting quadrupole magnets for the Tevatron

International Nuclear Information System (INIS)

Lamm, M.J.; Carson, J.; Gourlay, S.; Hanft, R.; Koepke, K.; Mantsch, P.; McInturff, A.D.; Riddiford, A.; Strait, J.

1989-09-01

Tests have been completed on three prototype magnets and two production magnets to be used for the Tevatron Dφ/Bφ low- β insertion. These cold iron, two shell quadrupoles are made of 36 strand Rutherford type NbTi superconducting cable. Magnet field gradients well in excess of the design 1.41 T/cm have been achieved at a transfer function of 0.291 T/cm/kA. Quench performance at 4.2 K and 3.7 K and magnetic multipole measurement data are presented and discussed. 9 refs., 4 figs., 4 tabs

Development and manufacture of ultra-fine NbTi filament wires at ALSTHOM

International Nuclear Information System (INIS)

Hoang, G.K.; Laumond, Y.; Sabrie, J.L.; Dubots, P.

1986-01-01

Ultra-fine NbTi filament wires have been developed and manufactured by ALSTHOM. It is now possible to produce industrial copper -copper-nickel matrix wires with 0.6 mu m NbTi filaments for use in 50 / 60 Hz machines. Smaller filaments with diameters down to 0.08 mu m have been obtained with 254 100 filament wire samples. Studies are now being carried out on copper matrix conductors to reduce the filament diameter. The first results show that it is possible to obtain submicron filaments even in copper matrix wires

The X-ray electronic spectra of TiC-NbC solid solution

International Nuclear Information System (INIS)

Cherkashenko, V.M.; Ezhov, A.V.; Nazarova, S.Z.; Kurmaev, Eh.Z.; Nojmann, M.

2001-01-01

X-ray photoelectronic spectra of inner levels and valency lands in TiC-NbC solid solutions were studied. Results of combining TiL α -, NbL β2.15 -, CK α - X-ray emission spectra and photoelectronic spectra of valency bands in one energy scale in reference to the Fermi level were analyzed. It is shown that a change in crystal lattice parameters, as well as charge redistribution between titanium and niobium atoms, produce a strong effect on electronic structure formation in the mixed carbides mentioned [ru

Influence of Nb content on the structural and optical properties of anatase TiO{sub 2} polycrystalline thin film by e-beam technique

Energy Technology Data Exchange (ETDEWEB)

Shah, A., E-mail: attaullah77@yahoo.com; Mahmood, Arshad; Aziz, Uzma; Rashid, Rashad; Raza, Qaiser; Ali, Zahid

2016-09-01

In this paper, we report the structural and optical properties of Nb-doped TiO{sub 2} thin films deposited by e-beam evaporation technique. After post annealing in air at 500 °C for 1 h, the samples were characterized by various techniques such as X-ray diffraction (XRD), Raman spectroscopy, UV–Vis spectrophotometry and spectroscopic Ellipsometer. Both XRD and Raman analyses indicate that the films were crystallized into the polycrystalline anatase TiO{sub 2} structure. However it was observed that the crystallinity of the films decreases with the addition of Nb atoms and tends to become amorphous at 20% Nb content in TiO{sub 2} film. Moreover, no new phases such as Nb{sub 2}O{sub 5}, NbO{sub 2} or Nb metal were observed. The band gap energy was found to decrease with the increasing of Nb concentration which was verified by ellipsometric study. Ellipsomtric measurements also indicate that refractive index (n) of the films decreases while extinction coefficient (k) increases with the increasing of Nb content. All these analyses elucidate that the incorporation of Nb atom into TiO{sub 2} may tune the structural and optical properties of TiO{sub 2} thin films. - Highlights: • The addition of Nb into TiO{sub 2} film has strongly influenced its physical properties. • Anatase polycrystalline Nb:TiO{sub 2} films were grown up to 15% Nb content. • The film becomes an amorphous at 20% Nb doping. • Band gap energy of TiO{sub 2} film was decreased with increasing of Nb content in the film. • The Optical constants (n, k) of Nb:TiO{sub 2} film were varied as a function of Nb content.

The characteristics of precipitates in 18% Cr/30% Ni cast steel with additions of Nb and Ti

International Nuclear Information System (INIS)

Piekarski, B.

1995-01-01

The microstructure of austenitic cast steel with approx. 0.3%C, 4.37%Si, 0.69%Mn, 17.8%Cr, 29.3%Ni, 1.47%Nb and 1.07%Ti have been examined after ageing at 900 C for 300 h. There was found five precipitates: M 23 C 6 , MnS, Ni 3 Fe, (Ti,Nb)C and an intermetallic Ni-Nb-S phase. Ni, Nb, Si-rich precipitate could have been formed in as cast condition. (author)

Magnetization and critical currents of NbTi wires with fine filaments

International Nuclear Information System (INIS)

Ghosh, A.K.; Sampson, W.B.

1985-01-01

In high energy accelerators such as the SSC, the magnetization of the superconductor is an important component in determining the harmonic fields at injection (approx.0.3T). In an effort to reduce these residual fields, interest has focused on NbTi conductors with fine filaments which are expected to have a reduced magnetization as dictated by the critical state model. With this in view, the magnetization and critical currents were measured at 4.3K for a set of NbTi wires with filament diameters, d, ranging from 1.0 to 5.0 microns. The data show that, although the magnetization scales linearly with d, it does not do so with the product J/sub c/d for d less than 3 μm. However, at these d values, the critical transport current density, J/sub c/ of NbTi was observed to decrease rapidly as a function of d. The origin of this J/sub c/ degradation and its effect on the scaling of magnetization within the framework of the critical state model is explored. We also examine the question of the observed asymmetry of the hysteretic magnetization

NbTi Strands Verification for ITER PF CICC Process Qualification of CNDA

Science.gov (United States)

Liu, F.; Liu, H.; Liu, S.; Liu, B.; Lei, L.; Wu, Y.

2014-05-01

China is in charge of most of Poloidal Field (PF) conductors production for the International Thermonuclear Experimental Reactor (ITER). The execution for PF conductors shall be in three main phases. According to ITER Procurement Arrangement (PA), the Domestic Agency (DA) shall be required to verify the room and low temperature acceptance tests carried out by the strand suppliers. As the reference laboratory of Chinese DA (CNDA), the superconducting strands test laboratory of Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) was undertaking the task of strands verification for ITER conductors. The verification test includes: diameter, Nickel plating thickness, copper-to-non-copper volume ratio, twist pitch direction and length, standard critical current (IC) and resistive transition index (n), residual resistance ration (RRR), and hysteresis loss. 48 NbTi strands with 7 billets were supplied for the PF Cable-In-Conduit Conductor (CICC) process qualification. In total, 54 samples were measured. The verification level for PF CICC process qualification was 100%. The test method, facility and results of each item are described in detail in this publication.

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

International Nuclear Information System (INIS)

Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

2016-01-01

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Shape memory and superelastic behavior of Ti-7.5Nb-4Mo-1Sn alloy

International Nuclear Information System (INIS)

Zhang, D.C.; Lin, J.G.; Jiang, W.J.; Ma, M.; Peng, Z.G.

2011-01-01

Research highlights: → A Ti-based shape memory alloy, Ti-7.5Nb-4Mo-1Sn, was designed. → The martensitic transformation start temperature of the alloy, M s , is 261 K. → The alloy exhibits good shape memory and superelastic behaviors. → The alloy also shows a good superelastic stability at room temperature. → The Ti-5Mo-7.5Nb-1Sn alloy has a potential application as a biomedical material. -- Abstract: In the present work, a Ti-based shape memory alloy with the composition of Ti-7.5Nb-4Mo-1Sn was designed based on the d-electron orbit theory. The shape memory and superelastic behavior of the alloy were investigated. It is found that the martensitic transformation temperature of the alloy is near 261 K. The tensile and the thermal cycling testing results show that the alloy exhibits the stable shape memory effect and superelasticity at room temperature. The maximum recovered strain of the alloy is 4.83%.

Ti2Nb10O29-x mesoporous microspheres as promising anode materials for high-performance lithium-ion batteries

Science.gov (United States)

Deng, Shengjue; Luo, Zhibin; Liu, Yating; Lou, Xiaoming; Lin, Chunfu; Yang, Chao; Zhao, Hua; Zheng, Peng; Sun, Zhongliang; Li, Jianbao; Wang, Ning; Wu, Hui

2017-09-01

Ti2Nb10O29 has recently been reported as a promising anode material for lithium-ion batteries. However, its poor electronic conductivity and insufficient Li+-ion diffusion coefficient significantly limit its rate capability. To tackle this issue, a strategy combining nanosizing and crystal-structure modification is employed. Ti2Nb10O29-x mesoporous microspheres with a sphere-size range of 0.5-4 μm are prepared by a one-step solvothermal method followed by thermal treatment in N2. These Ti2Nb10O29-x mesoporous microspheres exhibit primary nanoparticles, a large specific surface area (22.9 m2 g-1) and suitable pore sizes, leading to easy electron/Li+-ion transport and good interfacial reactivity. Ti2Nb10O29-x shows a defective shear ReO3 crystal structure with O2- vacancies and an increased unit cell volume, resulting in its increased Li+-ion diffusion coefficient. Besides Ti4+ and Nb5+ ions, Ti2Nb10O29-x comprises Nb4+ ions with unpaired 4d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti2Nb10O29-x mesoporous microspheres reveal superior electrochemical performances in term of large reversible specific capacity (309 mAh g-1 at 0.1 C), outstanding rate capability (235 mAh g-1 at 40 C) and durable cyclic stability (capacity retention of 92.1% over 100 cycles at 10 C).

Mechanical properties of heat treated and worn PVD, TiN, (Ti, Al)N, (Ti, Nb)N and Ti(C, N) coatings as measured by nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Vancoille, E.; Celis, J.P.; Roos, J.R. (Dept. of Metallurgy and Materials Engineering, Katholieke Univ. Leuven, Heverlee (Belgium))

1993-03-15

Steered arc ion plated TiN, (Ti[sub 50], Al[sub 50])N, (Ti[sub 85], Nb[sub 15])N and Ti(C[sub 60], N[sub 40]) coatings were heat treated in an inert argon atmosphere at temperatures up to 900degC. The hardness, Young's modulus and plasticity of the coatings were measured with nanoindentation after heating. As the coatings were annealed at higher temperatures, the hardness decreased and the plasticity increased. X-ray diffraction of the coatings showed that this corresponds to a decrease in internal stress and a change of crystallographic texture. The nanohardness of the cutting edge of coated drills was also measured after these were used in AISI 4140 steel. Scanning electron microscopy demonstrated the presence of a silicate layer located near the cutting edge of (Ti[sub 85], Nb[sub 15])N coated drills. Nanoindentation showed that the mechanical signature of the surface film further away from the cutting edge corresponded to a heat-treated coating covered with an oxide layer. (orig.).

Tribological behavior and self-healing functionality of TiNbCN-Ag coatings in wide temperature range

Energy Technology Data Exchange (ETDEWEB)

Bondarev, A.V., E-mail: abondarev88@gmail.com; Kiryukhantsev-Korneev, Ph.V.; Levashov, E.A.; Shtansky, D.V., E-mail: shtansky@shs.misis.ru

2017-02-28

Highlights: • TiNbCN–Ag coatings for wide temperature range tribological applications. • Alloying with Nb and Ag improve tribological properties and oxidation resistance. • Ag-rich TiNbCN coatings show friction coefficient below 0.45 in range of 25–700 °C. • Ag-doped coatings show active oxidation protection and self-healing functionality. - Abstract: Ag- and Nb-doped TiCN coatings with about 2 at.% of Nb and Ag contents varied between 4.0 and 15.1 at.% were designed as promising materials for tribological applications in a wide temperature range. We report on the structure, mechanical, and tribological properties of TiNbCN-Ag coatings fabricated by simultaneous co-sputtering of TiC{sub 0.5} + 10%Nb{sub 2}C and Ag targets in comparison with those of Ag-free coating. The tribological characteristics were evaluated during constant-temperature tests both at room temperature and 300 °C, as well as during dynamic temperature ramp tests in the range of 25–700 °C. The coating structure and elemental composition were studied by means of X-ray diffraction, scanning and transmission electron microscopy, and glow discharge optical emission spectroscopy. The coating microstructures and elemental compositions inside wear tracks, as well as the wear products, were examined by scanning electron microscopy, energy-dispersive spectroscopy, and Raman spectroscopy. We demonstrate that simultaneous alloying with Nb and Ag permits to overcome the main drawbacks of TiCN coatings such as their relatively high values of friction coefficient at elevated temperatures and low oxidation resistance. It is shown that a relatively high amount of Ag (15 at.%) is required to provide enhanced tribological behavior in a wide temperature range of 25–700 °C. In addition, the prepared Ag-doped coatings demonstrated active oxidation protection and self-healing functionality due to the segregation of Ag metallic particles in damage areas such as cracks, pin-holes, or oxidation sites.

Phase diagrams for pseudo-binary carbide systems TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC and HfC-TaC

International Nuclear Information System (INIS)

Gusev, A.I.

1985-01-01

Parameters of interaction and energy of mutual exchange in the liquid and solid phases of pseudobinary TiC-NbC, TiC-TaC, ZrC-NbC, ZrC-TaC, HfC-TaC systems are calculated with account of dependence on composition and temperature. Positions of liquidus-solidus phase boundaries on the phase diagrams of the mentioned systems are calculated on the basis of the determined mutual exchange energies in approximati.on of subregular solutions. The existance of latent decomposition ranges in the solid phase on the phase diagrams of the investgated systems is established

Oxidation behavior of U-2wt%Nb, Ti, and Ni alloys in air

International Nuclear Information System (INIS)

Ju, J. S.; Yoo, K. S.; Jo, I. J.; Gug, D. H.; Su, H. S.; Lee, E. P.; Bang, K. S.; Kim, H. D.

2003-01-01

For the long term storage safety study of the metallic spent fuel, U-Nb, U-Ti, U-Ni, U-Zr, and U-Hf simulated metallic uranium alloys, known as corrosion resistant alloys, were fabricated and oxidized in oxygen gas at 200 .deg. C-300 .deg. C. Simulated metallic uranium alloys were more corrosion resistant than pure uranium metal, and corrosion resistance increases Nb, Ni, Ti in that order. The oxidation rates of uranium alloys determined and activation energy was calculated for each alloy. The matrix microstructure of the test specimens were analyzed using OM, SEM, and EPMA. It was concluded that Nb was the best acceptable alloying elements for reducing corrosion of uranium metal considered to suitable as candidate

Surface modification by electrolytic plasma processing for high Nb-TiAl alloys

Science.gov (United States)

Gui, Wanyuan; Hao, Guojian; Liang, Yongfeng; Li, Feng; Liu, Xiao; Lin, Junpin

2016-12-01

Metal surface modification by electrolytic plasma processing (EPP) is an innovative treatment widely commonly applied to material processing and pretreatment process of coating and galvanization. EPP involves complex processes and a great deal of parameters, such as preset voltage, current, solution temperature and processing time. Several characterization methods are presented in this paper for evaluating the micro-structure surfaces of Ti45Al8Nb alloys: SEM, EDS, XRD and 3D topography. The results showed that the oxide scale and other contaminants on the surface of Ti45Al8Nb alloys can be effectively removed via EPP. The typical micro-crater structure of the surface of Ti45Al8Nb alloys were observed by 3D topography after EPP to find that the mean diameter of the surface structure and roughness value can be effectively controlled by altering the processing parameters. The mechanical properties of the surface according to nanomechanical probe testing exhibited slight decrease in microhardness and elastic modulus after EPP, but a dramatic increase in surface roughness, which is beneficial for further processing or coating.

Colossal Dielectric Behavior of Ga+Nb Co-Doped Rutile TiO2.

Science.gov (United States)

Dong, Wen; Hu, Wanbiao; Berlie, Adam; Lau, Kenny; Chen, Hua; Withers, Ray L; Liu, Yun

2015-11-18

Stimulated by the excellent colossal permittivity (CP) behavior achieved in In+Nb co-doped rutile TiO2, in this work we investigate the CP behavior of Ga and Nb co-doped rutile TiO2, i.e., (Ga(0.5)Nb(0.5))(x)Ti(1-x)O2, where Ga(3+) is from the same group as In(3+) but with a much smaller ionic radius. Colossal permittivity of up to 10(4)-10(5) with an acceptably low dielectric loss (tan δ = 0.05-0.1) over broad frequency/temperature ranges is obtained at x = 0.5% after systematic synthesis optimizations. Systematic structural, defect, and dielectric characterizations suggest that multiple polarization mechanisms exist in this system: defect dipoles at low temperature (∼10-40 K), polaronlike electron hopping/transport at higher temperatures, and a surface barrier layer capacitor effect. Together these mechanisms contribute to the overall dielectric properties, especially apparent observed CP. We believe that this work provides comprehensive guidance for the design of new CP materials.

TiZrNbTaMo high-entropy alloy designed for orthopedic implants: As-cast microstructure and mechanical properties.

Science.gov (United States)

Wang, Shao-Ping; Xu, Jian

2017-04-01

Combining the high-entropy alloy (HEA) concept with property requirement for orthopedic implants, we designed a Ti 20 Zr 20 Nb 20 Ta 20 Mo 20 equiatomic HEA. The arc-melted microstructures, compressive properties and potentiodynamic polarization behavior in phosphate buffer solution (PBS) were studied in detail. It was revealed that the as-cast TiZrNbTaMo HEA consisted of dual phases with bcc structure, major bcc1 and minor bcc2 phases with the lattice parameters of 0.3310nm and 0.3379nm, respectively. As confirmed by nanoindentation tests, the bcc1 phase is somewhat harder and stiffer than the bcc2 phase. The TiZrNbTaMo HEA exhibited Young's modulus of 153GPa, Vickers microhardness of 4.9GPa, compressive yield strength of σ y =1390MPa and apparent plastic strain of ε p ≈6% prior to failure. Moreover, the TiZrNbTaMo HEA manifested excellent corrosion resistance in PBS, comparable to the Ti6Al4V alloy, and pitting resistance remarkably superior to the 316L SS and CoCrMo alloys. These preliminary advantages of the TiZrNbTaMo HEA over the current orthopedic implant metals in mechanical properties and corrosion resistance offer an opportunity to explore new orthopedic-implant alloys based on the TiZrNbTaMo concentrated composition. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of microstructure and irradiation behavior of W–Nb/Ti composites prepared by spark plasma sintering

International Nuclear Information System (INIS)

Chen, Jing-Bo; Luo, Lai-Ma; Zhao, Mei-Ling; Xu, Qiu; Zan, Xiang; Wu, Yu-Cheng

2016-01-01

W–Nb/Ti composites were prepared by machine milling and spark plasma sintering. Field–emission scanning electron microscopy, high–resolution transmission electron microscopy, and X-ray diffraction analyses were used to characterize the samples. Thermal desorption spectroscopy (TDS) was used to measure the deuterium retention after only deuterium irradiation. The deuterium retention in W–4wt%Ti–wt1%Nb was lower than that in pure W (D_2"+ flux ∼10"2"2 ions/(m"2 s), ion energy ∼5 keV), Nb and Ti will improve the deuterium irradiation resistance of tungsten composite. In addition, transgranular and intergranular fractures were observed on the surface of the W–4 wt% Ti–1 wt% Nb composite. A Ti_(_X_)W_(_1_−_X_) solid solution was formed during sintering. The maximum tensile strength (410.53 MPa) was detected in the W–4wt%Ti–1wt%Nb composite at 600 °C.

Alloy Design and Property Evaluation of Ti-Mo-Nb-Sn Alloy for ...

African Journals Online (AJOL)

Ti-Mo alloy containing Nb and Sn were arc melted and composition analyzed by EDX. The XRD analysis indicates that the crystal structure and mechanical properties are sensitive to Sn concentration. A combination of Sn and Nb elements in synergy hindered formation athermal w phase and significantly enhanced b phase ...

The Application of 40Ti-35Ni-25Nb Filler Foil in Brazing Commercially Pure Titanium

Directory of Open Access Journals (Sweden)

Shan-Bo Wang

2018-03-01

Full Text Available The clad ternary 40Ti-35Ni-25Nb (wt % foil has been applied in brazing commercially pure titanium (CP-Ti. The wavelength dispersive spectroscope (WDS was utilized for quantitative chemical analyses of various phases/structures, and electron back scattered diffraction (EBSD was used for crystallographic analyses in the brazed joint. The microstructure of brazed joint relies on the Nb and Ni distributions across the joint. For the β-Ti alloyed with high Nb and low Ni contents, the brazed zone (BZ, consisting of the stabilized β-Ti at room temperature. In contrast, eutectoid decomposition of the β-Ti into Ti2Ni and α-Ti is widely observed in the transition zone (TZ of the joint. Although average shear strengths of joints brazed at different temperatures are approximately the same level, their standard deviations decreased with increasing the brazing temperature. The presence of inherent brittle Ti2Ni intermetallics results in higher standard deviation in shear test. Because the Ni content is lowered in TZ at a higher brazing temperature, the amount of eutectoid is decreased in TZ. The fracture location is changed from TZ into BZ mixed with α and β-Ti.

Bactericidal activity of the Ti-13Nb-13Zr alloy against different species of bacteria related with implant infection.

Science.gov (United States)

Aguilera-Correa, John-Jairo; Conde, Ana; Arenas, Maria-Angeles; de-Damborenea, Juan-Jose; Marin, Miguel; Doadrio, Antonio L; Esteban, Jaime

2017-08-11

The Ti-6Al-4V alloy is one of the most commonly used in orthopedic surgery. Despite its advantages, there is an increasing need to use new titanium alloys with no toxic elements and improved biomechanical properties, such as Ti-13Nb-13Zr. Prosthetic joint infections (PJI) are mainly caused by Gram-positive bacteria; however, Gram-negative bacteria are a growing problem due to associated multidrug resistance. In this study, the bacterial adherence and viability on the Ti-13Nb-13Zr alloy have been compared to that of the Ti-6Al-4V alloy using 16 collection and clinical strains of bacterial species related to PJI: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. When compared with the Ti-6Al-4V alloy, bacterial adherence on the Ti-13Nb-13Zr alloy was significantly higher in most staphylococcal and P. aeruginosa strains and lower for E. coli strains. The proportion of live bacteria was significantly lower for both Gram-negative species on the Ti-13Nb-13Zr alloy than on the Ti-6Al-4V alloy pointing to some bactericidal effect of the Ti-13Nb-13Zr alloy. This bactericidal effect appears to be a consequence of the formation of hydroxyl radicals, since this effect is neutralized when dimethylsulfoxide was added to both the saline solution and water used to wash the stain. The antibacterial effect of the Ti-13Nb-13Zr alloy against Gram-negative bacteria is an interesting property useful for the prevention of PJI caused by these bacteria on this potential alternative to the Ti-6Al-4V alloy for orthopedic surgery.

Enhanced upper critical fields in binary Nb-Ti alloys

International Nuclear Information System (INIS)

Hariharan, Y.; Sastry, V.S.; Janawadkar, M.P.; Radhakrishnan, T.S.

1986-01-01

The authors report the enhancement of H/sub c2/ in quenched and suitably heat treated binary Nb-65 at % Ti alloys. The inherent metastability of the bcc β phase and its instability towards athermal ω are used to realise high values of normal state resistivity ε/sub n/. The consequences of this on the upper critical field have been experimentally determined by the measurement of dH/sub c2//dT at T/sub c/ and of T/sub c/. These together with our similar measurements on Nb-83 at % Ti alloy to which at 1 at % N was added (to retain it in the β phase) are analysed in terms of the existing theories for upper critical fields. It is shown that a peak in H/sub c2/(o) occurs at 17 - 18 T when ε/sub n/ has a value of approximately 100 μΩcm

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

Energy Technology Data Exchange (ETDEWEB)

Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: mirabbas@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2016-10-30

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Influence of cold deformation on martensite transformation and mechanical properties of Ti-Nb-Ta-Zr alloy

International Nuclear Information System (INIS)

Wang Liqiang; Lu Weijie; Qin Jining; Zhang Fan; Zhang Di

2009-01-01

Ti-35Nb-2Ta-3Zr alloy was fabricated by vacuum consumable arc melting furnace and hot pressing. Microstructure and phase transformation of solution-treated (ST) and cold-rolled (CR) plates of Ti-Nb-Ta-Zr alloy were observed. Different microstructure of strain-induced martensite transformation during cold deformation were investigated. With the increase of reduction of cold rolling, microstructure of α''-phase changed from acicular martensite to butterfly shaped martensite and showed variant crossed and cross-hatched when the reduction of cold rolling was over 60%. Mechanical properties and SEM images of the fracture surface indicated that the alloy fabricated by cold deformation showed favorable strength and plasticity. Owing to the excellent cold workability and biomedical safety of elements of Nb, Ta and Zr, Ti-Nb-Ta-Zr alloy contributed much to medical applications

Thermo-magnetic instabilities in Nb3Sn Superconducting Accelerator Magnets

International Nuclear Information System (INIS)

Bordini, Bernardo; Pisa U.

2006-01-01

The advance of High Energy Physics research using circulating accelerators strongly depends on increasing the magnetic bending field which accelerator magnets provide. To achieve high fields, the most powerful present-day accelerator magnets employ NbTi superconducting technology; however, with the start up of Large Hadron Collider (LHC) in 2007, NbTi magnets will have reached the maximum field allowed by the intrinsic properties of this superconductor. A further increase of the field strength necessarily requires a change in superconductor material; the best candidate is Nb 3 Sn. Several laboratories in the US and Europe are currently working on developing Nb 3 Sn accelerator magnets, and although these magnets have great potential, it is suspected that their performance may be fundamentally limited by conductor thermo-magnetic instabilities: an idea first proposed by the Fermilab High Field Magnet group early in 2003. This thesis presents a study of thermo-magnetic instability in high field Nb 3 Sn accelerator magnets. In this chapter the following topics are described: the role of superconducting magnets in High Energy Physics; the main characteristics of superconductors for accelerator magnets; typical measurements of current capability in superconducting strands; the properties of Nb 3 Sn; a description of the manufacturing process of Nb 3 Sn strands; superconducting cables; a typical layout of superconducting accelerator magnets; the current state of the art of Nb 3 Sn accelerator magnets; the High Field Magnet program at Fermilab; and the scope of the thesis

Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C

Science.gov (United States)

Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon

2018-04-01

In this paper, the Al/Cr coating was fabricated on the surface of Ti2AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2AlNb alloy with prolonged air exposure at 900 °C. Al2O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2O3. Besides, Cr2O3 was produced under Al2O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2AlNb alloy increases oxidation resistance.

Effects of Nb doping level on the electronic transport, photoelectric effect and magnetoresistance across La0.5Ca0.5MnO3/Nb:SrTiO3 junctions

Science.gov (United States)

Wang, J. F.; Jiang, Y. C.; Chen, M. G.; Gao, J.

2013-12-01

Heterojunctions composed of La0.5Ca0.5MnO3 and Nb doped SrTiO3 were fabricated, and the effects of the Nb doping level on their electronic transport, photoelectric effect, and magnetoresistance were investigated. A lower doping concentration of Nb led to better rectifying properties and higher open circuit voltages. The I-V curves for La0.5Ca0.5MnO3/0.7 wt. % Nb-SrTiO3 showed a negligible response to magnetic fields for all temperatures, whereas La0.5Ca0.5MnO3/0.05 wt. % Nb-SrTiO3 exhibited distinct magnetoresistance, which depended on both the bias voltage and temperature. These results are discussed with the assistance of conventional semiconductor theories.

Magnetization measurements on multifilamentary Nb3Sn and NbTi conductors

International Nuclear Information System (INIS)

Ghosh, A.K.; Robins, K.E.; Sampson, W.B.

1984-01-01

The effective filament size has been determined for a number of high current Nb 3 Sn multifilamentary composites. In most cases it is much larger than the nominal filament size. For the smallest filaments (approx. 1 micron) the effective size can be as much as a factor of forty times the nominal size. Samples made by the internal tin, bronze route, and jelly roll methods have been examined with filaments in the range one to ten microns. Rate dependent magnetization and flux jumping have been observed in some cases. NbTi composites ranging in filament size from nine to two hundred microns and with copper to super-conductor ratios between 1.6:1 and 7:1 have been examined in the same apparatus. Low field flux jumping was only observed in conductors with very large filaments and relatively little stabilizing copper. 9 references, 6 figures, 3 tables

Effect of ion plating TiN on the oxidation of sputtered NiCrAlY-coated Ti3Al-Nb in air at 850-950 C

International Nuclear Information System (INIS)

Rizzo, F.C.; Zeng, C.; Chinese Academy of Sciences, Shenyang; Wu, W.

1998-01-01

A single sputtered NiCrAlY coating and a complex coating of inner ion-plated TiN and outer sputtered NiCrAlY were prepared on the intermetallic compound Ti 3 Al-Nb. Their oxidation behavior was examined at 850, 900, and 950 C in air by thermal gravimetry combined with XRD, SEM, and EDAX. The results showed that Ti 3 Al-Nb followed approximately parabolic oxidation, forming an outer thin Al 2 O 3 -rich scale and an inner TiO 2 -rich layer doped with Nb at the three temperatures. The TiO 2 -rich layer doped with Nb dominated the oxidation reaction. The single NiCrAlY coating did not follow parabolic oxidation exactly at 850 and 950 C, but oxidized approximately in a parabolic manner, because the instantaneous parabolic constants changed slightly with time. Besides the Al 2 O 3 scale, TiO 2 formed from the coating surface at the coating-substrate interface. The deterioration of the coating accelerated with increasing temperature. The NiCrAlY-TiN coating showed two-stage parabolic oxidation at 850 and 900 C, and an approximate parabolic oxidation at 950 C. The TiN layer was effective as a barrier to inhibit coating-alloy interdiffusion

Synthesis and characterization of Ti-27.5Nb alloy made by CLAD® additive manufacturing process for biomedical applications

International Nuclear Information System (INIS)

Fischer, M.; Laheurte, P.; Acquier, P.; Joguet, D.; Peltier, L.; Petithory, T.; Anselme, K.; Mille, P.

2017-01-01

Biocompatible beta-titanium alloys such as Ti-27.5(at.%)Nb are good candidates for implantology and arthroplasty applications as their particular mechanical properties, including low Young's modulus, could significantly reduce the stress-shielding phenomenon usually occurring after surgery. The CLAD® process is a powder blown additive manufacturing process that allows the manufacture of patient specific (i.e. custom) implants. Thus, the use of Ti-27.5(at.%)Nb alloy formed by CLAD® process for biomedical applications as a mean to increase cytocompatibility and mechanical biocompatibility was investigated in this study. The microstructural properties of the CLAD-deposited alloy were studied with optical microscopy and electron back-scattered diffraction (EBSD) analysis. The conservation of the mechanical properties of the Ti-27.5Nb material after the transformation steps (ingot-powder atomisation-CLAD) were verified with tensile tests and appear to remain close to those of reference material. Cytocompatibility of the material and subsequent cell viability tests showed that no cytotoxic elements are released in the medium and that viable cells proliferated well. - Highlights: • Biomimetic implants can be provided from additive manufacturing with beta-titanium alloys. • We studied the properties of a Ti-Nb alloy elaborated with a laser deposition process. • TiNb alloy processed by LMD consists of only beta phase due to rapid cooling. • No preferential crystallographic texture is observed with EBSD analyses. • TiNb samples showed a combination of high strength and low Young's modulus.

Large room-temperature tunneling anisotropic magnetoresistance and electroresistance in single ferromagnet/Nb:SrTiO3 Schottky devices.

Science.gov (United States)

Kamerbeek, Alexander M; Ruiter, Roald; Banerjee, Tamalika

2018-01-22

There is a large effort in research and development to realize electronic devices capable of storing information in new ways - for instance devices which simultaneously exhibit electro and magnetoresistance. However it remains a challenge to create devices in which both effects coexist. In this work we show that the well-known electroresistance in noble metal-Nb:SrTiO 3 Schottky junctions can be augmented by a magnetoresistance effect in the same junction. This is realized by replacing the noble metal electrode with ferromagnetic Co. This magnetoresistance manifests as a room temperature tunneling anisotropic magnetoresistance (TAMR). The maximum room temperature TAMR (1.6%) is significantly larger and robuster with bias than observed earlier, not using Nb:SrTiO 3 . In a different set of devices, a thin amorphous AlO x interlayer inserted between Co and Nb:SrTiO 3 , reduces the TAMR by more than 2 orders of magnitude. This points to the importance of intimate contact between the Co and Nb:SrTiO 3 for the TAMR effect. This is explained by electric field enhanced spin-orbit coupling of the interfacial Co layer in contact with Nb:SrTiO 3 . We propose that the large TAMR likely has its origin in the 3d orbital derived conduction band and large relative permittivity of Nb:SrTiO 3 and discuss ways to further enhance the TAMR.

Synthesis and characterization of Ti-27.5Nb alloy made by CLAD® additive manufacturing process for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Fischer, M. [LEM3, Université de Lorraine, Ile du Saulcy, 57045 Metz (France); Laheurte, P., E-mail: pascal.laheurte@univ-lorraine.fr [LEM3, Université de Lorraine, Ile du Saulcy, 57045 Metz (France); Acquier, P. [IREPA Laser, Institut Carnot Mica, Parc d' Innovation, 67400 Illkirch (France); Joguet, D. [LERMPS, Université de Technologie de Belfort Montbéliard, Sevenans, 90010 Belfort (France); Peltier, L. [LEM3, Ecole Nationale Supérieure d' Arts et Métiers, 57078 Metz (France); Petithory, T.; Anselme, K. [IS2M, CNRS UMR7361, Université de Haute-Alsace, 68057 Mulhouse (France); Mille, P. [LGECO Institut National des Sciences Appliquées, 67000 Strasbourg (France)

2017-06-01

Biocompatible beta-titanium alloys such as Ti-27.5(at.%)Nb are good candidates for implantology and arthroplasty applications as their particular mechanical properties, including low Young's modulus, could significantly reduce the stress-shielding phenomenon usually occurring after surgery. The CLAD® process is a powder blown additive manufacturing process that allows the manufacture of patient specific (i.e. custom) implants. Thus, the use of Ti-27.5(at.%)Nb alloy formed by CLAD® process for biomedical applications as a mean to increase cytocompatibility and mechanical biocompatibility was investigated in this study. The microstructural properties of the CLAD-deposited alloy were studied with optical microscopy and electron back-scattered diffraction (EBSD) analysis. The conservation of the mechanical properties of the Ti-27.5Nb material after the transformation steps (ingot-powder atomisation-CLAD) were verified with tensile tests and appear to remain close to those of reference material. Cytocompatibility of the material and subsequent cell viability tests showed that no cytotoxic elements are released in the medium and that viable cells proliferated well. - Highlights: • Biomimetic implants can be provided from additive manufacturing with beta-titanium alloys. • We studied the properties of a Ti-Nb alloy elaborated with a laser deposition process. • TiNb alloy processed by LMD consists of only beta phase due to rapid cooling. • No preferential crystallographic texture is observed with EBSD analyses. • TiNb samples showed a combination of high strength and low Young's modulus.

Optical temperature sensing by upconversion luminescence of Er doped Bi5TiNbWO15ferroelectric materials

Directory of Open Access Journals (Sweden)

Hua Zou

2014-12-01

Full Text Available The Er3+ doped Bi5TiNbWO15 ceramics have been synthesized using conventional solid-state reaction techniques. The crystal structure, ferroelectric properties, UC emission properties and especially the temperature sensing behaviors were systematically studied. With increasing Er3+ content, the investigation of XRD pattern, the ferroelectric loop and the UC emission indicated that the Er3+ ions dopants preferentially substituted the A sites of Bi3TiNbO9 and then Bi2WO6. Based on fluorescence intensity ratio (FIR technique, the observed results implied the ceramics were promising candidates for temperature sensors in the temperature range of 175 K −550 K. More importantly, this study provided a contrast of temperature sensitivity between emission from the same part (Bi3TiNbO9 in bismuth layered-structure and emission from the different part (Bi3TiNbO9 and Bi2WO6 in bismuth layered-structure for the first time.

Martensitic transformations and the shape memory effect in Ti-Zr-Nb-Al high-temperature shape memory alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fei; Yu, Zhiguo; Xiong, Chengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Qu, Wentao; Yuan, Bifei [School of Mechanical Engineering, Xi’an Shiyou University, Xi’an 710065 (China); Wang, Zhenguo [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China)

2017-01-02

The microstructures, phase transformations, mechanical properties and shape memory effect of Ti-20Zr-10Nb-xAl (x=1, 2, 3, 4 at%) alloys were investigated. The X-ray diffraction results show that the alloys are composed of a single martensitic α″-phase and that the corresponding unit cell volume decreases with increasing Al content. The reverse martensitic transformation start temperature (A{sub s}) of the Ti-20Zr-10Nb-Al alloy is 534 K and decreases with increasing Al content. The addition of Al results in solid solution strengthening and grain refinement strengthening, thus improving the mechanical properties and the shape memory effect of the Ti-20Zr-10 Nb-xAl alloys. The Ti-20Zr-10Nb-3Al alloy shows the greatest shape memory strain (3.2%) and the largest tensile strain (17.6%) as well as a very high tensile strength (886 MPa).

A Comparative Study on Corrosion Behavior of Ti-35Nb-5Ta-7Zr Ti-6Al-4V and CP-Ti in 0.9 wt% NaCl

Energy Technology Data Exchange (ETDEWEB)

Saji, Viswanathan S.; Jeong, Yong Hoon; Choe, Han Cheol [Andong National University, Andong (Korea, Republic of)

2009-08-15

Recently, quaternary titanium alloys of the system Ti-Nb-Ta-Zr received considerable research considerable research interest as potential implant materials because of their excellent mechanical properties and biocompatibility. However, only few reported works were available on the corrosion behavior of such alloys. Hence, in the present work, electrochemical corrosion of Ti-35Nb-5Ta-7Zr alloy, which has been fabricated by are melting and heat treatment, was studied in 0.9 wt% NaCl at 37{+-}1 .deg. C, along with biomedical grade Ti-6Al-4V and CP-Ti. The phase and microstructure of the alloys were investigated employing XRD and SEM. The results of electrochemical studies indicated that the corrosion resistance of the quaternary alloy was inferior to that of Ti-6Al-4V and CP Ti.

Surface characterization of Zr/Ti/Nb tri-layered films deposited by magnetron sputtering on Si(111) and stainless steel substrates

Energy Technology Data Exchange (ETDEWEB)

Tallarico, Denise A.; Gobbi, Angelo L.; Filho, Pedro I. Paulin; Galtayries, Anouk; Nascente, Pedro A. P. [Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905, Sao Carlos, SP (Brazil); Brazilian Synchrotron Light Laboratory, Microfabrication Laboratory, Rua Giuseppe Maximo Scolfaro 10.000, CEP 13083-100, Campinas, SP (Brazil); Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905, Sao Carlos, SP (Brazil); Ecole Nationale Superieure de Chimie de Paris (Chimie ParisTech), Laboratoire de Physico-Chimie des Surfaces, UMR CNRS 7045, F-75231 Paris cedex 05 (France); Federal University of Sao Carlos, Department of Materials Engineering, Via Washington Luis km 235, CEP 13565-905, Sao Carlos, SP (Brazil)

2012-09-15

Among metallic materials, commercially pure titanium and titanium alloys are very often used as biomaterials for implants. Among these alloys, titanium-aluminum-vanadium alloy Ti-6 A-4 V is one of the most commonly used due to its excellent biocompatibility and ability to allow bone-implant integration. A new class of Ti alloys employs Zr for solid-solution hardening and Nb as {beta}-phase stabilizer. Metals such as Ti, Nb, and Zr-known as valve metals-usually have their surfaces covered by a thin oxide film that forms spontaneously in air. This oxide film constitutes a barrier between the metal and the medium. The Ti-Nb-Zr alloys have mechanical and corrosion resistance characteristics which make them suitable for use as implants. Tri-layered films of Ti-Nb-Zr were deposited on both Si(111) and stainless steel (SS) substrates using dc magnetron sputtering equipment, under an argon atmosphere according to the following methodology: a 100 nm thick layer of Nb was deposited on the substrate, followed by a 200 nm thick layer of Ti, and finally a 50 nm thick layer of Zr, on top of the multilayer stack. The morphology and chemical composition of the films were analyzed by atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). AFM images showed that the Zr/Ti/Nb tri-layer films presented nanostructured grains and low roughness. The ToF-SIMS depth profiles confirmed the formation of a three-layered film on Si(111) with well-defined and sharp interfaces between the layers, while the deposition on the stainless steel substrate caused slight intermixing at the different alloy/Nb, Nb/Ti and Ti/Zr interfaces, reflecting the greater roughness of the raw substrate. The XPS results for the Zr/Ti/Nb layers deposited on Si(111) and SS confirmed that the outermost layer consisted of Zr only, with a predominance of ZrO{sub 2}, as the metal layer is passivated in air. An oxidation treatment of 1000 Degree

Effect of Nb Addition to Ti-Bearing Super Martensitic Stainless Steel on Control of Austenite Grain Size and Strengthening

Science.gov (United States)

Ma, Xiaoping; Langelier, Brian; Gault, Baptiste; Subramanian, Sundaresa

2017-05-01

The role of Nb in normalized and tempered Ti-bearing 13Cr5Ni2Mo super martensitic stainless steel is investigated through in-depth characterization of the bimodal chemistry and size of Nb-rich precipitates/atomic clusters and Nb in solid solution. Transmission electron microscopy and atom probe tomography are used to analyze the samples and clarify precipitates/atom cluster interactions with dislocations and austenite grain boundaries. The effect of 0.1 wt pct Nb addition on the promotion of (Ti, Nb)N-Nb(C,N) composite precipitates, as well as the retention of Nb in solution after cooling to room temperature, are analyzed quantitatively. (Ti, Nb)N-Nb(C,N) composite precipitates with average diameters of approximately 24 ± 8 nm resulting from epitaxial growth of Nb(C,N) on pre-existing (Ti,Nb)N particles, with inter-particle spacing on the order of 205 ± 68 nm, are found to be associated with mean austenite grain size of 28 ± 10 µm in the sample normalized at 1323 K (1050 °C). The calculated Zener limiting austenite grain size of 38 ± 13 µm is in agreement with the experimentally observed austenite grain size distribution. 0.08 wt pct Nb is retained in the as-normalized condition, which is able to promote Nb(C, N) atomic clusters at dislocations during tempering at 873 K (600 °C) for 2 hours, and increases the yield strength by 160 MPa, which is predicted to be close to maximum increase in strengthening effect. Retention of solute Nb before tempering also leads to it preferentially combing with C and N to form Nb(C, N) atom clusters, which suppresses the occurrence of Cr- and Mo-rich carbides during tempering.

Metastable beta Ti-Nb-Mo alloys with improved corrosion resistance in saline solution

International Nuclear Information System (INIS)

Chelariu, R.; Bolat, G.; Izquierdo, J.; Mareci, D.; Gordin, D.M.; Gloriant, T.; Souto, R.M.

2014-01-01

Graphical abstract: - Highlights: • Microstructural and electrochemical characterization of metastable beta Ti-Nb-Mo alloys for biomedical implantation. • Corrosion resistance was established in 0.9 wt% NaCl saline solution at 25 °C using conventional and microelectrochemical techniques. • The materials spontaneously form passivating oxide films on their surface. • Surface films are stable for polarizations more positive than those encountered in the human body. • The addition of niobium to Ti12Mo enhances the capacitive characteristics of the passivating oxide layers. - Abstract: The present study explores the microstructural characteristics and electrochemical responses of four metastable beta Ti-Nb-Mo alloys for biomedical implantation. They were synthesized by the cold crucible levitation melting technique, and compositions were selected to keep the molybdenum equivalency close to 12 wt% Mo eq . For the sake of comparison, Ti12Mo was also investigated. Microstructural characterization reveals that all the alloys are β (body-centred cubic structure), and the surface is composed by β equiaxial grains with dimensions in the range of tens to hundreds μm. The corrosion resistance (potentiodynamic polarization and electrochemical impedance spectroscopy) of the alloys was determined in 0.9 wt% NaCl saline solution at 25 °C. The materials spontaneously form a passivating oxide film on their surface, and they are stable for polarizations up to +1.0 V SCE . No evidence of localized breakdown of the oxide layers is found for polarizations more positive than those encountered in the human body. The passive layers show dielectric characteristics, and the wide frequency ranges displaying capacitive characteristics occur for both higher niobium contents in the alloy and longer exposures to the saline solution. The insulating characteristics of the oxide-covered surfaces were investigated by scanning electrochemical microscopy operated in the feedback mode

Investigation of B2 and related phases in the Ti-Al-Nb ternary systems

International Nuclear Information System (INIS)

Bendersky, L.A.; Boettinger, W.J.

1989-01-01

Alloy compositions around Ti 2 AlNb were studied to establish phase equilibria and transformations during cooling from 1100 degrees C and 1400 degrees C. In addition to general results obtained on a wide range of compositions, which include evidence for a broad B2 phase field, transformation of BCC Ti 4 Al 3 Nb to a phase with an omega-type structure is reported. Detailed analysis indicates that this phase has the B8 2 structure after annealing at 700 degrees C

Comparative study on the corrosion behavior of Ti-Nb and TMA alloys for dental application in various artificial solutions

International Nuclear Information System (INIS)

Bai, Y.J.; Wang, Y.B.; Cheng, Y.; Deng, F.; Zheng, Y.F.; Wei, S.C.

2011-01-01

The corrosion behavior of Ti-Nb dental alloy in artificial saliva with and without the addition of lactic acid and sodium fluoride was investigated by electrochemical techniques, with the commercial Titanium-molybdenum alloy (TMA) as a comparison. The chemical composition, microstructure and constitutional phase were characterized via energy dispersive spectrometry, optical microscope and X-ray diffraction, meanwhile the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements were carried out to study the corrosion resistance of experimental alloys, with the corroded surface being further characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the corrosion behavior of Ti-Nb alloy was similar to those TMA alloy samples in both artificial and acidified saliva solutions, whereas statistical analysis of the electrochemical impedance spectroscopy and polarization parameters showed Ti-Nb alloy exhibited better corrosion resistance in fluoridated saliva and fluoridated acidified saliva. SEM observation indicated that TMA alloy corroded heavily than Ti-Nb alloy in fluoride containing saliva. XPS surface analysis suggested that Nb 2 O 5 played an important role in anti-corrosion from the attack of fluoride ion. Based on the above finding, Ti-Nb alloy is believed to be suitable for the usage in certain fluoride treated dental works with excellent corrosion resistance in fluoride-containing oral media.

Ti-24Nb-4Zr-8Sn Alloy Pedicle Screw Improves Internal Vertebral Fixation by Reducing Stress-Shielding Effects in a Porcine Model.

Science.gov (United States)

Qu, Yang; Zheng, Shuang; Dong, Rongpeng; Kang, Mingyang; Zhou, Haohan; Zhao, Dezhi; Zhao, Jianwu

2018-01-01

To ensure the biomechanical properties of Ti-24Nb-4Zr-8Sn, stress-shielding effects were compared between Ti-24Nb-4Zr-8Sn and Ti-6Al-4V fixation by using a porcine model. Twelve thoracolumbar spines (T12-L5) of 12-month-old male pigs were randomly divided into two groups: Ti-24Nb-4Zr-8Sn (EG, n = 6) and Ti-6Al-4V (RG, n = 6) fixation. Pedicle screw was fixed at the outer edge of L4-5 vertebral holes. Fourteen measuring points were selected on the front of transverse process and middle and posterior of L4-5 vertebra. Electronic universal testing machine was used to measure the strain resistance of measuring points after forward and backward flexion loading of 150 N. Meanwhile, stress resistance was compared between both groups. The strain and stress resistance of measurement points 1, 2, 5, 6, 9, and 10-14 in Ti-24Nb-4Zr-8Sn fixation was lower than that of Ti-6Al-4V fixation after forward and backward flexion loading ( P Ti-24Nb-4Zr-8Sn fixation than that of Ti-6Al-4V fixation ( P Ti-24Nb-4Zr-8Sn internal fixation were less than that of Ti-6Al-4V internal fixation. These results suggest that Ti-24Nb-4Zr-8Sn elastic fixation has more biomechanical goals than conventional Ti-6Al-4V internal fixation by reducing stress-shielding effects.

Fabrication of TiNb{sub 2}O{sub 7} thin film electrodes for Li-ion micro-batteries by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Daramalla, V. [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India); Penki, Tirupathi Rao; Munichandraiah, N. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengalore 560012 (India); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India)

2016-11-15

Graphical abstract: The TiNb{sub 2}O{sub 7} thin film electrodes as anode material in Li-ion rechargeable micro-batteries are successfully demonstrated. The pulsed laser deposited TiNb{sub 2}O{sub 7} thin film electrode delivers high discharge specific capacity of 143 μAh μm{sup −1} cm{sup −2} at 50 μA cm{sup −2} current density, with 92% coulombic efficiency. The thin films are very stable in crystal structure, with good fast reversible reaction at average Li-insertion voltage 1.65 V. - Highlights: • TiNb{sub 2}O{sub 7} thin films fabricated by pulsed laser deposition. • TiNb{sub 2}O{sub 7} as anode thin films demonstrated successfully. • High discharge specific capacity with 92% coulombic efficiency. • Excellent crystal stability and good reversible reaction. - Abstract: Pulsed laser deposited TiNb{sub 2}O{sub 7} thin films are demonstrated as anode materials in rechargeable Li-ion micro-batteries. The monoclinic and chemically pure TiNb{sub 2}O{sub 7} films in different morphologies were successfully deposited at 750 °C. The single phase formation was confirmed by grazing incident X-ray diffraction, micro-Raman spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The oxygen partial pressure during the deposition significantly influenced the properties of TiNb{sub 2}O{sub 7} films. The TiNb{sub 2}O{sub 7} thin films exhibited excellent stability with fast kinetics reversible reaction. The TiNb{sub 2}O{sub 7} films showed initial discharge specific capacity of 176, 143 μAh μm{sup −1} cm{sup −2} at 30, 50 μA cm{sup −2} current densities respectively with 92% coulombic efficiency in a non-aqueous electrolyte consisting of Li{sup +} ions. The high discharge specific capacity of TiNb{sub 2}O{sub 7} thin films may be attributed to nanometer grain size with high roughness which offers high surface area for Li-diffusion during charge and discharge

Performance-Microstructure Relations in Ni/CGO Infiltrated Nb-doped SrTiO3 SOFC Anodes

DEFF Research Database (Denmark)

Ramos, Tania; Bernuy-Lopez, Carlos; Reddy Sudireddy, Bhaskar

2012-01-01

Nb-doped SrTiO3 solid oxide fuel cell (SOFC) anodes, infiltrated with CGO/Ni, were investigated by electrochemical impedance spectroscopy (EIS) and high resolution microscopy techniques, upon varying production and testing parameters. The electrochemical analysis involved a combination of distrib......Nb-doped SrTiO3 solid oxide fuel cell (SOFC) anodes, infiltrated with CGO/Ni, were investigated by electrochemical impedance spectroscopy (EIS) and high resolution microscopy techniques, upon varying production and testing parameters. The electrochemical analysis involved a combination...... of distribution of relaxation times (DRT) and complex non-linear least squares (CNLS) fitting routine. These electrodes were studied as singlephase or as composites with 8YSZ. Sr0.94Ti0.9Nb0.1O3-δ/ 10 vol.% 8YSZ composite infiltrated electrodes were the best overall performers, with enhanced performance stability...

Quality analysis of superconducting wire and cable for SSC dipole magnets

International Nuclear Information System (INIS)

Pollock, D.A.

1992-01-01

This paper reports that a critical component of the SSC collider dipole magnets is superconducting cable. The uniformity and reliability requirements for the dipoles place stringent demands on the cable. These needs have been defined as various contract requirements in the material specifications for NbTi alloy, superconducting wire and cable. A supplied qualification program is being started by the SSCL with industry to establish reliable sources of superconductor cable. Key to this qualification program is the establishment by industry of detailed process methods and controls for wire and cable manufacture. To monitor conductor performance, a computer database is being developed by the SSCL Magnet Systems Division Quality Assurance Department. The database is part of a program for ensuring superconductor uniformity by focusing on the understanding and control of variation. A statistical and graphical summary of current data for key performance variables will be presented in light of the specification requirement for uniformity. Superconductor material characteristics to be addressed will include Wire Critical Current (I c ), Copper Ratio (Cu:SC), Wire Diameter, Wire Piece Length, and Cable Dimensional Control

Spectro-photometric determination of niobium in Nb-Ti alloy using in-situ separation of Ti by masking with H3PO4

International Nuclear Information System (INIS)

Ghosh, Prasun; Dutta, M.; Jat, J.R.; Reddy, G.B.; Balaji Rao, Y.; Subba Rao, Y.

2016-01-01

The present paper details a simple procedure for the determination of Nb content in Nb-Ti alloy. The method involves dissolution of alloy in mixture of HNO 3 and HF followed by fuming with H 2 SO 4 . Subsequently, solution is taken for UV-Vis Spectro-photometric measurement after addition of Conc. H 3 PO 4 and H 2 O 2 . Hydrogen peroxide is added as coloring agent. Hydrogen peroxide (H 2 O 2 ) is known to form yellow color peroxo complex with both Niobium and Titanium in sulfuric acid medium and thus Ti will interfere with Nb in absorbance measurement. In view of this practical difficulty, in-situ separation of Ti during measurement has been resorted by masking Ti using Conc. H 3 PO 4 . Standard synthetic sample solution of Nb-Ti was prepared having Niobium and titanium in the ratio of 60:40, 50:50 and 40:60. Quantitative measurement of Niobium was carried out by UV-Visible spectrophotometer at 365 nm. The interference of titanium is prominent from the obtained Niobium concentration. Different ratios of H 3 PO 4 and H 2 SO 4 tried to arrive at optimum ratio to eliminate titanium interference and results are as shown. Quantitative measurement of Niobium was carried out at 355 nm as absorption maxima shifted from 365 nm to 355 nm in presence of phosphoric acid. Results show a good agreement with synthetic standard at 80:20 sulfuric to phosphoric acid ratio

Ammonia Synthesis using Ti and Nb Nitride Nano-particles Prepared by Mesoporous Graphitic C3N4

KAUST Repository

Kumagai, Hiromu; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

2015-01-01

TiN and NbN nanoparticles were synthesized from mesoporous graphitic C3N4 (mpg-C3N4) as a reactive template and used as the catalyst for ammonia synthesis. The obtained TiN and NbN nanoparticles possess high surface areas of 299 and 275 m2 g-1

Performance Limits and IR Design Challenges of a Possible LHC Luminosity Upgrade Based on Nb-Ti SC Magnet Technology

CERN Document Server

Brüning, Oliver Sim; Ostojic, R; Rossi, L; Ruggiero, F; Scandale, Walter; Taylor, T

2004-01-01

We investigate the maximum LHC performance for a standard IR design based on classical NbTi insertion magnets. We include in our analysis a ternary Nb-based ductile allow such as NbTi(Ta), a less developed but relatively cheap superconducting material which may allow to gain about 1 T in the peak field in the coils, and discuss the corresponding luminosity reach for a possible LHC upgrade compared to that based on Nb$_{3}$Sn magnets.

Obtaining beta phase in Ti through processing in high energy mill powders of Ti and Nb; Obtencao de fase beta no Ti atraves de processamento em moinho de alta energia de pos de Ti e Nb

Energy Technology Data Exchange (ETDEWEB)

Milanez, Mateus; Ferretto, Aline; Rocha, Marcio Roberto da; Arnt, Angela Coelho [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil). Departamento de Engenharia de Materiais; Milanez, Alexandre [Faculdade SATC (FASATC), Criciuma, SC (Brazil). Departamento de Engenharia Mecanica; Schaeffer, Lirio [Universidade Federal do Rio Grande do Sul (LdTM/UFRGS), RS (Brazil). Lab. de Transformacao Mecanica

2014-07-01

An orthopedic implant, ideal, must meet the requirements of biocompatibility, have good mechanical properties among others. Titanium and Niobium exhibit biocompatibility and the β-Ti phase relationships have the highest strength / weight among all titanium alloys, presenting lower values of elastic modulus. The alloy has mechanically produced specific microstructural characteristics and improved mechanical properties compared with conventional powder metallurgy. In this study, a titanium alloy with different additions of niobium was used. The metal powders were mixed via mechanical alloy in high energy mill (attritor). The powder samples were analyzed by X-ray diffraction (X-RD) and property held by adhesive wear testing with a Pin-on-Disk. The present study revealed that through the high-energy milling is possible the atomic interaction between Ti and Nb particles and the mechanical properties are affected by the concentration of Nb. (author)

Transmission electron microscopy of aged Ti-10Mo-20Nb alloy after hot swaging; Microscopia eletronica de transmissao da liga Ti-10Mo-20Nb envelhecida apos forjamento a quente

Energy Technology Data Exchange (ETDEWEB)

Gabriel, Sinara Borborema, E-mail: sinarab@msn.com [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil); Baldan, Renato, E-mail: renatobaldan@gmail.com [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Torres, Juliana; Oliveira, Nathalia Rodrigues, E-mail: juliana_torres_5@hotmail.com, E-mail: nathalia_roliveira@yahoo.com.br [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Mei, Paulo Roberto, E-mail: cnunes@demar.eel.usp.br, E-mail: pmei@fem.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil)

2014-08-15

Ti alloys are widely used in biomedical applications. Within this class, metastable β -Ti alloys stand, because through thermomechanical processing it is possible to obtain mechanical properties and in particular one suitable Young's modulus for biomedical applications. These alloys require high mechanical strength and a low Young's modulus to avoid stress shielding. Preliminary studies showed that the microstructure of the Ti-10Mo- 20Nb alloy after cold forging and aging 500 °C/24 h consisted in bimodal distribution of α phase in the β matrix. The aim of this study was to characterize the microstructure of Ti-10Mo-20Nb alloy after hot forging and aging at 500 °C for 24 hours. Microstructural characterization consisted of analyzes by X-ray diffraction and transmission electron microscopy. According to the results, while the cold forging resulted in a bimodal α distribution in the β matrix, hot forging resulted in a thin and homogeneous α precipitation in the β matrix. (author)

Characterization of nitride formation in NbTi-50% weight alloy by x-ray diffraction

International Nuclear Information System (INIS)

Teixeira, S.R.

1990-01-01

Titanium and niobium are so main metals for technology as structural materials, refractories and resistance alloys for corrosion. This interest is based in application of this metals and alloys in aerospacial industry, nuclear reactors, construction of superconductor magnets and in the production of superconductors wires. The NbTi (50% wt. Ti) alloy nitretation under nitrogen atmosphere (p + 760 mm) at 800 - 1000 C was studied by x-ray diffractometry. TEM and optical metallography. During the reaction the two phases (Ti sub(2) N - ε and TiN - δ) growed continuously, the (Ti sub(2) N, N sub(2)) reaction front growed faster than the (TiN,N sub(2)). A method for study the scale growing was proposed using x-ray diffractometry data. By using this method, the growth of TiN scale was analysed and the activation energy of 19 Kcal/mole was determinated using a linear timming law indicating a mechanism not controlled by diffusion through TiN layer. The present results suggest that the diffusion through the tight tunnels, rich in Nb, allow a fast transport of nitrogen through the TiN layer. (author)

Glass forming ability and mechanical properties of the NiZrTiSi amorphous alloys modified with Al, Cu and Nb additions

International Nuclear Information System (INIS)

Czeppe, Tomasz; Ochin, Patrick; Sypien, Anna

2007-01-01

The composition of the amorphous alloy Ni 59 Zr 20 Ti 16 Si 5 was modified with 2-9 at.% additions of Cu, Al and Nb. The ribbons and the bars 2.7 mm in diameter were prepared by melt spinning and injection casting from the alloys of the compositions: Ni 56 Zr 18 Ti 16 Si 5 Al 3 Cu 2 , Ni 56 Zr 18 Ti 13 Al 6 Si 5 Cu 2 , Ni 56 Zr 16 Ti 12 Nb 9 Al 3 Cu 2 Si 2 and Ni 56 Zr 16 Ti 12 Nb 6 Al 6 Cu 2 Si 2 . All ribbons were amorphous up to the resolution of the X-ray diffraction and conventional transmission electron microscopy, however rods were partially crystalline. Increase of Al content lowered and Nb content slightly increased crystallization start temperature T x and glass transition temperature T g . The influence of composition changes on the overcooled liquid range ΔT was more complicated. The increase of Nb and decrease of Ti and Zr content led to the remarkable increase of the liquidus temperature T l . As a result GFA calculated as T g /T l was lowered to the values about 0.63 for 6 and 9 at.% Nb addition. The activation energies for primary crystallization in alloy with 6 at.% Al and 6 at.% of Nb, were determined. The changes of tensile test strength and microhardness with Al and Nb additions showed hardening effect caused by Nb additions and increase in fracture strength with increasing Al content

Hadfield steels with Nb and Ti carbides

International Nuclear Information System (INIS)

Vatavuk, J.; Goldenstein, H.

1987-01-01

The Hadfield Steels and the mechanisms responsible for its high strain hardening rate were reviewed. Addition of carbide forming alloying elements to the base compostion was discussed, using the matrix sttel concept. Three experimental crusher jaws were cast, with Nb and Nb + Ti added to the usual Hadfiedl compostion, with enough excess carbon to allow the formation of MC carbides. Samples for metallographic analysis were prepared from both as cast and worn out castings. The carbic morphology was described. Partition of alloying elements was qualitatively studied, using Energy Dispersive Espectroscopy in SEM. The structure of the deformed layer near the worn surface was studied by optical metalography and microhardness measurements. The results showed that fatigue cracking is one of the wear mechanisms is operation in association with the ciclic work hardening of the surface of worn crusher jaws. (Author) [pt

Nb3Sn conductor development for the ITER magnets

International Nuclear Information System (INIS)

Mitchell, N.

1997-01-01

The ITER magnet system consists of Toroidal Field (TF) coils, Poloidal Field (PF) coils, the Central Solenoid (CS) and error field correction coils (CC). The conductors for the coils are Nb 3 Sn or NbTi cable in conduit type, forced flow cooled with supercritical helium having a maximum operating current in the range 40-60 kA. To qualify the Nb 3 Sn conductor, two large model coils (energy up to 640 MJ) are being wound by the Home Teams of the Parties to the ITER EDA Agreement. A total of 24 t of strand has been completed for the CS model coil and 4 t for the TF model coil, and fabricated into 7 km of conductor in unit lengths up to 210 m, by an international collaboration involving 12 companies in Europe, Japan, Russia and the USA

Effect of applied bias voltage on corrosion-resistance for TiC 1- xN x and Ti 1- xNb xC 1- yN y coatings

Science.gov (United States)

Caicedo, J. C.; Amaya, C.; Yate, L.; Aperador, W.; Zambrano, G.; Gómez, M. E.; Alvarado-Rivera, J.; Muñoz-Saldaña, J.; Prieto, P.

2010-02-01

Corrosion-resistance behavior of titanium carbon nitride (Ti-C-N) and titanium niobium carbon nitride (Ti-Nb-C-N) coatings deposited onto Si(1 0 0) and AISI 4140 steel substrates via r.f. magnetron sputtering process was analyzed. The coatings in contact with a solution of sodium chloride at 3.5% were studied by Tafel polarization curves and impedance spectroscopy methods (EIS). Variations of the bias voltage were carried out for each series of deposition to observe the influence of this parameter upon the electrochemical properties of the coatings. The introduction of Nb in the ternary Ti-C-N film was evaluated via X-ray diffraction (XRD) analysis. The structure was characterized by using Raman spectroscopy to identify ternary and quaternary compounds. Surface corrosion processes were characterized using optical microscopy and scanning electron microscopy (SEM). XRD results show conformation of the quaternary phase, change in the strain of the film, and lattice parameter as the effect of the Nb inclusion. The main Raman bands were assigned to interstitial phases and "impurities" of the coatings. Changes in Raman intensities were attributed to the incorporation of niobium in the Ti-C-N structure and possibly to resonance enhancement. Finally, the corrosion data obtained for Ti-C-N were compared with the results of corrosion tests of Ti-Nb-C-N coating. The results obtained showed that the incorporation of niobium to Ti-C-N coatings led to an increase in the corrosion-resistance. On another hand, an increase in the bias voltage led to a decrease in the corrosion-resistance for both Ti-C-N and Ti-Nb-C-N coatings.

Layered surface structure of gas-atomized high Nb-containing TiAl powder and its impact on laser energy absorption for selective laser melting

Science.gov (United States)

Zhou, Y. H.; Lin, S. F.; Hou, Y. H.; Wang, D. W.; Zhou, P.; Han, P. L.; Li, Y. L.; Yan, M.

2018-05-01

Ti45Al8Nb alloy (in at.%) is designed to be an important high-temperature material. However, its fabrication through laser-based additive manufacturing is difficult to achieve. We present here that a good understanding of the surface structure of raw material (i.e. Ti45Al8Nb powder) is important for optimizing its process by selective laser melting (SLM). Detailed X-ray photoelectron spectroscopy (XPS) depth profiling and transmission electron microscopy (TEM) analyses were conducted to determine the surface structure of Ti45Al8Nb powder. An envelope structure (∼54.0 nm in thickness) was revealed for the powder, consisting of TiO2 + Nb2O5 (as the outer surface layer)/Al2O3 + Nb2O5 (as the intermediate layer)/Al2O3 (as the inner surface layer)/Ti45Al8Nb (as the matrix). During SLM, this layered surface structure interacted with the incident laser beam and improved the laser absorptivity of Ti45Al8Nb powder by ∼32.21%. SLM experiments demonstrate that the relative density of the as-printed parts can be realized to a high degree (∼98.70%), which confirms good laser energy absorption. Such layered surface structure with appropriate phase constitution is essential for promoting SLM of the Ti45Al8Nb alloy.

Wear resistance of laser-deposited boride reinforced Ti-Nb-Zr-Ta alloy composites for orthopedic implants

International Nuclear Information System (INIS)

Samuel, Sonia; Nag, Soumya; Scharf, Thomas W.; Banerjee, Rajarshi

2008-01-01

The inherently poor wear resistance of titanium alloys limits their application as femoral heads in femoral (hip) implants. Reinforcing the soft matrix of titanium alloys (including new generation β-Ti alloys) with hard ceramic precipitates such as borides offers the possibility of substantially enhancing the wear resistance of these composites. The present study discusses the microstructure and wear resistance of laser-deposited boride reinforced composites based on Ti-Nb-Zr-Ta alloys. These composites have been deposited using the LENS TM process from a blend of elemental Ti, Nb, Zr, Ta, and boron powders and consist of complex borides dispersed in a matrix of β-Ti. The wear resistance of these composites has been compared with that of Ti-6Al-4V ELI, the current material of choice for orthopedic femoral implants, against two types of counterfaces, hard Si 3 N 4 and softer SS440C stainless steel. Results suggest a substantial improvement in the wear resistance of the boride reinforced Ti-Nb-Zr-Ta alloys as compared with Ti-6Al-4V ELI against the softer counterface of SS440. The presence of an oxide layer on the surface of these alloys and composites also appears to have a substantial effect in terms of enhanced wear resistance

TEXTURE AND MECHANICAL BEHAVIOUR OF Ti AND Nb-Ti STABILIZED IF STEELS

Directory of Open Access Journals (Sweden)

Fabio Moreira da Silva Dias

2013-12-01

Full Text Available An analysis of the crystallographic texture and mechanical behavior of two types of IF steels is presented. Two steels, Ti and Nb-Ti, were submitted to different thermal annealing cycles in a continuous hot-dip galvanizing line, heat treated at temperatures of 860°C and 760°C. The more relevant characteristics of mechanical properties are evaluated. The crystallographic texture of the samples is determined by electron diffraction technique of back-scattering (SEM-EBSD. The intensity of orientation //ND is evaluated and compared. Metallographic characterization is done, and the ferritic grain size is measured with optical microscopy. The mechanical behavior of materials is characterized in the tensile test with 80 mm gauge length.

Mechanical characterization of Ti-12Mo-13Nb alloy for biomedical application hot swaged and aged

Energy Technology Data Exchange (ETDEWEB)

Gabriel, Sinara Borborema; Rezende, Monica Castro; Almeida, Luiz Henrique de, E-mail: sinara@metalmat.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Engenharia Metalurgica e de Materiais; Dille, Jean [Universite Libre de Bruxelles, Brussels (Belgium); Mei, Paulo [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Departamento de Engenharia Mecanica; Baldan, Renato; Nunes, Carlos Angelo [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Departamento de Engenharia de Materiais

2015-07-01

Beta titanium alloys were developed for biomedical applications due to the combination of its mechanical properties including low elasticity modulus, high strength, fatigue resistance, good ductility and with excellent corrosion resistance. With this perspective a metastable beta titanium alloy Ti-12Mo-13Nb was developed with the replacement of both vanadium and aluminum from the traditional alloy Ti-6Al-4V. This paper presents the microstructure, mechanical properties of the Ti-12Mo-13Nb hot swaged and aged at 500 deg C for 24 h under high vacuum and then water quenched. The alloy structure was characterized by X-ray diffraction and transmission electron microscopy. Tensile tests were carried out at room temperature. The results show a microstructure consisting of a fine dispersed α phase in a β matrix and good mechanical properties including low elastic modulus. The results indicate that Ti-12Mo-13Nb alloy can be a promising alternative for biomedical application. (author)

Obtaining beta phase in Ti through processing in high energy mill powders of Ti and Nb

International Nuclear Information System (INIS)

Milanez, Mateus; Ferretto, Aline; Rocha, Marcio Roberto da; Arnt, Angela Coelho; Milanez, Alexandre; Schaeffer, Lirio

2014-01-01

An orthopedic implant, ideal, must meet the requirements of biocompatibility, have good mechanical properties among others. Titanium and Niobium exhibit biocompatibility and the β-Ti phase relationships have the highest strength / weight among all titanium alloys, presenting lower values of elastic modulus. The alloy has mechanically produced specific microstructural characteristics and improved mechanical properties compared with conventional powder metallurgy. In this study, a titanium alloy with different additions of niobium was used. The metal powders were mixed via mechanical alloy in high energy mill (attritor). The powder samples were analyzed by X-ray diffraction (X-RD) and property held by adhesive wear testing with a Pin-on-Disk. The present study revealed that through the high-energy milling is possible the atomic interaction between Ti and Nb particles and the mechanical properties are affected by the concentration of Nb. (author)

Effects of cold-working on pinning behaviour and critical current densities in NbTi-based superconductors

International Nuclear Information System (INIS)

Yamada, Y.; Murase, S.; Wada, H.; Tachikawa, K.

1985-01-01

The effects of cold-working on high-field pinning behaviour at 1.8 K and 4.2 K have been studied for multifilamentary NbTi, NbTiHf and NbTiTa superconductors, which were subjected to cold-working, heat treatment and cold-working, in sequence. It is found that the cold-working, either before or after heat treatment, shifts the peak in pinning force density to a higher field, while the maximum pinning force value is first increased with increasing amount of cold-working, and then decreased. This result can not be predicted by existing pinning theories, and we conclude that for pinning behaviour induced by cold-working, not only the introduction of pinning centres but also their size and spacing must be taken into account. (author)

Effects of intramedullary nails composed of a new β-type Ti-Nb-Sn alloy with low Young's modulus on fracture healing in mouse tibiae.

Science.gov (United States)

Fujisawa, Hirokazu; Mori, Yu; Kogure, Atsushi; Tanaka, Hidetatsu; Kamimura, Masayuki; Masahashi, Naoya; Hanada, Shuji; Itoi, Eiji

2018-01-23

The influence of Young's moduli of materials on the fracture healing process remains unclear. This study aimed to assess the effects of intramedullary nails composed of materials with low Young's moduli on fracture repair. We previously developed a β-type Ti-Nb-Sn alloy with low Young's modulus close to that of human cortical bone. Here, we prepared two Ti-Nb-Sn alloys with Young's moduli of 45 and 78 GPa by heat treatment, and compared their effects on fracture healing. Fracture and nailing were performed in the right tibiae of C57BL/6 mice. The bone healing process was evaluated by microcomputed tomography (micro-CT), histomorphometry, and RT-PCR. We found larger bone volumes of fracture callus in the mice treated with the 45-GPa Ti-Nb-Sn alloy as compared with the 78-GPa Ti-Nb-Sn alloy in micro-CT analyses. This was confirmed with histology at day 14, with accelerated new bone formation and cartilage absorption in the 45-GPa Ti-Nb-Sn group compared with the 78-GPa Ti-Nb-Sn group. Acp5 expression was lower in the 45-GPa Ti-Nb-Sn group than in the 78-GPa Ti-Nb-Sn group at day 10. These findings indicate that intramedullary fixation with nails with a lower Young's modulus offer a greater capacity for fracture repair. Our 45-GPa Ti-Nb-Sn alloy is a promising material for fracture treatment implants. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

KAUST Repository

Arashi, Takuya

2014-09-01

Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

KAUST Repository

Arashi, Takuya; Seo, Jeongsuk; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

2014-01-01

Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

Nb and Ta layer doping effects on the interfacial energetics and electronic properties of LaAlO3/SrTiO3 heterostructure: first-principles analysis.

Science.gov (United States)

Nazir, Safdar; Behtash, Maziar; Cheng, Jianli; Luo, Jian; Yang, Kesong

2016-01-28

The two-dimensional electron gas (2DEG) formed at the n-type (LaO)(+1)/(TiO2)(0) interface in the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) has emerged as a prominent research area because of its great potential for nanoelectronic applications. Due to its practical implementation in devices, desired physical properties such as high charge carrier density and mobility are vital. In this respect, 4d and 5d transition metal doping near the interfacial region is expected to tailor electronic properties of the LAO/STO HS system effectively. Herein, we studied Nb and Ta-doping effects on the energetics, electronic structure, interfacial charge carrier density, magnetic moment, and the charge confinements of the 2DEG at the n-type (LaO)(+1)/(TiO2)(0) interface of LAO/STO HS using first-principles density functional theory calculations. We found that the substitutional doping of Nb(Ta) at Ti [Nb(Ta)@Ti] and Al [Nb(Ta)@Al] sites is energetically more favorable than that at La [Nb(Ta)@La] and Sr [Nb(Ta)@Sr] sites, and under appropriate thermodynamic conditions, the changes in the interfacial energy of HS systems upon Nb(Ta)@Ti and Nb(Ta)@Al doping are negative, implying that the formation of these structures is energetically favored. Our calculations also showed that Nb(Ta)@Ti and Nb(Ta)@Al doping significantly improve the interfacial charge carrier density with respect to that of the undoped system, which is because the Nb(Ta) dopant introduces excess free electrons into the system, and these free electrons reside mainly on the Nb(Ta) ions and interfacial Ti ions. Hence, along with the Ti 3d orbitals, the Nb 4d and Ta 5d orbitals also contribute to the interfacial metallic states; accordingly, the magnetic moments on the interfacial Ti ions increase significantly. As expected, the Nb@Al and Ta@Al doped LAO/STO HS systems show higher interfacial charge carrier density than the undoped and other doped systems. In contrast, Nb@Ti and Ta@Ti doped systems may

Precipitation Behaviour of Carbonitrides in Ti-Nb-C-N Microalloyed Steels and an Engineering Application with Homogenously Precipitated Nano-particles

Directory of Open Access Journals (Sweden)

Yanlin WANG

2015-11-01

Full Text Available A thermodynamic model enabling calculation of equilibrium carbonitride composition and relative amounts as a function of steel composition and temperature has been developed previously based on the chemical equilibrium method. In the present work, actual carbonitride precipitation behaviour has been verified in the Ti-Nb-C-N microalloyed steels. The Ti microalloyed steel after refining with 0.012 % Nb exhibited highly improved tensile strength without sacrificing ductility. According to further detailed SEM and TEM analysis, the improved mechanical properties of Ti/Nb microalloyed steel could be attributed to the larger solubility of Nb and Ti, inducing fine dispersion of the carbonitrides with particle size of 2 – 10 nm in the ferrite matrix.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9622

Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis; Investigacao da resistencia a corrosao da liga Ti-13Nb-13Zr por meio de tecnicas eletroquimicas e de analise de superficie

Energy Technology Data Exchange (ETDEWEB)

Assis, Sergio Luiz de

2006-07-01

In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis; Investigacao da resistencia a corrosao da liga Ti-13Nb-13Zr por meio de tecnicas eletroquimicas e de analise de superficie

Energy Technology Data Exchange (ETDEWEB)

Assis, Sergio Luiz de

2006-07-01

In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

Superconducting ac cable

Science.gov (United States)

Schmidt, F.

1980-11-01

The components of a superconducting 110 kV ac cable for power ratings or = 2000 MVA were developed. The cable design is of the semiflexible type, with a rigid cryogenic envelope containing a flexible hollow coaxial cable core. The cable core consists of spirally wound Nb-A1 composite wires electrically insulated by high pressure polyethylene tape wrappings. A 35 m long single phase test cable with full load terminals rated at 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of this cable design.

Superconducting ac cable

International Nuclear Information System (INIS)

Schmidt, F.

1980-01-01

The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.) [de

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

International Nuclear Information System (INIS)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin; Song, Hyo Seok; Lee, Yong Deuk

2002-01-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al 2 O 3 on the melt surface. A small addition of CaO-Al 2 O 3 synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate

The effect of Ti and Nb on nitrogen dissolution reaction in stainless steel melt

Energy Technology Data Exchange (ETDEWEB)

Jang, Min Whan; Hong, In Kook; Pak, Jong Jin [Hanyang Univ., Ansan (Korea, Republic of); Song, Hyo Seok; Lee, Yong Deuk [POSCO, Pohang (Korea, Republic of)

2002-03-01

A kinetic study of nitrogen dissolution in STS304 stainless steel melt containing Ti and Nb has been carried out at 1500 degree C using an induction furnace and a levitation melting furnace. At low O and S levels, the nitrogen dissolution rate showed the first-order kinetics being controlled by the mass transfer of nitrogen in the melt. Ti addition to STS304 stainless melt significantly retarded the nitrogen dissolution rate by the formation of solid Ti oxide layer adhered on the melt surface. Nb did not affect the rate of nitrogen dissolution. In the levitation melting experiment where the oxide layer was removed from the melt surface, Ti did not retard the nitrogen dissolution rate. Simultaneous addition of Ti and Al increased the dissolution rate by the formation of non-wetting Al{sub 2}O{sub 3} on the melt surface. A small addition of CaO-Al{sub 2}O{sub 3} synthetic flux to Ti containing melt was very effective to remove the oxide layer, hence to increase the nitrogen dissolution rate.

Comparative evaluation of metal ions release from titanium and Ti-6Al-7Nb into bio-fluids

Directory of Open Access Journals (Sweden)

Lori A Joseph

2009-01-01

Full Text Available Background: The study was designed to investigate the effects of pH, chloride ions and nature of some bio-fluids on the amount of metal ions released from titanium and TiAl 6 Nb 7 plates following incubation in actual and simulated bio-fluids over time. Methods: The amounts of released metal ions from commercially pure titanium (CpTi and TiAl 6 Nb 7 of surgical grade on immersion in 20 mL Hank′s solution of pH 4.0 or 7.0, Hank′s solution of high chloride ions concentration, Whole Blood Serum (WBS and Phosphate Buffered Saline (PBS at 37° C were determined over an incubation time of 20 weeks using atomic absorption spectrophotometry. The levels of released metal ions were compared by two-way ANOVA and Duncan′s post-hoc tests. The amounts of titanium ions released by the samples were analyzed by Pearson′s correlation. Results: TiAl 6 Nb 7 plate showed no release of Ti ions into the test solutions until after 12 weeks of incubation, while Ti ions were released from the CpTi plate from the 1 day immersion time. The re-lease of measurable amount of Al ions from TiAl 6 Nb 7 was after 12 weeks of incubation. The rate of release of Ti and Al ions from the samples increased initially with incubation time and then stabilized due to adsorption-desorption equilibrium. Conclusion: The results showed that variations in pH and chloride ions of the test media has a sig-nificant effect on the amounts of Ti ions released, while increase in chloride ions concentration sig-nificantly elevates the release of Al ions into the bio-fluids.

Mass production system and technology of NbTi superconductors

International Nuclear Information System (INIS)

Fukutsuka, Toshiro; Monju, Yoshiyuki; Tatara, Isamu; Noguchi, Masataka; Yokochi, Katsuhiro; Matsubara, Mitsuharu.

1984-01-01

A mass production system for NbTi superconductors is described, involving vacuum arc melting of the alloys, hot hydrostatic extrusion of the composite billets and special drawing and stranding techniques for the rods and wires. The qualities required for superconducting wires are assured by a variety of instrument measurement and inspection techniques drawn from accumulated cryogenic experiences. (author)

Oxidation characteristics of Ti-14Al-21Nb alloy at high temperature in purified oxygen; Ti-14Al?-21Nb gokin no sansochu ni okeru koon sanka tokusei

Energy Technology Data Exchange (ETDEWEB)

Akai, M; Taniguchi, S; Shibata, T [Osaka University, Osaka (Japan). Faculty of Engineering

1994-10-20

The Ti-14Al-21Nb alloy called Super {alpha}{sub 2} is an alloy which has been improved of plastic transformation ability by adding Nb into Ti3Al with high specific strength, and is used for member materials in aircraft engines. In order to identify its oxidation characteristics, this paper discusses the oxidation characteristics under purified oxygen and atmospheric pressure in temperatures ranging from 1000 K to 1300 K. The experiment made a button-formed ingot with a diameter of 50 mm and a thickness of about 10 mm by melting and thermal refining, and used a thermobalance. Main conclusion thus obtained may be summarized as follows: the amount of increase due to oxidation after 100 ks oxidation at 1000 K is very small; oxidation between 1100 K and 1200 K follows nearly the parabolic rate laws; the scale consisted mainly of rutile, but a thin alumina concentration layer is formed; Nb is concentrated in the rutile-alumina mixed layer, and local fracture and regeneration are repeated at temperatures higher than 1300 K. 21 refs., 8 figs., 2 tabs.

Mechanical properties and microstructure of Ti-35.5Nb-5.7Ta beta alloy.

Science.gov (United States)

Bartakova, S; Prachar, P; Dvorak, I; Hruby, V; Vanek, J; Pospichal, M; Svoboda, E; Martikan, A; Konecna, H; Sedlak, I

2015-01-01

Titanium and titanium alloys represent generally accepted metallic biomaterials for clinical dentistry and dental implantology. In this paper, we present a Ti-35.5Nb-5.7Ta alloy with a special respect to its microstructure and mechanical characteristics, such as Young modulus of elasticity. Three thermal treatments differing in temperature and time of annealing were used during the Ti-35.5Nb-5.7Ta processing in order to evaluate the effects of ageing, melting annealing, and annealing on mechanical characteristics and microstructure. Using microscopy, the alloy was analyzed and the differences in shares of beta phase grains, alpha particles and precipitates evaluated. The three thermal treatments were evaluated also from technological point of view. The following thermal treatment was found optimal for the Ti-35.5Nb-5.7Ta alloy: melting annealing at 800 °C for 0.5 hour followed by a cold swaging with a 52-79 % deformation, and final hardening at 500 °C for 2 hours in water(Tab. 2, Fig. 3, Ref. 24).

Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis

International Nuclear Information System (INIS)

Assis, Sergio Luiz de

2006-01-01

In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

Thermal conductivity measurements of impregnated Nb3Sn coil samples in the temperature range of 3.5 K to 100 K

Science.gov (United States)

Koettig, T.; Maciocha, W.; Bermudez, S.; Rysti, J.; Tavares, S.; Cacherat, F.; Bremer, J.

2017-02-01

In the framework of the luminosity upgrade of the LHC, high-field magnets are under development. Magnetic flux densities of up to 13 T require the use of Nb3Sn superconducting coils. Quench protection becomes challenging due to the high stored energy density and the low stabilizer fraction. The thermal conductivity and diffusivity of the combination of insulating layers and Nb3Sn based cables are an important thermodynamic input parameter for quench protection systems and superfluid helium cooling studies. A two-stage cryocooler based test stand is used to measure the thermal conductance of the coil sample in two different heat flow directions with respect to the coil package geometry. Variable base temperatures of the experimental platform at the cryocooler allow for a steady-state heat flux method up to 100 K. The heat is applied at wedges style copper interfaces of the Rutherford cables. The respective temperature difference represents the absolute value of thermal conductance of the sample arrangement. We report about the measurement methodology applied to this kind of non-uniform sample composition and the evaluation of the used resin composite materials.

Severe plastic deformation of α+β Ti-5Ta-1.8Nb alloy by cryo-rolling

International Nuclear Information System (INIS)

Dasgupta, Arup; Parida, Pradyumna Kumar; Saroja, S.; Vijayalakshmi, M.

2010-01-01

The α-β (β ∼ 8%) Ti5Ta1.8Nb alloy is under development at IGCAR for reprocessing applications owing to its superior corrosion resistance and weldability. A possible method to strengthen the alloy is to engineer the grain size to finer dimensions through severe plastic deformation (SPD). A detailed analysis of the study of evolution of microstructure and micro-texture in the SPD Ti-Ta-Nb alloy is presented

Transmission electron microscopy of Ti-12Mo-13Nb Alloy aged after heat forging; Microscopia eletronica de transmissao da liga Ti-12Mo-13Nb envelhecida apos forjamento a quente

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Nathalia Rodrigues [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Baldan, Renato [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Escola de Engenharia; Nunes, Carlos Angelo; Mei, Paulo Roberto [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil); Gabriel, Sinara Borborema [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

2014-06-15

Metastable β-Ti alloys possess mechanical properties, in particular a elastic modulus that depends not only on its composition but also the applied thermomechanical treatments. These alloys require high mechanical strength and a low Young’s modulus to avoid stress shielding. Preliminary studies on the development of Ti- 13Nb-12Mo alloy showed than the better properties were obtained at aged at 500 ° C / 24 h after cold forging , whose microstructure consisted of bimodal α phase in the β matrix. In this work, Ti-12Mo-13Nb alloy was heat forged and aged at 500 deg C for 24h and the microstructure was analyzed by employing X-ray diffraction and transmission electron microscopy. According to the results, while the cold forging resulted in bimodal α phase in the β matrix, hot forging resulted in a fine and homogeneous α phase in the β matrix. (author)

Corrosion and bioactivity performance of graphene oxide coating on TiNb shape memory alloys in simulated body fluid.

Science.gov (United States)

Saud, Safaa N; Hosseinian S, Raheleh; Bakhsheshi-Rad, H R; Yaghoubidoust, F; Iqbal, N; Hamzah, E; Ooi, C H Raymond

2016-11-01

In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of TiNb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35μm to 45μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated TiNb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37°C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO thin films

Directory of Open Access Journals (Sweden)

Subodh K. Gautam

2015-12-01

Full Text Available The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1 mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

Phase composition, microstructure, and mechanical properties of porous Ti-Nb-Zr alloys prepared by a two-step foaming powder metallurgy method.

Science.gov (United States)

Rao, X; Chu, C L; Zheng, Y Y

2014-06-01

Porous Ti-Nb-Zr alloys with different porosities from 6.06 to 62.8% are prepared by a two-step foaming powder metallurgy method using TiH2, Nb, and Zr powders together with 0 to 50wt% of NH4HCO3. The effects of the amounts of Nb and Zr as well as the sintering temperature (1473 to 1673K) on their phase composition, porosity, morphology, and mechanical characteristics are investigated. By controlling the porosity, Nb and Zr concentrations as well as the sintering temperature, porous Ti-Nb-Zr alloys with different mechanical properties can be obtained, for example, the hardness between 290 and 63HV, the compressive strength between 1530.5 and 73.4MPa, and the elastic modulus between 10.8 and 1.2GPa. The mechanical properties of the sintered porous Ti-Nb-Zr alloys can be tailored to match different requirements for the human bones and are thus potentially useful in the hard tissue implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Measurement of stability of cabled conductors cooled by He I at reduced temperature, or He II

International Nuclear Information System (INIS)

Hsu, Y.H.; Purcell, J.R.; Chen, W.Y.; Alcorn, J.S.

1980-09-01

Stability tests of cabled NbTi alloy conductor are underway at the General Atomic High Field Test Facility, in support of the Team One effort of the DOE 12 Tesla Coil Development Program. A background field of up to 10 tesla within a 20 cm bore is provided by a nested pair of 4.2 0 K bath cooled NbTi coils. An insulated bore insert tube (coldfinger) is provided in order to perform heat pulse/recovery tests of coiled samples in cooling regimes anticipated for the 1 m O.D. coil to be tested at the LLNL 12 tesla facility during FY 82. Specifically, tests are being performed in the 2.5 to 3 0 K He I, and saturated superfluid (He II) regimes. The testing apparatus, procedures, and initial results are presented

Neutron scattering studies of the defect structures in TiCsub(1-x) and NbCsub(1-x)

International Nuclear Information System (INIS)

Moisy-Maurice, V.; Novion, C.H. de; Lorenzelli, N.

1981-08-01

Single crystals of TiCsub(1-x) and NbCsub(1-x) were studied by elastic neutron diffuse scattering at room temperature in the (110) reciprocal lattice plane; the spectra of TiCsub(0.76), TiCsub(0.79) and NbCsub(0.73) were analysed by the Sparks and Borie method, which allowed to determine the first Cowley-Warren short-range order coefficients and a shortening (0.03 A) of the average first neighbour metal-carbon distances. The order-disorder transformation in TiCsub(1-x) (0.52 0 C) and critical coefficients β were determined. The results are discussed in terms of interatomic pair potentials

Surface structures and osteoblast response of hydrothermally produced CaTiO{sub 3} thin film on Ti-13Nb-13Zr alloy

Energy Technology Data Exchange (ETDEWEB)

Park, Jin-Woo, E-mail: jinwoo@knu.ac.kr [Department of Periodontology, School of Dentistry, Kyungpook National University, 188-1, Samduk 2Ga, Jung-Gu, Daegu 700-412 (Korea, Republic of); Tustusmi, Yusuke [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental Univeristy, Tokyo 101-0062 (Japan); Lee, Chong Soo; Park, Chan Hee [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kim, Youn-Jeong; Jang, Je-Hee [Department of Periodontology, School of Dentistry, Kyungpook National University, 188-1, Samduk 2Ga, Jung-Gu, Daegu 700-412 (Korea, Republic of); Khang, Dongwoo; Im, Yeon-Min [School of Materials Science and Engineering, Gyeongsang National University, Jinju 600-701 (Korea, Republic of); Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao [Department of Metals, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental Univeristy, Tokyo 101-0062 (Japan)

2011-06-15

This study investigated the surface characteristics and in vitro biocompatibility of a titanium (Ti) oxide layer incorporating calcium ions (Ca) obtained by hydrothermal treatment with or without post heat-treatment in the Ti-13Nb-13Zr alloy. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. In vitro biocompatibility of the Ca-containing surfaces was assessed in comparison with untreated surfaces using a pre-osteoblast cell line. Hydrothermal treatment produced a crystalline CaTiO{sub 3} layer. Post heat-treatment at 400 deg. C for 2 h in air significantly decreased water contact angles in the CaTiO{sub 3} layer (p < 0.001). The Ca-incorporated alloy surfaces displayed markedly increased cell viability and ALP activity compared with untreated surfaces (p < 0.001), and also an upregulated expression of various integrin genes ({alpha}1, {alpha}2, {alpha}5, {alpha}v, {beta}1 and {beta}3) at an early incubation time-point. Post heat-treatment further increased attachment and ALP activity in cells grown on Ca-incorporated Ti-13Nb-13Zr alloy surfaces. The results indicate that the Ca-incorporated oxide layer produced by hydrothermal treatment and a simple post heat-treatment may be effective in improving bone healing in Ti-13Nb-13Zr alloy implants by enhancing the viability and differentiation of osteoblastic cells.

Tribological Testing, Analysis and Characterization of D.C. Magnetron Sputtered Ti-Nb-N Thin Film Coatings on Stainless Steel

Science.gov (United States)

Joshi, Prathmesh

To enhance the surface properties of stainless steel, the substrate was coated with a 1μm thick coating of Ti-Nb-N by reactive DC magnetron sputtering at different N2 flow rates, substrate biasing and Nb-Ti ratio. The characterization of the coated samples was performed by the following techniques: hardness by Knoop micro-hardness tester, phase analysis by X-ray Diffraction (XRD), compositional analysis by Energy Dispersive X-ray Spectroscopy (EDS) and adhesion by scratch test. The tribology testing was performed on linearly reciprocating ball-on-plate wear testing machine and wear depth and wear volume were evaluated by white light interferometer. The micro-hardness test yielded appreciable enhancement in the surface hardness with the highest value being 1450 HK. Presence of three prominent phases namely NbN, Nb2N3 and TiN resulted from the XRD analysis. EDS analysis revealed the presence of Ti, Nb and Nitrogen. Adhesion was evaluated on the basis of critical loads for cohesive (Lc1) and adhesive (Lc2) failures with values varying between 7-12 N and 16-25 N respectively, during scratch test for coatings on SS substrates.

Tribological behavior and self-healing functionality of TiNbCN-Ag coatings in wide temperature range

Science.gov (United States)

Bondarev, A. V.; Kiryukhantsev-Korneev, Ph. V.; Levashov, E. A.; Shtansky, D. V.

2017-02-01

Ag- and Nb-doped TiCN coatings with about 2 at.% of Nb and Ag contents varied between 4.0 and 15.1 at.% were designed as promising materials for tribological applications in a wide temperature range. We report on the structure, mechanical, and tribological properties of TiNbCN-Ag coatings fabricated by simultaneous co-sputtering of TiC0.5 + 10%Nb2C and Ag targets in comparison with those of Ag-free coating. The tribological characteristics were evaluated during constant-temperature tests both at room temperature and 300 °C, as well as during dynamic temperature ramp tests in the range of 25-700 °C. The coating structure and elemental composition were studied by means of X-ray diffraction, scanning and transmission electron microscopy, and glow discharge optical emission spectroscopy. The coating microstructures and elemental compositions inside wear tracks, as well as the wear products, were examined by scanning electron microscopy, energy-dispersive spectroscopy, and Raman spectroscopy. We demonstrate that simultaneous alloying with Nb and Ag permits to overcome the main drawbacks of TiCN coatings such as their relatively high values of friction coefficient at elevated temperatures and low oxidation resistance. It is shown that a relatively high amount of Ag (15 at.%) is required to provide enhanced tribological behavior in a wide temperature range of 25-700 °C. In addition, the prepared Ag-doped coatings demonstrated active oxidation protection and self-healing functionality due to the segregation of Ag metallic particles in damage areas such as cracks, pin-holes, or oxidation sites.

Hydrogenation Properties of Mg-5 wt.% TiCr_10NbX (x=1,3,5) Composites by Mechanical Alloying Process

International Nuclear Information System (INIS)

Kim, Kyeong-Il; Hong, Tae-Whan

2011-01-01

Hydrogen and hydrogen energy have been recognized as clean energy sources and high energy carrier. Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and low cost materials with high hydrogen capacity (about 7.6 wt.%). However, the commercial applications of the Mg hydrides are currently hinder by its high absorption/desorption temperature, and very slow reaction kinetics. However, Ti and Ti based hydrogen storage alloys have been thought to be the third generation of alloys with a high hydrogen capacity, which makes it difficult to handle because of high reactivity. One of the most methods to develop kinetics was addition of transition metal. Therefore, Mg-Ti-Cr-Nb alloy was fabricated to add TiCrNb by hydrogen induced mechanical alloying. TiCrNb systems have included transition metals, low operating temperatures and hydrogen storage materials. As-received specimens were characterized using X-ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) and Thermo Gravimetric analysis/Differential Scanning Calorimetry (TG/DSC). Mg-TiCr_10Nb systems were evaluated for hydrogen kinetics by Sievert’s type Pressure-Composition-Isotherm (PCI) equipment. The operating temperature range was 473, 523, 573 and 623 K.

Is there an ordered tetragonal phase in the Ti3Al-Nb system?

International Nuclear Information System (INIS)

Banerjee, D.

1994-01-01

In a recent series of papers, describing aging transformations in plasma sprayed Ti-24Al-11Nb, Hsiung and co-workers proposed a new ordered tetragonal structure as the first metastable phase to form in a series of transformations from quenched-in B2 to the equilibrium phase. They describe this new phase as a ''DO 3 like tetragonal structure'' with a composition Ti 5 Al 2 Nb, and lattice parameters, a = 0.65 nm and c/a ≅ 1.02. Their unit cell is constituted by 8 bcc unit cells, and the atomic coordinates of their structure are given in Table 1 on this basis. The symmetry of this structure is P4/mm. Though it is not the smallest possible unit cell for the structure, comparison with other bcc binary derivative structures is easily possible on this basis. The atomic coordinates for the latter, for a ternary composition Ti 2 AlNb, are also given. They note that the site occupation for the Hsiung et al. structure is quite distinct from that for a ternary DO 3 phase or any of the other possible bcc derivative structures (neglecting 2 possibilities with 128 or 432 atoms per unit cell(8) and interstitial ordering)

Models and experimental results from the wide aperture Nb-Ti magnets for the LHC upgrade

CERN Document Server

Kirby, G.; Bajko, M.; Charrondiere, M.; Bourcey, N.; Datskov, V.I.; Fessia, P.; Feuvrier, J.; Galbraith, P.; Tabares, A. Garcia; Garcia-Perez, J.; Granieri, P.; Hagen, P.; Lorin, C.; Perez, J.C.; Russenschuck, S.; Sahner, T.; Segreti, M.; Todesco, E.; Willering, G.

2013-01-01

MQXC is a Nb-Ti quadrupole designed to meet the accelerator quality requirements needed for the phase-1 LHC upgrade, now superseded by the high luminosity upgrade foreseen in 2021. The 2-m-long model magnet was tested at room temperature and 1.9 K. The technology developed for this magnet is relevant for other magnets currently under development for the high-luminosity upgrade, namely D1 (at KEK) and the large aperture twin quadrupole Q4 (at CEA). In this paper we present MQXC test results, some of the specialized heat extraction features, spot heaters, temperature sensor mounting and voltage tap development for the special open cable insulation. We look at some problem solving with noisy signals, give an overview of electrical testing, look at how we calculate the coil resistance during at quench and show that the heaters are not working We describe the quench signals and its timing, the development of the quench heaters and give an explanation of an Excel quench calculation and its comparison including the ...

Effect of non-uniform current distribution on the stability in Nb-Ti cable-in-conduit superconducting conductor

International Nuclear Information System (INIS)

Wadayama, Y.; Koizumi, N.; Takahashi, Y.; Matsui, K.; Tsuji, H.; Shimamoto, S.

1996-01-01

30kA-NbTi Demo Poloidal Coil (DPC-U) exhibited instability such as the conductor quenches at 40% of the rated current which is still much smaller than the expected conductor critical current. It was found that this instability was caused by the non-uniform current distribution in the DPC-U conductor whose strands were insulated from each other. To investigate the instability of the DPC-U conductor, a stability experiment of a subsize conductor consisting of 27 strands was performed and the effect of the current imbalance on the stability was investigated. The current imbalance was forcibly established in the conductor using two current sources in this experiment. The experimental results indicate that the stability margin decreases as the current imbalance becomes larger and that the stability margin of the conductor is governed by the stability of the strand with the highest current in the conductor. Also, it is confirmed from the experimental results that the instability of DPC-U has to be attributed to the current imbalance in the conductor

Microscope Raman scattering and X-ray diffraction study of near-stoichiometric Ti:LiNbO3 waveguides

International Nuclear Information System (INIS)

Zhang, De-Long; Siu, G.G.; Pun, E.Y.B.

2005-01-01

The crystalline phase within guiding layers of near-stoichiometric strip and planar Ti:LiNbO 3 wave-guides, prepared by the method of simultaneous work of vapour transport equilibration (VTE) treatment and indiffusion of Ti film, was studied by combined confocal microscope Raman scattering and X-ray powder diffraction. The results show that the strip and planar waveguide layers still retain the LiNbO 3 phase and no other non-LiNbO 3 phases can be identified within the guiding layer. Li/Nb ratios inside and outside the strip and planar waveguide layers were determined from the microscope Raman scattering results and compared to those obtained from the measured optical absorption edge. It is shown that the Li/Nb ratios are homogeneous within the waveguide layer and are close inside and outside the waveguide layer. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Bone bonding bioactivity of Ti metal and Ti-Zr-Nb-Ta alloys with Ca ions incorporated on their surfaces by simple chemical and heat treatments.

Science.gov (United States)

Fukuda, A; Takemoto, M; Saito, T; Fujibayashi, S; Neo, M; Yamaguchi, S; Kizuki, T; Matsushita, T; Niinomi, M; Kokubo, T; Nakamura, T

2011-03-01

Ti15Zr4Nb4Ta and Ti29Nb13Ta4.6Zr, which do not contain the potentially cytotoxic elements V and Al, represent a new generation of alloys with improved corrosion resistance, mechanical properties, and cytocompatibility. Recently it has become possible for the apatite forming ability of these alloys to be ascertained by treatment with alkali, CaCl2, heat, and water (ACaHW). In order to confirm the actual in vivo bioactivity of commercially pure titanium (cp-Ti) and these alloys after subjecting them to ACaHW treatment at different temperatures, the bone bonding strength of implants made from these materials was evaluated. The failure load between implant and bone was measured for treated and untreated plates at 4, 8, 16, and 26 weeks after implantation in rabbit tibia. The untreated implants showed almost no bonding, whereas all treated implants showed successful bonding by 4 weeks, and the failure load subsequently increased with time. This suggests that a simple and economical ACaHW treatment could successfully be used to impart bone bonding bioactivity to Ti metal and Ti-Zr-Nb-Ta alloys in vivo. In particular, implants heat treated at 700 °C exhibited significantly greater bone bonding strength, as well as augmented in vitro apatite formation, in comparison with those treated at 600 °C. Thus, with this improved bioactive treatment process these advantageous Ti-Zr-Nb-Ta alloys can serve as useful candidates for orthopedic devices. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Fabrication of Intermetallic Titanium Alloy Based on Ti2AlNb by Rapid Quenching of Melt

Science.gov (United States)

Senkevich, K. S.; Serov, M. M.; Umarova, O. Z.

2017-11-01

The possibility of fabrication of rapidly quenched fibers from alloy Ti - 22Al - 27Nb by extracting a hanging melt drop is studied. The special features of the production of electrodes for spraying the fibers by sintering mechanically alloyed powdered components of the alloy, i.e., titanium hydride, niobium, and aluminum dust, are studied. The rapidly quenched fibers with homogeneous phase composition and fine-grained structure produced from alloy Ti - 22Al - 27Nb are suitable for manufacturing compact semiproducts by hot pressing.

Peculiarities of α- and ω-phase precipitations in cold-deformed Ti-Nb alloys

International Nuclear Information System (INIS)

Kadykova, G.N.

1978-01-01

The peculiar features of the depositions of ω and α-phases have been examined, the depositions being evolved under the following conditions: holding in vacuum of 10 -5 mm Hg at the temperature of about 250 to 450 deg C, of an alloy containing 30% Ti, 35% Nb, and 7.5% Zr, which was previously subjected to quenching and cold deformation up to the thickness of about 0.1 mm. The structure of the alloys was examined by resorting to the X-ray, metallographic, and electron-microscopic analysis methods. The microhardness was measured. It is the cold deformation that promotes intensely the formation of α-phase in the ageing of Ti-Nb alloys. In this case, the formation of ω-phase is suppressed. At the initial stages of decomposition, the equiaxial particles of α phase are formed in titanium alloys containing about 30 to 35% Nb and up to 7.5% Zr: then the acicular α particles are formed in less distorted areas of β-matrix. A variation in their dimensions depending on the treatment conditions is shown. An increase in hardness of the examined cold-strained alloys in ageing, within the temperature range of up to about 350 deg C, is attributed to the formation of α+β structure. On cold straining and ageing, it proves to be possible to create β+ω+α structure in Ti-Nb alloys. For this purpose, before starting the cold straining, it will be necessary to obtain the structure containing a considerable proportion of ω-phase

Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

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Hidetatsu Tanaka

Full Text Available Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

Regulation of depletion layer width in Pb(Zr,Ti)O3/Nb:SrTiO3 heterostructures

Science.gov (United States)

Bai, Yu; Jie Wang, Zhan; Cui, Jian Zhong; Zhang, Zhi Dong

2018-05-01

Improving the tunability of depletion layer width (DLW) in ferroelectric/semiconductor heterostructures is important for the performance of some devices. In this work, 200-nm-thick Pb(Zr0.4Ti0.6)O3 (PZT) films were deposited on different Nb-doped SrTiO3 (NSTO) substrates, and the tunability of DLW at PZT/NSTO interfaces were studied. Our results showed that the maximum tunability of the DLW was achieved at the NSTO substrate with 0.5 wt% Nb. On the basis of the modified capacitance model and the ferroelectric semiconductor theory, we suggest that the tunability of the DLW in PZT/NSTO heterostructures can be attributed to a delicate balance of the depletion layer charge and the ferroelectric polarization charge. Therefore, the performance of some devices related to the tunability of DLW in ferroelectric/semiconductor heterostructures can be improved by modulating the doping concentration in semiconducting electrode materials.

Critical current and electric transport properties of superconducting epitaxial Nb(Ti)N submicron structures

Science.gov (United States)

Klimov, A.; Słysz, W.; Guziewicz, M.; Kolkovsky, V.; Wegrzecki, M.; Bar, J.; Marchewka, M.; Seredyński, B.

2016-12-01

Critical current and current-voltage characteristics of epitaxial Nb(Ti)N submicron ultrathin structures were measured as function of temperature. For 700-nm-wide bridge we found current-driven vortex de-pinning at low temperatures and thermally activated flux flow closer to the transition temperature, as the limiting factors for the critical current density. For 100-nm-wide meander we observed combination of phase-slip activation and vortex-anti-vortex pair (VAP) thermal excitation. Our Nb(Ti)N meander structure demonstrates high de-pairing critical current densities 107 A/cm2 at low temperatures, but the critical currents are much smaller due to presence of the local constrictions.

Porous Nb-Ti based alloy produced from plasma spheroidized powder

Science.gov (United States)

Li, Qijun; Zhang, Lin; Wei, Dongbin; Ren, Shubin; Qu, Xuanhui

Spherical Nb-Ti based alloy powder was prepared by the combination of plasma spheroidization and mechanical alloying. Phase constituents, microstructure and surface state of the powder, and pore characteristics of the resulting porous alloy were investigated. The results show that the undissolved W and V in the mechanically alloyed powder is fully alloyed after spheroidization, and single β phase is achieved. Particle size of the spheroidized powder is in the range of 20-110 μm. With the decrease of particle size, a transformation from typical dendrite solidification structure to fine cell microstructure occurs. The surface of the spheroidized powder is coated by a layer of oxides consisting mainly of TiO2 and Nb2O5. Probabilities of sinter-neck formation and particle coalescence increases with increasing sintering temperature. Porous skeleton with relatively homogeneous pore distribution and open pore channel is formed after vacuum sintering at 1700 °C, and the porosity is 32%. The sintering kinetic analysis indicates that grain boundary diffusion is the primary mass transport mechanism during sintering process.

Texture Evolution in a Ti-Ta-Nb Alloy Processed by Severe Plastic Deformation

Science.gov (United States)

Cojocaru, Vasile-Danut; Raducanu, Doina; Gloriant, Thierry; Cinca, Ion

2012-05-01

Titanium alloys are extensively used in a variety of applications because of their good mechanical properties, high biocompatibility, and corrosion resistance. Recently, β-type Ti alloys containing Ta and Nb have received much attention because they feature not only high specific strength but also biocorrosion resistance, no allergic problems, and biocompatibility. A Ti-25Ta-25Nb β-type titanium alloy was subjected to severe plastic deformation (SPD) processing by accumulative roll bonding and investigated with the aim to observe the texture developed during SPD processing. Texture data expressed by pole figures, inverse pole figures, and orientation distribution functions for the (110), (200), and (211) β-Ti peaks were obtained by XRD investigations. The results showed that it is possible to obtain high-intensity share texture modes ({001}) and well-developed α and γ-fibers; the most important fiber is the α-fiber ({001} to {114} to {112} ). High-intensity texture along certain crystallographic directions represents a way to obtain materials with high anisotropic properties.

Proximity effect depression of the critical temperature in two-phase Nb-Ti superconductors

International Nuclear Information System (INIS)

Meingast, C.; Daeumling, M.; Lee, P.J.; Larbalestier, D.C.

1987-01-01

The superconducting critical temperature of high critical current density Nb-Ti composites has been measured at various stages in the critical current optimization process. This process involves heat treatment steps which cause precipitation of normal α-Ti and make the matrix more Nb rich. T/sub c/ rises from 9.1 to 9.5 K during this stage. The final optimization stage involves extensive wire drawing during which the α-Ti precipitates are reduced to less than a coherence length in thickness. This does not result in a reduction in J/sub c/ but T/sub c/ is found to fall from 9.44 to 8.7 K during this step. The depression of T/sub c/ is found to be in fair agreement with the predicted proximity effect suppression of T/sub c/. Wires of optimum transport critical current density are seen to have T/sub c/ of around 9 K

Corrosion behavior of Ti-13Nb-13Zr alloy used as a biomaterial

International Nuclear Information System (INIS)

Niemeyer, T.C.; Grandini, C.R.; Pinto, L.M.C.; Angelo, A.C.D.; Schneider, S.G.

2009-01-01

Titanium alloys were developed as an alternative to stainless steels and have been extensively used as biomaterials ever since. One of these alloys is Ti-13Nb-13Zr (TNZ), a near-beta phase alloy containing elements with excellent biocompatibility. The main advantage of the TNZ alloy, compared to other titanium alloys, such as Ti-6Al-4V and Ti-6Al-7Nb, widely used as biomaterials, is its low elasticity modulus, closer to that of bone, and the absence of aluminum and vanadium, which have been reported to cause long-term adverse effects. In this paper, the corrosion and electrochemical behavior of TNZ alloy (as cast and after oxygen charge) was studied in a PBS solution. The results showed that, with the oxygen load, there is a significant reduction of the anodic current in almost the whole potential spam explored in this work, meaning that the corrosion rate decreases when the doping is performed.

Construction and Qualification of the Pre-Series MQM Superconducting Quadrupoles for the LHC Insertions

CERN Document Server

Ostojic, R; Lucas, J; Venturini-Delsolaro, W; Landgrebe, D

2004-01-01

The LHC insertions will be equipped with individually powered MQM superconducting quadrupoles, produced in three versions with magnetic lengths of 2.4 m, 3.4 m, and 4.8 m. The quadrupoles feature a 56 mm aperture coil, designed on the basis of an 8.8 mm wide Rutherford-type NbTi cable for a nominal gradient of 200 T/m at 1.9 K and 5390 A. A total of 96 quadrupoles are in production in Tesla Engineering, UK. In this report we describe the construction of the pre-series MQM quadrupoles and present the results of the qualification tests.

Defect and electrical transport properties of Nb-doped SrTiO₃

DEFF Research Database (Denmark)

Blennow Tullmar, Peter; Hagen, Anke; Kammer Hansen, Kent

2008-01-01

analyzed with SEM, XRD, TGA, and XANES. The electrical conductivity of Nb-doped strontium titanate (Sr0.94Ti0.9Nb0.1O3 - sintered in 9% H-2/N-2 at 1400 degrees C for 12 h) decreased with increasing temperature and showed a phonon scattering conduction mechanism with (sigma>120 S/cm at 1000 degrees C (in 9...

R&D for a single-layer Nb$_{3}$Sn common coil dipole using the react-and-wind fabrication technique

CERN Document Server

Ambrosio, G; Barzi, E; Bauer, P; Chichili, D R; Ewald, K D; Fehér, S; Imbasciati, L; Kashikhin, V V; Limon, P J; Litvinenko, L; Novitski, I; Rey, J M; Scanlan, R M; Yadav, S; Yamada, R; Zlobin, A V

2002-01-01

A dipole magnet based on the common coil design, using prereacted Nb /sub 3/Sn superconductor, is under development at Fermilab, for a future Very Large Hadron Collider. This magnet has some innovative design and technological features such as single layer coils, a 22 mm wide 60-strand Rutherford type cable and stainless steel collars reinforced by horizontal bridges inserted between coil blocks. Both left and right coils are wound simultaneously into the collar structure and then impregnated with epoxy. In order to optimize the design and fabrication techniques an R&D program is underway. The production of cables with the required characteristics was shown possible. Collar laminations were produced, assembled and tested in order to check the effectiveness of the bridges and the validity of the mechanical design. A mechanical model consisting in a 165 mm long section of the magnet straight section was assembled and tested. This paper summarizes the status of the program, and reports the results of fabrica...

The effect of Zr content on the microstructure, mechanical properties and cell attachment of Ti-35Nb-xZr alloys

International Nuclear Information System (INIS)

Ning Congqin; Zhai Wanyin; Chen Lei; Ding Dongyan; Dai Kerong

2010-01-01

β-type low elastic modulus alloys of the Ti-Nb-Zr system have recently attracted much attention for both orthopedic and dental applications. In the present study, meta-stable β alloys of Ti-35Nb-xZr with different Zr contents were developed. The effect of Zr content on the microstructure, mechanical properties and cell attachment was investigated. It was found that the addition of Zr improved the tensile strength and elongation of Ti-35Nb-xZr alloys, and simultaneously reduced the elastic modulus. Moreover, the Zr element helped to stabilize the β phase. Cell culture work indicated that the addition of Zr enhanced the attachment and spreading of bone marrow stem cells. Cell attachment and spreading on the surface of titanium alloys were dominated not only by the wettability but also by the inherent biocompatibility of alloying elements. The peak-aged alloy with 5 wt% Zr had a highest tensile strength of 874 MPa, while its elastic modulus was only 65 GPa, presenting a much higher strength/modulus ratio than Ti-6Al-4V. The Ti-35Nb-5Zr alloy exhibited a great potential for orthopedic and dental applications.

Direction-dependent RBS channelling studies in ion implanted LiNbO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Wendler, E., E-mail: elke.wendler@uni-jena.de; Becker, G.; Rensberg, J.; Schmidt, E.; Wolf, S.; Wesch, W.

2016-07-15

Damage formation in ion implanted LiNbO{sub 3} was studied by Rutherford backscattering spectrometry (RBS) along various directions of the LiNbO{sub 3} crystal. From the results obtained it can be unambiguously concluded that Nb atoms being displaced during ion implantation preferably occupy the free octahedron sites of the LiNbO{sub 3} lattice structure and most likely also form Nb{sub Li} antisite defects.

Transmission electron microscopy of Ti-12Mo-13Nb Alloy aged after heat forging

International Nuclear Information System (INIS)

Oliveira, Nathalia Rodrigues; Baldan, Renato; Gabriel, Sinara Borborema

2014-01-01

Metastable β-Ti alloys possess mechanical properties, in particular a elastic modulus that depends not only on its composition but also the applied thermomechanical treatments. These alloys require high mechanical strength and a low Young’s modulus to avoid stress shielding. Preliminary studies on the development of Ti- 13Nb-12Mo alloy showed than the better properties were obtained at aged at 500 ° C / 24 h after cold forging , whose microstructure consisted of bimodal α phase in the β matrix. In this work, Ti-12Mo-13Nb alloy was heat forged and aged at 500 deg C for 24h and the microstructure was analyzed by employing X-ray diffraction and transmission electron microscopy. According to the results, while the cold forging resulted in bimodal α phase in the β matrix, hot forging resulted in a fine and homogeneous α phase in the β matrix. (author)

Enhancement of wear and corrosion resistance of low modulus β-type Zr-20Nb-xTi (x=0, 3) dental alloys through thermal oxidation treatment.

Science.gov (United States)

Zhang, Jianfeng; Gan, Xiaxia; Tang, Hongqun; Zhan, Yongzhong

2017-07-01

In order to obtain material with low elastic modulus, good abrasion resistance and high corrosion stability as screw for dental implant, the biomedical Zr-20Nb and Zr-20Nb-3Ti alloy with low elastic modulus were thermal oxidized respectively at 700°C for 1h and 600°C for 1.25h to obtain the compact oxidized layer to improve its wear resistance and corrosion resistance. The results show that smooth compact oxidized layer (composed of monoclinic ZrO 2 , tetragonal ZrO 2 and 6ZrO 2 -Nb 2 O 5 ) with 22.6μm-43.5μm thickness and 1252-1306HV hardness can be in-situ formed on the surface of the Zr-20Nb-xTi (x=0, 3). The adhesion of oxidized layers to the substrates is determined to be 58.35-66.25N. The oxidized Zr-20Nb-xTi alloys reveal great improvement of the pitting corrosion resistance in comparison with the un-oxidized alloys. In addition, the oxidized Zr-20Nb-3Ti exhibits sharply reduction of the corrosion rates and the oxidized Zr-20Nb shows higher corrosion rates than un-oxidized alloys, which is relevant with the content of the t-ZrO 2 . Wear test in artificial saliva demonstrates that the wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) are superior to pure Ti. All of the un-oxidized Zr-20Nb-xTi (x=0, 3) alloys suffer from serious adhesive wear due to its high plasticity. Because of the protection from compact oxide layer with high adhesion and high hardness, the coefficients of friction and wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) alloys decrease 50% and 95%, respectively. The defects on the oxidized Zr-20Nb have a negative effect on the friction and wear properties. In addition, after the thermal oxidation, compression test show that elastic modulus and strength of Zr-20Nb-xTi (x=0, 3) increase slightly with plastic deformation after 40% of transformation. Furthermore, stripping of the oxidized layer from the alloy matrix did not occur during the whole experiments. As the surface oxidized Zr-20Nb-3Ti alloy has a combination of excellent performance

Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

Science.gov (United States)

Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

2016-01-01

Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

M₅Si₃(M=Ti, Nb, Mo) Based Transition-Metal Silicides for High Temperature Applications

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhihong [Iowa State Univ., Ames, IA (United States)

2007-01-01

Transition metal silicides are being considered for future engine turbine components at temperatures up to 1600 C. Although significant improvement in high temperature strength, room temperature fracture toughness has been realized in the past decade, further improvement in oxidation resistance is needed. Oxidation mechanism of Ti₅Si₃-based alloys was investigated. Oxidation behavior of Ti₅Si₃-based alloy strongly depends on the atmosphere. Presence of Nitrogen alters the oxidation behavior of Ti₅Si₃ by nucleation and growth of nitride subscale. Ti₅Si_3.2and Ti₅Si₃C_0.5 alloys exhibited an excellent oxidation resistance in nitrogen bearing atmosphere due to limited dissolution of nitrogen and increased Si/Ti activity ratio. MoSi₂ coating developed by pack cementation to protect Mo-based Mo-Si-B composites was found to be effective up to 1500 C. Shifting coating composition to T1+T2+Mo₃Si region showed the possibility to extend the coating lifetime above 1500 C by more than ten times via formation of slow growing Mo₃Si or T2 interlayer without sacrificing the oxidation resistance of the coating. The phase equilibria in the Nb-rich portion of Nb-B system has been evaluated experimentally using metallographic analysis and differential thermal analyzer (DTA). It was shown that Nb_ss (solid solution) and NbB are the only two primary phases in the 0-40 at.% B composition range, and the eutectic reaction L {leftrightarrow} Nb_SS + NbB was determined to occur at 2104 ± 5 C by DTA.

Surface energy effects on the stability of anatase and rutile nanocrystals: A predictive diagram for Nb_2O_5-doped-TiO_2

International Nuclear Information System (INIS)

Silva, Andre Luiz da; Hotza, Dachamir; Castro, Ricardo H.R.

2017-01-01

Highlights: • Anatase-rutile phase transition diagram was built for nano Nb_2O_5-doped-TiO_2. • Nb_2O_5-doping postpones the anatase-to-rutile transition. • The stability crossover for TiO_2 was 17.3 nm, for 2 mol% Nb_2O_5-doped-TiO_2 ∼30 nm. • The surface energy for Nb_2O_5-doped-TiO_2 decreases systematically with Nb concentration. - Abstract: Titanium dioxide nanoparticles are widely used for photocatalysis, and the relative fraction of titanium dioxide polymorph, i.e. anatase, rutile, or brookite, significantly affects the final performance. Even though conventional phase diagrams indicate a higher stability for the rutile polymorph, it is well established that nanosizes benefit the anatase phase due to its smaller surface energy. However, doping elements are expected to change this behavior, once changes in both surface and bulk energies may occur. Nb_2O_5 is commonly added to TiO_2 to allow property control. However, the effect of niobium on the relative stability of anatase and rutile phases is not well understood from the thermodynamic point of view. The objective of this work was to build a new predictive nanoscale phase diagram for Nb_2O_5-doped TiO_2. Water adsorption microcalorimetry and high temperature oxide melt solution were used to obtain the surface and bulk enthalpies. The phase diagram obtained shows the stable titania polymorph as a function of the composition and size.

The effect of aging on the critical current density in superconducting Nb-Ti-Zr alloys

International Nuclear Information System (INIS)

Ishida, Fumihiko; Doi, Toshio

1979-01-01

The effect of aging temperature, cold-reduction prior to aging, O 2 content and composition on the variation in the critical current density, J sub(c), by isothermal aging was investigated in heavily cold-worked Nb-Ti-Zr alloys on the Nb-Ti side. The results are summarized as follows: (1) When these alloys are aged isothermally at temperatures from 350 to 500 0 C, J sub(c) increases initially, reaches a maximum value and then decreases. Increase in J sub(c) of three orders of magnitude is possible as a result of aging. (2) The maximum value of J sub(c) on the isothermal aging curve becomes higher at a lower aging temperature, at a less cold-reduction prior to aging or with a higher O 2 content. (3) The J sub(c) of aged alloy becomes a maximum in composition containing 35 at%Nb, 60 to 65 at%Ti and less than 5 at%Zr. (4) The maximum value of J sub(c) was obtained for Nb-60.0 at%Ti-5.0 at%Zr alloy containing 1200 wt ppm O 2 , aged at 350 0 C for 330 h after 98.44% cold-reduction. The values of J sub(c) at 4.2 K were 2.4 x 10 9 A/m 2 at 5.0 T, 1.1 x 10 9 A/m 2 at 7.0 T and 3.0 x 10 8 A/m 2 at 9.0 T, respectively. The upper critical field of this specimen was 11.3 T at 4.2 K and its critical temperature was 8.6 K. (author)

Castability of Ti-6Al-7Nb alloy for dental casting

OpenAIRE

Wang, Tie Jun; 小林, 郁夫; 土居, 壽; 米山, 隆之

1999-01-01

Castability of Ti-6Al-7Nb alloy, CP Ti, and Co-Cr alloy was examined for mesh type and plate type specimens. The casting was carried out with a pressure type casting machine and commercial molding material. The castability of the mesh type specimen was evaluated in terms of the number of cast segments (castability index), and that of the plate type was evaluated by the area of the speci­men (casting rate). X-ray images processed by a digital imaging technique were used to identify the casting...

Understanding the role of carbon atoms on microstructure and phase transformation of high Nb containing TiAl alloys

Energy Technology Data Exchange (ETDEWEB)

Wu, Zeen; Hu, Rui; Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Zhang, Fan; Kou, Hongchao; Li, Jinshan

2017-02-15

The microstructure and solidification behavior of high Nb containing TiAl alloys with the composition of Ti-46Al-8Nb-xC (x = 0.1, 0.7, 1.4, 2.5 at.%) prepared by arc-melting method have been investigated in this work. The results give evidence that the addition of carbon changes the solidification behavior from solidification via the β phase to the peritectic solidification. And carbon in solid solution enriches in the α{sub 2} phase and increases the microhardness. As the carbon content increases to 1.4 at.%, plate-shape morphology carbides Ti{sub 2}AlC (H phase) precipitate from the TiAl matrix which leads to the refinement microstructure. By aging at 1173 K for 24 h after quenching treatment, fine needle-like and granular shape Ti{sub 3}AlC (P phase) carbides are observed in the matrix of Ti-46Al-8Nb-2.5C alloy, which distribute along the lamellar structure or around the plate-shape Ti{sub 2}AlC. Transmission electron microscope observation shows that the Ti{sub 3}AlC carbides precipitate at dislocations. The phase transformation in-situ observations indicate that the Ti{sub 2}AlC carbides partly precipitate during the solid state phase transformation process. - Highlights: •Carbon changes the solidification behavior from β phase to peritectic solidification. •Dislocations in solution treated γ phase act as nucleation sites of Ti{sub 3}AlC precipitations. •Ti{sub 3}AlC precipitates as fine needle-like or granular shape in the solution treated matrix. •Ti{sub 2}AlC carbides precipitate during the solid state phase transformation process.

Development of Nb3Sn cabled conductor by external diffusion process and the effect of strain on the critical current

International Nuclear Information System (INIS)

Pasztor, G.; Ekin, J.W.

1984-01-01

The planned extension of the High Field Test Facility SULTAN at SIN to provide 12 T operation in a 60 cm bore has led to an increased involvements on the part of SIN in the development of reliable A15 multifilamentary conductors. It is the purpose of this paper to describe the development of stranded Nb 3 Sn conductors using the external diffusion technique. Although not fully optimized, the primary cables have high overall critical current densities. Problems associated with the diffusion of the tin into the copper matrix, such as tin coalescence and development of Kirkendall porosity were successfully solved using small diameter wires and by appropriate diffusion and reaction heat treatment conditions. The elastic strain sensitivity of the critical current of a previously developed cable was comparable to that of bronze processed monolithic Nb 3 Sn, while the irreversible strain limit of 1.2% was significantly higher, On the other hand a longer current transfer length (about 4 times that of bronze processed monolithic conductors) was found

Synthesis and photocatalytic activity of hydrated layered perovskite K2-xLa2Ti3-xNb xO10 (0 ≤ x ≤ 1) and protonated derivatives

International Nuclear Information System (INIS)

Huang Yunfang; Wu Jihuai; Wei Yuelin; Hao Sancun; Huang Miaoliang; Lin Jianming

2007-01-01

A series of photocatalytic intercalated materials K 2-x La 2 Ti 3-x Nb x O 10 (0 ≤ x ≤ 1) and a series of its protonated derivatives H 2-x La 2 Ti 3-x Nb x O 10 were prepared by solid-state reaction and ion-exchange reaction. The photocatalytic activities of samples were evaluated using methanol as electron donor under UV irradiation. All H 2-x La 2 Ti 3-x Nb x O 10 samples possessed approximately twofold higher photocatalytic activity than the corresponding K 2-x La 2 Ti 3-x Nb x O 10 . This difference was most pronounced for the photocatalyst H 1.9 La 2 Ti 2.9 Nb 0.1 O 10 which showed the highest activity: 22 μmol H 2 /catalyst (g) for 5 h, more than three times the activity of K 1.9 La 2 Ti 2.9 Nb 0.1 O 10

Analysis of Electrical Coupling Parameters in Superconducting Cables

CERN Document Server

Bottura, L; Rosso, C

2003-01-01

The analysis of current distribution and redistribution in superconducting cables requires the knowledge of the electric coupling among strands, and in particular the interstrand resistance and inductance values. In practice both parameters can have wide variations in cables commonly used such as Rutherford cables for accelerators or Cable-in-Conduits for fusion and SMES magnets. In this paper we describe a model of a multi-stage twisted cable with arbitrary geometry that can be used to study the range of interstrand resistances and inductances that is associated with variations of geometry. These variations can be due to cabling or compaction effects. To describe the variations from the nominal geometry we have adopted a cable model that resembles to the physical process of cabling and compaction. The inductance calculation part of the model is validated by comparison to semi-analytical results, showing excellent accuracy and execution speed.

Processing and properties of Nb-Ti-based alloys

International Nuclear Information System (INIS)

Sikka, V.K.; Viswanathan, S.

1992-01-01

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep test at 650 C and 172 MPa was conducted on the base alloy which contained 40Nb-40Ti-10Al-10Cr. A second alloy was modified with 0.11 at. % carbon and 0.07 at. % yttrium. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1,100 C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400, 600, 700, 800, 900, and 1,000 C, and for the modified alloy at room temperature, 400, 600, 700, and 800 C. Oxidation tests on the base alloy and modified alloy, as measured by weight change, were carried out at 600, 700, 800, and 900 C. Both the base alloy and the modified alloy were extremely ductile and were cold rolled to the final sheet thickness of 0.8 mm without an intermediate anneal. The modified alloy exhibited some edge cracking during cold during cold rolling. Both alloys recrystallized at the end of a 0.5-h annealing treatment. The alloys exhibited moderate strength and oxidation resistance below 600 C, similar to the results of alloys reported in the literature

Multi-level resistive switching behaviors and retention characteristics in ZnO/Nb:SrTiO3 heterojunction

Science.gov (United States)

Ren, Yong; Li, Jiachen; Zhang, Weifeng; Jia, Caihong

2017-10-01

Epitaxial ZnO thin films were grown on SrTiO3:Nb (NSTO) substrates by rf magnetron sputtering method. The multi-level resistance states were observed by applying different amplitudes and/or polarities of voltage pulses, which is supposed to be related to the drift of oxygen vacancies. Furthermore, the decay of retention is also corresponding to the migration of oxygen vacancies. The retention and cycle stability implies that the ZnO/Nb:SrTiO3 heterojunctions are promising for high density memory application.

Phase evolution in Al-Ni-(Ti, Nb, Zr) powder blends by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Samanta, A. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur (India); Manna, I. [Metallurgical and Materials Engineering Department, I.I.T., Kharagpur 721302 (India); Chattopadhyay, P.P. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur (India)], E-mail: c.partha@mailcity.com

2007-08-25

Mechanical alloying of Al-rich Al-Ni-ETM (ETM = Ti, Nb, Zr) elemental powder blends by planetary ball milling yielded amorphous and/or nanocrystalline products after ball milling for suitable duration. Powder samples collected at different stages of ball milling have been examined by X-ray diffraction, differential scanning caloremetry and high-resolution transmission electron microscopy to examine the solid-state phase evolution. Powder blends having nominal composition of Al{sub 80}Ni{sub 10}Ti{sub 10} and Al{sub 80}Ni{sub 10}Nb{sub 10} yielded predominantly amorphous products, while the other alloys formed composite microstructures comprising nanaocrystalline and amorphous solid solutions. The amorphous Al{sub 80}Ni{sub 10}Ti{sub 10} alloy was mixed with different amounts of Al powder, and subjected to warm rolling after consolidation within the Al-cans with or without intermediate annealing for 10 min at 500 K to obtain sheet of 2.5 mm thickness. Notable improvement in mechanical properties has been achieved for the composite sheets in comparison to the pure Al.

Influence of Ta and Ti Doping on the High Field Performance of (Nb, Ta, Ti)3Sn Multifilamentary Wires based on Osprey Bronze with High Tin Content

International Nuclear Information System (INIS)

Abaecherli, V; Uglietti, D; Lezza, P; Seeber, B; Fluekiger, R; Cantoni, M; Buffat, P-A

2006-01-01

Ta and Ti are the most widely used additions for technical Nb 3 Sn multifilamentary superconductors. These elements are known to influence grain growth, grain morphology and chemical composition in the A15 layer, hence the current carrying properties of the wires over a wide magnetic field range. So far only few studies tried to compare systematically Ta and Ti doped and undoped Nb 3 Sn wires in the frame of the same work, down to a nanometric scale. We present an investigation on several multifilamentary (Nb, Ta, Ti) 3 Sn bronze route wires, fabricated at a laboratory scale, with various amounts of additives. The wires consist of fine filaments embedded in a Cu-Sn or Cu-Sn-Ti Osprey bronze with > 15 wt.% Sn and an external Cu stabilization. Microstructural observations are compared with the results of J c and n values measured up to 21 T at 4.2 and 2.2 K, and for longitudinal strains up to 0.5%. Non-Cu J c values up to 300 Amm -2 and n values up to 50 at 17 T and 4.2 K show clearly that wires with Ti addition to the bronze have a better performance with respect to wires with Ti additions to the filaments

Growth (AlCrNbSiTiV)N thin films on the interrupted turning and properties using DCMS and HIPIMS system

Science.gov (United States)

Chang, Kai-Sheng; Chen, Kuan-Ta; Hsu, Chun-Yao; Hong, Po-Da

2018-05-01

This paper determines the optimal settings in the deposition parameters for (AlCrNbSiTiV)N high-entropy alloy (HEAs) nitride films that are deposited on CBN cutting tools and glass substrates. We use direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HIPIMS), with Ar plasma and N2 reactive gases. Experiments with the grey-Taguchi method are conducted to determine the effect of deposition parameters (deposition time, substrate DC bias, DC power and substrate temperature) on interrupted turning 50CrMo4 steel machining and the films' structural properties. Experimental result shows that the multiple performance characteristics for these (AlCrNbSiTiV)N HEAs film coatings can be improved using the grey-Taguchi method. As can be seen, the coated film is homogeneous, very compact and exhibits perfect adherence to the substrate. The distribution of elements is homogeneous through the depth of the (AlCrNbSiTiV)N film, as measured by an auger electron nanoscope. After interrupted turning with an (AlCrNbSiTiV)N film coated tool, we obtain much longer tool life than when using uncoated tools. The correlation of these results with microstructure analysis and tool life indicates that HIPIMS discharge induced a higher (AlCrNbSiTiV)N film density, a smoother surface structure and a higher hardness surface.