Impurity stabilized<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi><mml:mi /><mml:mn>15</mml:mn></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Nb</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Nb - a new superconductor

Stewart, G. R.; Newkirk, L. R.; Valencia, F.A.

doi:10.1103/physrevb.21.5055

Cited by 37 publications

(18 citation statements)

References 14 publications

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“…Niobium has the bcc structure, which is also the structure of the Nb solid solution in Nb-silicide-based alloys [14]. Niobium can form a metastable A15-Nb 3 Nb structure with 0.5246 nm lattice parameter [40]. The lattice parameter of the stoichiometric A15-Nb 3 Sn is 0.529 nm [41].…”

Section: Microstructuresmentioning

confidence: 99%

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

2020

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In this paper two Nb-silicide-based alloys with nominal compositions (at.%) Nb-12Ti-18Si-6Ta-2.5W-1Hf-2Sn-2Ge (JZ1) and Nb-12Ti-18Si-6Ta-2.5W-1Hf-5Sn-5Ge (JZ2) were studied. The alloys were designed using the alloy design methodology NICE to meet specific research objectives. The cast microstructures of both alloys were sensitive to solidification conditions. There was macro-segregation of Si in JZ1 and JZ2. In both alloys the βNb5Si3 was the primary phase and the Nbss was stable. The A15-Nb3X (X = Ge,Si,Sn) was stable only in JZ2. The Nbss+βNb5Si3 eutectic in both alloys was not stable as was the Nb3Si silicide that formed only in JZ1. At 800 °C both alloys followed linear oxidation kinetics and were vulnerable to pesting. At 1200 °C both alloys exhibited parabolic oxidation kinetics in the early stages and linear kinetics at longer times. The adhesion of the scale that formed on JZ2 at 1200 °C and consisted of Nb and Ti-rich oxides, silica and HfO2 was better than that of JZ1. The microstructure of JZ2 was contaminated by oxygen to a depth of about 200 μm. There was no Ge or Sn present in the scale. The substrate below the scale was richer in Ge and Sn where the NbGe2, Nb5(Si1-xGex)3, W-rich Nb5(Si1-xGex)3, and A15-Nb3X compounds (X = Ge,Si,Sn) were formed in JZ2. The better oxidation behavior of JZ2 compared with JZ1 correlated well with the decrease in VEC and increase in δ parameter values, in agreement with NICE. For both alloys the experimental data for Si macrosegregation, vol.% Nbss, chemical composition of Nbss and Nb5Si3, and weight gains at 800 and 1200 °C was compared with the calculations (predictions) of NICE. The agreement was very good. The calculated creep rates of both alloys at 1200 °C and 170 MPa were lower than that of the Ni-based superalloy CMSX-4 for the same conditions but higher than 10−7 s−1.

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Section: Microstructuresmentioning

confidence: 99%

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

2020

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“…in which the lattice parameter is extrapolated from 0.529 nm at β = 0.25 to a Nb 3 Nb value of 0.5246 nm [5] FIG. 5: Resistivity as function of atomic Sn content after Flükiger [4,32] † .…”

Section: Variations In Lattice Propertiesmentioning

confidence: 99%

“…5: Resistivity as function of atomic Sn content after Flükiger [4,32] † . The solid curve is a fit to the data according to (5). † Adapted with kind permission of R. Flükiger.…”

Section: Variations In Lattice Propertiesmentioning

confidence: 99%

“…Intermetallic Niobium-Tin is based on the superconductor Nb, which exists in a bcc Nb structure (T c ∼ = 9.2 K), or a metastable Nb 3 Nb A15 structure (T c ∼ = * Previous address: Low Temperature Division, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands 5.2 K) [4,5]. When alloyed with Sn and in thermodynamic equilibrium, it can form either Nb 1−β Sn β (about 0.18 ≤ β ≤ 0.25) or the line compounds Nb 6 Sn 5 and NbSn 2 according to the generally accepted binary phase diagram by Charlesworth et al [6] (figure 1).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A review of the properties of Nb₃Sn and their variation with A15 composition, morphology and strain state

Godeke¹

2006

Supercond. Sci. Technol.

232

213

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Significant efforts can be found throughout the literature to optimize the current carrying capacity of Nb3Sn superconducting wires. The achievable transport current density in wires depends on the A15 composition, morphology and strain state. The A15 sections in wires contain, due to compositional inhomogeneities resulting from solid state diffusion A15 formation reactions, a distribution of superconducting properties. The A15 grain size can be different from wire to wire and is also not necessarily homogeneous across the A15 regions. Strain is always present in composite wires, and the strain state changes as a result of thermal contraction differences and Lorentz forces in magnet systems. To optimize the transport properties it is thus required to identify how composition, grain size and strain state influence the superconducting properties. This is not accurately possible in inhomogeneous and spatially complex systems such as wires. This article therefore gives an overview of the available literature on simplified, well defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb3Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb3Sn is available. This article is intended to provide such an overview. It starts with a basic description of the Niobium-Tin intermetallic. After this it maps the influence of Sn content on the the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be briefly summarized. This is followed by a review on the effects of grain size and strain. The article is concluded with a summary of the main results.

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“…The sign convention is such that AEx-y> 0 indicates that Y is more stable than X. Interestingly enough, where A15 strongly competes with bcc is where bcc-based TM can be found in a metastable state with the A15 structure, by small addition of Si or Ge [11]. On the other hand, fcc is the most stable structure at high N.…”

Section: Resultsmentioning

confidence: 97%

Interplay Between Local Environment Effect and Electronic Structure Properties in Close Packed Structures

Turchi

1990

MRS Proc.

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Within a tight binding framework, the interplay between local atomic arrangement, orbital directionality and phase stability properties is discussed for a series of tetrahedrally close packed (tcp) structures. The common features which characterize the local densities of states of tcp phases can be explained by a moment analysis up to fourth order terms. On the contrary, it is shown that structural energy differences between simple and tcp crystalline structures requires the knowledge of at least the fifth order moments, a fact which has been underestimated in the past. Finally, the relative stability of various representative geometries, including the ones of simple crystalline structures is examined as a function of the number of valence electrons. INTRODUCTION and METHODOLOGY

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Impurity stabilizedA15Nb3Nb - a new superconductor

Cited by 37 publications

References 14 publications

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

A review of the properties of Nb₃Sn and their variation with A15 composition, morphology and strain state

Interplay Between Local Environment Effect and Electronic Structure Properties in Close Packed Structures

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Impurity stabilizedA15Nb3Nb - a new superconductor

Cited by 37 publications

References 14 publications

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

On the Microstructure and Properties of Nb-12Ti-18Si-6Ta-2.5W-1Hf (at.%) Silicide-Based Alloys with Ge and Sn Additions

A review of the properties of Nb3Sn and their variation with A15 composition, morphology and strain state

Interplay Between Local Environment Effect and Electronic Structure Properties in Close Packed Structures

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Product

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A review of the properties of Nb₃Sn and their variation with A15 composition, morphology and strain state