The effect of strain on the martensitic phase transition in superconducting Nb&amp;lt;inf&amp;gt;3&amp;lt;/inf&amp;gt;Sn

Hoard, R. W.; Scanlan, R.M.; Smith, G. V.; Farrell, C. E.

doi:10.1109/tmag.1981.1061126

Cited by 11 publications

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“…The intrinsic strain ε 0 corresponds roughly to the strain state of the superconducting material itself, rather than the strain applied to the superconducting composite as a whole. (The strain in the superconducting material is not exactly zero at the maximum because of three-dimensional effects (Rupp 1977, Welch 1980, Hoard et al 1981, ten Haken 1994, Markiewicz 2004), but the intrinsic strain so defined is nevertheless quite useful for characterizing the axial strain dependence of the critical current. A more detailed description of intrinsic strain and examples of its effect are reviewed in Ekin (2006, pp 434-6).)…”

Section: Strain Scaling Lawmentioning

confidence: 99%

Unified scaling law for flux pinning in practical superconductors: I. Separability postulate, raw scaling data and parameterization at moderate strains

Ekin¹

2010

Supercond. Sci. Technol.

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The unified strain-and-temperature scaling law underlies the many pinning-force-model expressions proposed to parameterize the dependence of the critical current I c on magnetic field B, temperature T and applied axial strain ε in superconductors for high-field magnet design. Increasingly, these expressions have been evaluated by use of multiparameter simultaneous fits, without the use of scaling. In this review, we reintroduce the unified scaling law on which the recent parameterizations are based, as well as the power of raw scaling data for parameter consistency, extrapolation capability and data-based model evaluation.The unified scaling law (USL) for the flux-pinning force per unit conductor length F P [≡I c (B, T, ε)B] in practical high-field superconductors is expressed bywhere K (t, ε 0 ) is a temperature-and-strain dependent prefactor. The scaling variables are: reduced magnetic field b ≡ B/B * c2 (t, ε 0 ) with B * c2 (t, ε 0 ) an effective upper critical field; reduced temperature t ≡ T /T * c (ε 0 ) with T * c (ε 0 ) an effective strain-dependent critical temperature; and intrinsic axial strain ε 0 ≡ ε − ε m defined as zero at the strain ε m , where I c is maximum. The scaling parameters p and q are constants, which is a necessary (but not sufficient) condition for scaling. The strain dependences of T * c and B * c2 are correlated as) is also designated as s(ε 0 ) in the recent literature). It is shown that, when raw scaling data are used to determine the scaling parameter w, it has a constant value w ≈ 3.0 ± 0.1 in a wide range of Nb 3 Sn superconductors. This is significant, because w is the only scaling parameter that requires very large data matrices of I c (B, T, ε) to determine its value. Unified scaling has been demonstrated in a number of different superconducting materials, including Nb 3 Sn, Nb 3 Al and more recently, the fundamentally distinct MgB 2 and Bi-2223 material systems. * This article is based in part on the presentation 'Unified strain-and-temperature scaling law: separable parameter set' given at the Mechanical and Electromagnetic Properties of Composite Superconductors Conference (Princeton, NJ, Aug. 2007). Trade names are used for identification purposes only and do not imply endorsement by NIST. Contribution of US Government, not subject to US copyright.

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