A A Polyanskii et al 2009 Supercond. Sci. Technol. 22 095008 doi:10.1088/0953-2048/22/9/095008
A A Polyanskii1, P J Lee1, M C Jewell1, E Barzi2, D Turrioni2, A V Zlobin2 and D C Larbalestier1
Show affiliationsNb3Sn strands for high-current, high-field magnets must be cabled before reaction while the conductor is still composed of ductile components. Even though still in the ductile, deformable state, significant damage can occur in this step, which expresses itself by inhomogeneous A15 formation, Sn leakage or even worse effects during later reaction. In this study, we simulate cabling damage by rolling recent high performance powder-in-tube (PIT) and internal tin (IT) strands in controlled increments, applying standard Nb3Sn reaction heat treatments, and then examining the local changes using magneto-optical imaging (MOI), scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These combined characterizations allow any local damage to the filament architecture to be made clear. MOI directly reveals the local variation of superconductivity while CLSM is extremely sensitive in revealing Sn leakage beyond the diffusion barrier into the stabilizing Cu. These techniques reveal a markedly different response to deformation by the PIT and IT strands. The study demonstrates that these tools can provide a local, thorough, and detailed view of how strands degrade and thus complement more complex extracted strand studies.
84.71.Fk Superconducting cables
74.25.Ld Mechanical and acoustical properties, elasticity, and ultrasonic attenuation
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
Issue 9 (September 2009)
Received 1 June 2009, in final form 14 July 2009
Published 5 August 2009
A A Polyanskii et al 2009 Supercond. Sci. Technol. 22 095008
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