The influence of Nb3Sn strand geometry on filament breakage under bend strain as revealed by metallography
| Autor: | David C. Larbalestier, M. C. Jewell, Peter J. Lee |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Materials science
Strain (chemistry) Composite number Metals and Alloys macromolecular substances Condensed Matter Physics Conductor Protein filament Cracking Breakage Ultimate tensile strength Materials Chemistry Ceramics and Composites Metallography Electrical and Electronic Engineering Composite material |
| Zdroj: | Superconductor Science and Technology. 16:1005-1011 |
| ISSN: | 1361-6668 0953-2048 |
| DOI: | 10.1088/0953-2048/16/9/308 |
| Popis: | The non-Cu critical current density of Nb3Sn strands has been pushed towards 3000 A mm−2 (12 T, 4.2 K) by increasing the Sn content and reducing the inter-filamentary Cu. We compare the susceptibility to A15 filament breakage (under 0.5% bend strain) of the new high-Jc internal Sn conductor geometries with both high-Jc powder-in-tube (PIT) and low hysteresis loss distributed filament ITER designs. In all but the PIT designs, there was significant filament breakage on the tensile side of the strand cross-section with little if any evidence for cracking on the compressive side. Where there is significant inter-filamentary Cu remaining after reaction the highest frequency of A15 filament breakage is observed at the edges of the filament packs. This suggests that the breakage is most likely to occur where filaments receive less mechanical support from the filament-Cu matrix. In very high Jc strands, where individual Nb filaments coalesce into large A15 tubes during reaction, breakage can occur across the entire sub-element. In the PIT design composite, filament breakage did not occur at 0.5% bend strain. At 0.6% bend strain the PIT filaments cracked in both the tensile and compressive regions. |
| Databáze: | OpenAIRE |
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