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Rare-earth cuprate-based (REBCO) superconductors are a family of high-field, high-temperature superconductors fabricated in a tape geometry. The tape structure is composed of a nickel-based Hastelloy substrate base, with oxide buffer layers (to allow for epitaxial growth of the superconductor) and a superconducting film of thickness < 2 μm. The composite is finished with a silver cap layer and a Cu stabilizing layer. One limiting factor for REBCO tapes in a superconducting magnets is the possibility of transverse delamination within the tape; however, the microstructural features that control this delamination behavior are not fully understood. For this study we have developed new sample preparation methods (and subsequent imaging by SEM and laser confocal microscopy) to quantify the damage modes present in delaminated samples. Specifically, we investigate the morphology of the delaminated surface and the retained layers on the tape to ascertain the nature of the crack initiation and propagation. Ultimately, a more thorough understanding of the delamination behavior of this material may lead to improvements in the tape processing to minimize this effect in the future.
Acknowledgments: This work was financially supported by the U.S. Department of Energy, Office and High Energy Physics, award DE-FG02-13ER42036, and benefited from the support of the Materials Science & Engineering Center at UW-Eau Claire. The authors thank SuperPower, Inc. for providing the samples under investigation.