TY - JOUR
T1 - Strain effects in high temperature superconductors investigated with magneto-optical imaging
AU - Van der Laan, D. C.
AU - Van Eck, H. J.N.
AU - Ten Haken, B.
AU - Ten Kate, H. H.J.
AU - Schwartz, J.
N1 - Funding Information:
Manuscript received August 6, 2002. This work was supported in part by the U.S. Air Force Office of Scientific Research and by FOM (Fundamental Research on Matter), which is subsidized by NWO. D. C. van der Laan is with the University of Twente, Enschede, The Netherlands, and National High Magnetic Field Laboratory, Tallahassee, FL 32310 USA (e-mail: d.c.vanderlaan@tn.utwente.nl). H. J. N. van Eck, B. ten Haken and H. H. J. ten Kate are with the University of Twente, Enschede, The Netherlands. J. Schwartz is with the National High Magnetic Field Laboratory, Tallahassee, FL 32310 USA, and also with Department of Mechanical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 USA. Digital Object Identifier 10.1109/TASC.2003.812392
PY - 2003/6
Y1 - 2003/6
N2 - In order to determine the influence of intermediate deformation steps on the mechanical behavior of Bi-based tapes, the effect of longitudinal applied strain is investigated by means of magneto-optical imaging. The strain is applied in a helium flow-cryostat. Cracks appear soon after the critical current in Bi-based tapes is degraded. All filaments form multiple cracks that grow into tape-wide cracks, running from one filament to the next. The crack location is not caused by stress concentrations in the matrix, but by the mechanically weak colony boundaries. Because of the absence of intermediate rolling steps in the production of Bi2Sr2CaCu2Ox tapes, a different crack structure is observed compared to Bi2Sr2Ca2Cu2Ox tapes. The relation between the critical current and the formation of cracks is studied. The degradation in critical current before the critical strain is reached may be caused by microcracks that remain undetected by magneto-optical imaging. The influence of strain on the microstructure of YBa2Cu3Ox coated conductors is also investigated with magneto-optical imaging. The formation of cracks is believed to be determined by the nickel substrate and related to the Ni-grain size.
AB - In order to determine the influence of intermediate deformation steps on the mechanical behavior of Bi-based tapes, the effect of longitudinal applied strain is investigated by means of magneto-optical imaging. The strain is applied in a helium flow-cryostat. Cracks appear soon after the critical current in Bi-based tapes is degraded. All filaments form multiple cracks that grow into tape-wide cracks, running from one filament to the next. The crack location is not caused by stress concentrations in the matrix, but by the mechanically weak colony boundaries. Because of the absence of intermediate rolling steps in the production of Bi2Sr2CaCu2Ox tapes, a different crack structure is observed compared to Bi2Sr2Ca2Cu2Ox tapes. The relation between the critical current and the formation of cracks is studied. The degradation in critical current before the critical strain is reached may be caused by microcracks that remain undetected by magneto-optical imaging. The influence of strain on the microstructure of YBa2Cu3Ox coated conductors is also investigated with magneto-optical imaging. The formation of cracks is believed to be determined by the nickel substrate and related to the Ni-grain size.
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U2 - 10.1109/TASC.2003.812392
DO - 10.1109/TASC.2003.812392
M3 - Conference article
AN - SCOPUS:0041473432
VL - 13
SP - 3534
EP - 3539
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
SN - 1051-8223
IS - 2 III
T2 - 2002 Applied Superconductivity Conference
Y2 - 4 August 2002 through 9 August 2002
ER -