Effect of ball milling on the local magnetic flux distribution and microstructure of in situ Fe/MgB2 conductors

Laliena, Carlos; Qureishy, Thomas; Martínez, Elena; Navarro, Rafael; Mikheenko, P.; Johansen, T. H.; Kòváč, Pavol

doi:10.1016/j.jallcom.2017.05.083

Cited by 8 publications

(6 citation statements)

References 26 publications

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“…Dendritic avalanches were found in only one of them, and the present paper focuses on detailed results for this particular sample. MOI results from the four undoped tapes are presented elsewhere [21]. Also an MgB 2 wire was synthesized and characterized by magnetic moment measurements.…”

Section: Methodsmentioning

confidence: 99%

“…The MgB 2 tape showing dendritic behaviour was manufactured by the powder-intube method using in situ reaction of ball-milled precursor powders, similarly to the process described in [21], but with oleic acid added to the powders before milling to improve its critical current density. Powders of Mg and B were mixed in stoichiometric ratio (1:2) with oleic acid in a Retsch MM 200 vibratory ball mill for 30 minutes.…”

Section: Methodsmentioning

confidence: 99%

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Dendritic flux avalanches in a superconducting MgB₂tape

Qureishy¹,

Laliena²,

Martínez³

et al. 2017

Supercond. Sci. Technol.

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Tapes of MgB 2 with high critical current have a significant technological potential, but can experience operational breakdown due to thermomagnetic instabilities. Such events are routinely registered by magnetisation measurements, but were never observed by direct imaging techniques. Here we report magneto-optical imaging visualisation of a tape with reduced thickness and enhanced critical current density. The spatial structure of the thermomagnetic avalanche events was resolved, and the reproducibility and nucleation thresholds were determined. Avalanches appearing at low fields are small intrusions at the tape edges, while larger fields create more extensive avalanches having dendritic structures similar to those observed in thinfilm superconductors. In contrast to dendritic avalanches in thin films, the avalanches in the tapes show reproducibility to a larger extent.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Dendritic flux avalanches in a superconducting MgB₂tape

Qureishy¹,

Laliena²,

Martínez³

et al. 2017

Supercond. Sci. Technol.

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“…However, the low J c of pristine MgB 2 is mainly caused by poor grain connectivity, porosity and weak flux pinning. Various attempts including chemical doping, additives, irradiation, ball milling and the optimization of fabrication processes have so far been used to try to improve the J c [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of J _c in C₆H₁₆N₂ added MgB₂ superconductor without carbon substitution for boron

Suo

Liu

et al. 2020

Supercond. Sci. Technol.

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The influence of C 6 H 16 N 2 addition on the microstructural and superconducting properties of MgB 2 was systematically investigated. Unlike previously reported carbon sources, the C 6 H 16 N 2 additive had no effect on the lattice parameters of MgB 2 . However, the obvious improvement of critical current density (J c ) was obtained for C 6 H 16 N 2 added MgB 2 without carbon substitution for boron. The average grain size was reduced with the addition of C 6 H 16 N 2 . Additionally, different numbers of spherical MgB 2 grains appeared inside the C 6 H 16 N 2 added MgB 2 . As the added amount of C 6 H 16 N 2 increased, the active cross-sectional area fraction (A F ) values first increased then decreased. The possible reasons for these results have been discussed. The additive C 6 H 16 N 2 resulted in a small depression in T c and slightly increased the ∆T c of MgB 2 at 0 T. The H c2 (T) and H irr (T) values of C 6 H 16 N 2 added MgB 2 samples are larger than those of pure MgB 2 at temperatures below 25 K. It was concluded that the reduced grain size and the improved grain connectivity were mainly correlated with the enhancement of the J c , F p , H c2 , and H irr performances in C 6 H 16 N 2 added MgB 2 superconductors.

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“…Dendritic avalanches were found in only one of them, and the present paper focuses on detailed results for this particular sample. MOI results from four other tapes are presented in [21]. An MgB 2 wire was synthesized as well, and characterized by magnetic moment measurements.…”

Section: Methodsmentioning

confidence: 99%

“…The MgB 2 tape was manufactured by the powder-in-tube method using in situ reaction of ball-milled precursor powders, similarly to the process described in [21], but with oleic acid added to the powders before milling to improve its critical current density. Powders of Mg and B were mixed in stoichiometric ratio (1:2) with oleic acid in a Retsch MM 200 vibratory ball mill for 30 minutes.…”

Section: Methodsmentioning

confidence: 99%

Dendritic flux avalanches in a superconducting MgB2 tape

Qureishy,

Laliena,

Martínez

et al. 2017

Preprint

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MgB 2 tapes with high critical current have a significant technological potential, but can experience operational breakdown due to thermomagnetic instability. Using magneto-optical imaging the spatial structure of the thermomagnetic avalanches has been resolved, and the reproducibility and thresholds for their appearance have been determined. By combining magneto-optical imaging with magnetic moment measurements, it is found that avalanches appear in a range between 1.7 mT and 2.5 T. Avalanches appearing at low fields are small intrusions at the tape's edge and non-detectable in measurements of magnetic moment. Larger avalanches have dendritic structures.

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Effect of ball milling on the local magnetic flux distribution and microstructure of in situ Fe/MgB2 conductors

Cited by 8 publications

References 26 publications

Dendritic flux avalanches in a superconducting MgB₂tape

Dendritic flux avalanches in a superconducting MgB₂tape

Enhancement of J _c in C₆H₁₆N₂ added MgB₂ superconductor without carbon substitution for boron

Dendritic flux avalanches in a superconducting MgB2 tape

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Effect of ball milling on the local magnetic flux distribution and microstructure of in situ Fe/MgB2 conductors

Cited by 8 publications

References 26 publications

Dendritic flux avalanches in a superconducting MgB2tape

Dendritic flux avalanches in a superconducting MgB2tape

Enhancement of J c in C6H16N2 added MgB2 superconductor without carbon substitution for boron

Dendritic flux avalanches in a superconducting MgB2 tape

Contact Info

Product

Resources

About

Dendritic flux avalanches in a superconducting MgB₂tape

Dendritic flux avalanches in a superconducting MgB₂tape

Enhancement of J _c in C₆H₁₆N₂ added MgB₂ superconductor without carbon substitution for boron