Effects of metal powder addition on the structure and critical current of Ni-sheathed PIT MgB/sub 2/ tapes

Tachikawa, K.; Yamada, Yutaka; Enomoto, Masakazu; Aodai, Makoto; Kumakura, Hiroaki

doi:10.1109/tasc.2003.812221

Cited by 23 publications

(9 citation statements)

References 9 publications

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“…The wires were annealed at 873 K for 2 h in Ar atmosphere. The details of the specimen preparation are found in [5] and [9].…”

Section: Samplesmentioning

confidence: 99%

“…The transport critical current density of the core in the PIT MgB 2 conductors depends on such parameters as the raw powder quality, sheath material, fabrication procedure, heat-treatment condition, and so on. In order to improve the critical current I c , the addition of metal powders, such as indium (In), to the MgB 2 core has been tried by some of the present authors [5,6]. Among them, it has been shown that 10 vol% In addition and annealing enhances I c by a factor of 6 to 7.…”

Section: Introductionmentioning

confidence: 99%

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Stress–strain effects on powder-in-tube MgB₂tapes and wires

Katagiri

Takaya

Kasaba

et al. 2005

Supercond. Sci. Technol.

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The effects of stress-strain on the critical current, I c , of ex situ powder-in-tube (PIT)-processed Ni-sheathed MgB 2 tapes and round wires as well as in situ PIT-processed Cu-sheathed wires at 4.2 K in a magnetic field up to 5 T have been studied. The effect of In powder addition on the Ni-sheathed MgB 2 wire was not so clear compared with that in the tape, in which the irreversible strain, ε irr , for the I c degradation onset increases significantly by the addition. This is attributed to the difference in the microstructure of the core associated with cold workings. A peak and gradual degradation behaviour of I c with strain beyond ε irr was found in the wire, whereas no evident peak and a steep degradation behaviour was found in the tape. As a possible reason, the difference in the triaxial residual stress state at 4.2 K due to the difference in geometry of the cross-section is suspected. The transverse compression tests revealed that I c of the wire did not degrade up to 270 MPa. Again, the effect of In addition was minimal. The Young's modulus of MgB 2 , 31-41 GPa, at room temperature was estimated by a tensile test of Cu sheath wire using a high-accuracy extensometer and the law of mixtures. The tensile strain dependence of I c in the Cu sheath wire was similar to that in the Ni-sheathed wire, ε irr being 0.4%. However, the stress corresponding to ε irr , 50 MPa, was about 1/10 of that for the Ni-sheath wire and the irreversible transverse compressive stress, 150 MPa, was also lower. The effect of bending strain on the I c in Cu-sheathed wire was compared with that of the tensile strain.

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“…The wires were annealed at 873 K for 2 h in Ar atmosphere. The details of the specimen preparation are found in [5] and [9].…”

Section: Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stress–strain effects on powder-in-tube MgB₂tapes and wires

Katagiri

Takaya

Kasaba

et al. 2005

Supercond. Sci. Technol.

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“…The trials for enhancement of H c2 and J c in MgB 2 have been performed in single crystal, bulk, wire and thin film [66][67][68][69][70][71][72][73][74]. Two bands in MgB 2 (p and s bands) take part in not only the superconducting gap but also H c2 and its anisotropy (H // ab, H // c).…”

Section: Applicationmentioning

confidence: 99%

Superconductivity in MgB2

Muranaka¹,

Akimitsu

2011

Zeitschrift Für Kristallographie

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“…The anisotropy in the B irr of MgB 2 with respect to the direction of applied field is also illustrated 4) . 14) .…”

Section: Figmentioning

confidence: 99%

Metallic Superconductors [7] - MgB2 Wires -

恭治¹

2011

TEION KOGAKU

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Synopsis: Since the discovery in 2001, MgB 2 has gained much interests as a new hope of superconductors for its applicability at temperatures of liquid H 2 (~20 K) or liquid Ne (~27 K). Then large efforts have been dedicated to the processing of MgB 2 wires. Ex situ and in situ techniques are two major techniques for the fabrication of MgB 2 wires. The ex situ process uses previously reacted MgB 2 powders filled into appropriate sheath tubes which are then fabricated into a wire. In the in situ process a mixture of Mg and B powders is encased in a sheath tube, and after the wire fabrication, the MgB 2 core is synthesized in situ by the heat treatment. C or SiC nano-powders are effective dopants to enhance the high-field performance of MgB 2 wires. Wires a few kilometers long have been produced via both processes. The diffusion process starting from a composite of Mg rod or pipe and B powder is another promising process in MgB 2 wire fabrication. The connectivity of MgB 2 grains is still poor due to the insufficient packing factor of powders, voids caused by the volume contraction during MgB 2 formation, and the envelope of MgO and other insulating phase around MgB 2 grains. This poor connectivity reduces the critical current density of MgB 2 wires. Improved powder quality, fabrication techniques, and dopants may appreciably improve the performance of MgB 2 wires. Presently, the main target of MgB 2 wire application is direct-current use at 20 K, such as for MRI magnets. In this article, material aspects, fabrication process, superconducting performance and future possibilities of MgB 2 wires are briefly surveyed.

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Effects of metal powder addition on the structure and critical current of Ni-sheathed PIT MgB/sub 2/ tapes

Cited by 23 publications

References 9 publications

Stress–strain effects on powder-in-tube MgB₂tapes and wires

Stress–strain effects on powder-in-tube MgB₂tapes and wires

Superconductivity in MgB2

Metallic Superconductors [7] - MgB2 Wires -

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Effects of metal powder addition on the structure and critical current of Ni-sheathed PIT MgB/sub 2/ tapes

Cited by 23 publications

References 9 publications

Stress–strain effects on powder-in-tube MgB2tapes and wires

Stress–strain effects on powder-in-tube MgB2tapes and wires

Superconductivity in MgB2

Metallic Superconductors [7] - MgB2 Wires -

Contact Info

Product

Resources

About

Stress–strain effects on powder-in-tube MgB₂tapes and wires

Stress–strain effects on powder-in-tube MgB₂tapes and wires