Fabrication of MgB2 superconducting wires with a hybrid method combining internal-Mg-diffusion and powder-in-tube processes

Shujun Ye, Akiyoshi Matsumoto, Kazumasa Togano, Yunchao Zhang, Takahito Ohmura, Hiroaki Kumakura

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

We have previously reported that the addition of Mg powder to the B powder layer (B layer) of internal-Mg-diffusion (IMD)-processed MgB2 wires can decrease the amount of unreacted B particles, and hence increase the critical current density (Jc). As the amount of Mg powder is increased, the diameter of the central Mg rod must be reduced in order to maintain an overall Mg:B molar ratio of 1:2, corresponding to stoichiometric MgB2. If this ratio is achieved by the Mg powder alone, then the required diameter of the Mg rod is zero, which means that the IMD process becomes the powder-in-tube (PIT) process. A hybrid process intermediate between the IMD and PIT processes is proposed as a new approach for fabricating MgB 2 wires. In the present study, the critical current and microstructure of MgB2 wires fabricated using this method are investigated. It is found that the method yields a higher engineering critical current density (Je, = Jc × MgB2 area fraction, where the MgB2 area fraction corresponds to the ratio of the MgB2 cross-sectional area to the total cross-sectional area of the wire) than that for either the IMD or the PIT method. Compared with the IMD method, the MgB2 layer thickness (the thickness of the MgB 2 layer in the transverse cross section) is increased and the diameter of the central hole is decreased, thus increasing the MgB2 area fraction The proposed method also achieves a much higher MgB2 layer density, and thus a much higher Jc, than is possible using the PIT method. The combination of these factors leads to the enhanced Je value of MgB2 wires.

Original languageEnglish
Article number055017
JournalSuperconductor Science and Technology
Volume27
Issue number5
DOIs
Publication statusPublished - 2014 May
Externally publishedYes

Keywords

  • critical current
  • hybrid IMD/PIT method
  • internal Mg diffusion (IMD)
  • Mg addition

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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