Abstract
Applying the powder in tube (PIT) method, single-filament MgB2/Fe wire
and tape has been manufactured applying both the ex situ and the in situ
approach. The influence of the roll diameter in three-step flat rolling on the
powder density and critical temperature has been examined using rolls of
70, 150 and 210 mm in each step. The investigation has shown that the
in situ powder is more readily compacted than the ex situ powder, with an
average increase of relative density after mechanical processing of 37% for
in situ powder and 19% for ex situ powder. Statistical analysis showed that
the choice of roll diameter had the largest influence in the first of the three
reductions used in the flat rolling. In this first reduction, for ex situ tapes,
rolls of 70 or 150 mm proved best, whereas the 70 mm roll appeared
best for in situ tapes. Overall, the evidence suggested that the combination of
the 70 mm roll in the first and second reductions followed by the 150 mm
or 210 mm roll in the last reduction was the optimum strategy for both
powder types. AC susceptibility testing showed that for the in situ tapes there
was no correlation between the powder density and the critical temperature.
For ex situ tapes the critical temperature correlated to some degree with the
powder density; also the critical temperature proved to be more sensitive to
the powder density for ex situ samples.
Original language | English |
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Journal | Superconductor Science and Technology |
Volume | 20 |
Pages (from-to) | 886-890 |
ISSN | 0953-2048 |
Publication status | Published - 2007 |