Nb-Al powder metallurgy processed multifilamentary wire

Powder metallurgy processed Nb-Al wire with overall critical current densities, J
c
, at 4.2K up to 10
⁴
A/cm
²
at 19T has been investigated in more detail, Kramer plots and directly measured H
c2
values of samples with different heat treatments show an increase in H
c2
at 4.2K up to 24.5T. Test coils, using long lengths of wire, and tested in fields up to 15T, show J
c
values equal to those of short samples. Multiple strand hydrostatic small scale extrusions were made. A number of third element additions including B, Mg, Co, Cr and Ni in fine powder form were incorporated in the P/M processing but these did not improve J
c
. ac losses were measured and used to determine J
c
at 10w fields. The high field ac losses are lower than that for any In Situ or powder processed Nb
3
Sn wires.