FOERFARANDE FOER FRAMSTAELLNING AV AVLAONGT FOEREMAOL

PCT No. PCT/GB91/01097 Sec. 371 Date Jan. 5, 1993 Sec. 102(e) Date Jan. 5, 1993 PCT Filed Jul. 5, 1991 PCT Pub. No. WO92/01316 PCT Pub. Date Jan. 23, 1992.A component 10 for making A15 Nb3Sn superconducting wire is of plane-filling cross-section after removing temporary additions 6, 7. It consists of a central pillar 1 of aluminium (later replaced by tin) surrounded by a two-deep array of polygonal copper columns 2/2a containing niobium rods. Many (e.g. 61) components 10 are voidlessly stacked together and extruded. The niobium rods adopt and retain a uniform distribution with minimum intervening material. This "sixty-one" member retains its shape during the extrusion and is itself of plane-filling cross-section. Several of them are voidlessly stacked together and on heat-treatment of the whole, the tin diffuses over a relatively short path and hence consistently into the rods, whereby there is formed a kilofilament Nb3Sn wire.