iii a of the resulting crimped joint the outer surface 48 of the crimp shows mechanical deformations 50 due to the crimping process the lining 52 of the crimp 46 has been converted to nb 3 sn within the crimp the sheaths 2 of filaments 4 of the wires 7 have also been converted to nb 3 sn they are pressed together into mechanical contact the mgb 2 cores 1 of the filaments 4 are electrically joined through nb 3 sn sheaths and the nb 3 sn lining of the crimp the nb 3 sn components are superconducting as discussed above and have much better superconducting characteristics than niobium for example in having a significantly greater field tolerance about 18 t at a temperature of 4k and a higher critical temperature about 18k nb 3 sn also has a relatively large coherence length the copper crimp 46 is unaffected by immersion in tin other than in gaining a tin coating while the resulting structure illustrated in fig1 may be immersed in molten superconducting filler material such as woods metal or pbbi which infuses between the filaments 4 and fills the crimp it is preferred not to include such jointing material the mechanical and electrical contact between nb 3 sn sheaths and nb 3 sn crimp lining layer provided by this embodiment of the invention may be sufficient to provide the required superconducting joint the resultant joint between multiple nb 3 sn connections without a filler material is expected to tolerate relatively high strength magnetic fields and remain superconducting at temperatures in excess of 10k such joints are expected to be useful in the manufacture of dry magnets cooled by thermal conduction by cryogenic refrigerators operating at about 10k the present exemplary embodiment accordingly provides methods for joining.