High transport critical current density obtained for powder-in-tube-processed MgB2 tapes and wires using stainless steel and Cu-Ni tubes

MgB2 tapes and wires were fabricated by the powder-in-tube method. Stainless steel and Cu-Ni tubes were used as sheath materials, and no heat treatment was applied. The tapes made of stainless steel showed transport critical current density J(c) of about 10 000 A/cm(2) at 4.2 K and 5 T. A high J(c) of about 300 000 A/cm(2) was obtained by extrapolating the J(c)-B curves to zero field. Multifilamentary (seven-core) MgB2 wire was successfully fabricated using Cu-Ni tubes. For both tapes and wires, the grain connectivity of MgB2 was as good as a high-pressure sintered bulk sample. However, the J(c) of the Cu-Ni sheathed wire was lower than the stainless steel sheathed tape due to the lower packing density of MgB2. (C) 2001 American Institute of Physics.