Superconductivity in filamentary CuNb composites produced by powder metallurgy

Composite wires with discontinuous Nb filaments embedded in a Cu matrix are produced by hot extrusion of a powder mixture and subsequent wire drawing. The specimens exhibit superconductivity with critical current densities in zero field up to 4×104 A/cm2 at 4.2 K (after a reduction of the cross‐section area of 5×104 by wire drawing). The origin of resistanceless currents in these materials with only 10 wt% Nb is due to superconducting bridges between the filaments which are formed by the proximity effect. The critical currents are drastically enhanced by a final heat treatment, by which additional Nb precipitates are produced in the Cu marix.

[1]  O. Izumi,et al.  Superconductivity in dilute Cu-Nb-Sn alloys containing Nb3Sn precipitates , 1978 .

[2]  H. Freyhardt,et al.  Superconducting composites produced by rapid quenching , 1978 .

[3]  B. B. Schwartz,et al.  High‐field critical current in in situ multifilamentary Cu‐Sn‐Nb alloys , 1977 .

[4]  J. Harbison,et al.  Superconducting and mechanical properties of in situ formed multifilamentary Cu‐Nb3Sn composites , 1977 .

[5]  H. Luo.  Composite superconductors of Cu(Sn)/Nb(Al) , 1977 .

[6]  R. Roberge,et al.  Origin of superconductivity in copper niobium alloys , 1977 .

[7]  A. Gupta,et al.  Superconductivity in a dilute copper—niobium alloy , 1975 .

[8]  M. Beasley,et al.  Remnant resistance in TSUEI'S composite superconductors , 1975 .

[9]  G. Frommeyer,et al.  Anomalous properties of in-situ-produced silver-copper composite wires I. Electrical conductivity , 1975 .

[10]  C. Tsuei,et al.  Critical current density of a superconducting copper‐base alloy containing Nb3Sn filaments , 1974 .

[11]  C. Tsuei.  Ductile Superconducting Copper-Base Alloys , 1973, Science.

[12]  W. Desorbo.  Effect of Dissolved Gases on Some Superconducting Properties of Niobium , 1963 .

[13]  L. Schultz,et al.  Superconducting properties of powder metallurgically produced Cu‐Nb3Sn composite wires , 1978 .

[14]  L. Toth,et al.  Electrical resistivities of normal-superconducting two-phase mixtures , 1975 .

[15]  P. D. Gennes,et al.  Superconductivity of metals and alloys , 1966 .