Tempering superconducting intermetallic cpds. - of vandium or niobium, increases transition temp. and magnetic field strength

摘要

Increasing the transition temp. Tc, and/or critical magnetic field strength, Hc2, of familiar intermetallic cpds. (I) of V or Nb of the type A3B with beta W/A15 structure is achieved by forming ductile alloys based on V or Nb with max. 12 wt. % Al, Ga, Si, Ge and/or Sn. The improvement comprises heating these to 1500-2000 degrees C and then cooling rapidly below 500 degrees C. then heating to 600-1000 degrees C until the high Tc and/or high Hc2, is reached. Ductile and intrinsically stable superconductors are obtd. which permits operation with liquid H2. In an example, treatment of the V-V3Si system (5 wt. % Si) increased Tc from 17 degrees K to 28 degrees K. The Hc2 mix. value was 900 kG.