The extruded tube internal tin diffusion MF Nb3Sn superconducting material in Shanghai Institute of Metallurgy

The extruded MF Nb/Cu tube internal tin diffusion technique has been developed in Shangai Institute of Metallurgy (SIM) since the beginning of 1981. The diffusion behavior of a round Cu/Sn couple, the optimum homogenizing treatment of Cu/Sn diffusion in a composite of N81x26μm Nb fils./Cu/Sn/Sn-9Cu, and the effects of Sn concentration in Cu-Sn matrix on the thickness of the Nb/Sn diffusion layer and its critical current density are reported. The critical current density Jc (inside Ta barrier) at 4.2K and 10.7, 11.6, 12.5T, of a sample of dia. 0.50mm containing 2,310x5.3μm fils. reacted at 700 degrees C for 48h, were 8.5, 6.6, 4.8x104A/cm2 respectively. The critical carrying characteristics of Ti-containing MF Nb3Sn composites were measured in a pulsed field at 4.2K. The Jc (Nb+Nb3Sn) at 16 and 20T are 4x104 and 2.8x104A/cm2 respectively. MF Nb3Sn magnets were wound and reacted using 2,310 - 11,500 Nb fils./Cu/Sn-9Cu composite wires. The central field of a Nb3Sn/Nb-Ti hybrid magnet having clear bore of 18mm is 13T