THE EFFECT OF POWER METALLURGY CU(SN) APCS ON GRAIN-SIZE REDUCTION AND FLUX-PINNING IN NB3SN WIRE

Cu Artificial Pinning Centers (APCs) measuring 20 or 5 nm across were introduced to Nb3Sn and Nb3Sn(Ta) wire by means of powder metallurgy. The APCs increased the filament hardness by less than 10%. Stress anne als could be applied without affecting the Cu APC content or morpholog y. The Cu APCs led to a fine grained Nb3Sn, with an average grain size of 18 nm. The critical current over the filament area was 2250-2600 A /mm(2) at 12 T, virtually similar for the 20 and 5 nm APC wires, The C u APCs improved reaction kinetics.