Microstructure and J/sub c/-B performance of DRHQ processed Nb/sub 3/Al tape with Ag stabilizer

The DRHQ process was applied to the jelly-rolled Nb/sub 3/Al precursors having internal Ag stabilizers. The Ag internal stabilizer is effective to improve the superconducting stability of the DRHQ processed conductor with the Ag-stabilizer/non-Ag ratio of 0.32. The DRHQ process needs a reduction of a bending strain of the precursors, such as tape-formed specimen. The maximum T/sub c/ and B/sub c2/(4.2 K) of the DRHQ-processed tape with Ag stabilizer are 18.4 K and 29.7 T, respectively. Large transport core-J/sub c/(4.2 K) of 210 A/mm/sup 2/ was obtained at high magnetic field of 25 T, which is 20 times larger than that of the typical RHQT-processed wires. On the other hand, J/sub c/ in fields below 20 T apparently decreased with increasing the peak heating temperature during the second-RHQ. According to the TEM observation, the stacking faults were still formed in the DRHQ-processed Nb/sub 3/Al, but their density becomes very small compared with that of the RHQT-processed Nb/sub 3/Al. In addition, the stacking faults gradually vanished with increasing the peak heating temperature. The grain size of several hundred nanometers for the DRHQNb/sub 3/Al is still rather small. Thus, these results support that the stacking faults should be dominant as the effective pinning center for the both of RHQT- and DRHQ-processed Nb/sub 3/Al conductors.