Development of high field superconductors for high energy particle physics: Progress report, June 1, 1985-August 31, 1985

During this quarter, the behavior of Nb and Cu when subjected to high temperatures was examined by measuring the microhardness vs. annealing time at 800/degree/C. this should help to more thoroughly understand the changes which would occur in the different conductor components when subjected to the heating inherent in the wire manufacturing process. Further experiments were also performed using the 1006 filament tubular conductor manufactured previously. A portion of this conductor was drawn, hexed (0.365''ff), straightened, cut to length, and restacked to form a 19114 filament trial billet (2'' OD) with a Ta diffusion barrier. After Hot Isostatic Pressing and inserting of Sn/endash/3 wt/percent/ Ti cores into the subelements, drawing of the restacked billet began at the end of this quarter. Results from the processing of this billet should help to determine whether or not HIP'ing is beneficial to the wire properties, and whether hexagonal subelements improve filament array uniformity. For the full scale billets, the preparation of pure copper hexagonal filler wire has begun. Also, two more monofilament billets have been extruded to 0.840'' OD. While the first monofilaments produced had a Cu:Nb ratio of 1.2:1, these two batches of monofilament will have a Cu:Nb ratio of 1.6:1. Thus the filament spacing in the restacked billets will be different, which will help to determine the optimal spacing for prevention of bridging while maintaining current density