Material issues in the 100 T non-destructive magnet

Abstract

The effort in materials program related to the first 100 T non destructive (100 T ND) magnet has been concentrated on four areas: (a) development of the fabrication routes for various conductive wires in collaboration with other institutes and industrial partners, (b) investigation of the properties of a variety of candidate high strength high conductivity materials, (c) selection of the reinforcement materials for the coils and development of fabrication routes for these materials, (d) characterization of the commercially available insulation materials. This paper deals with the conductor issues. The properties and the microstructure of Cu-Ag, UNS-C157XX (Cu-Al/sub 2/O/sub 3/), Cu+Stainless Steels (SS) and Cu-Nb composites have been investigated for their potential use as conductors in pulsed high field magnets. These conductors demonstrate a combination of good conductivity, high strength, adequate workability, and the availability of final section sizes needed for the magnet design. Examination of the initial portion of the stress strain curve of cold worked conductors reveals that the internal stresses developed during the fabrication influence the mechanical response of the materials. Thus, the properties of the drawn materials have been measured as a function of cyclic loading and thermal annealing cycles, and the cyclic properties are related to the internal stresses.