Airco, Inc.

Wisconsin Alumni Research Foundation

American Superconductor Corporation

David C Larbalestier

Morris S Young

Gilbert N Riley, Jr

Qi Li

Elliott D Thompson

Eric E Hellstrom

Kenneth L DeMoranville

Paul D Jablonski

Jodi L Reeves

Jeffrey A Parrell

A method of making an oxide superconductor article includes subjecting an oxide superconductor precursor to a texturing operation to orient grains of the oxide superconductor precursor to obtain a highly textured precursor; and converting the textured oxide superconducting precursor into an oxide superconductor, while simultaneously applying a force to the precursor which at least matches the expansion force experienced by the precursor during phase conversion to the oxide superconductor. The density and the degree of texture of the oxide superconductor precursor are retained during phase conversion. The constraining force may be applied isostatically.

Simultaneous constraint and phase conversion processing of oxide superconductors

Superconductors formed by powder metallurgy have a matrix of niobium-titanium alloy with discrete pinning centers distributed therein which are formed of a compatible metal. The artificial pinning centers in the Nb-Ti matrix are reduced in size by processing steps to sizes on the order of the coherence length, typically in the range of 1 to 10 nm. To produce the superconductor, powders of body centered cubic Nb-Ti alloy and the second phase flux pinning material, such as Nb, are mixed in the desired percentages. The mixture is then isostatically pressed, sintered at a selected temperature and selected time to produce a cohesive structure having desired characteristics without undue chemical reaction, the sintered billet is reduced in size by deformation, such as by swaging, the swaged sample receives heat treatment and recrystallization and additional swaging, if necessary, and is then sheathed in a normal conducting sheath, and the sheathed material is drawn into a wire. The resulting superconducting wire has second phase flux pinning centers distributed therein which provide enhanced J.sub.ct due to the flux pinning effects.

Niobium-titanium superconductors produced by powder metallurgy having

A multifilamentary stabilized superconductor of the A-15 type is disclosed wherein the A-15 compound is formed on rods of niobium or vanadium by diffusion of tin or gallium, respectively, from a copper alloy matrix and wherein stabilization is provided by an external layer of copper. The stabilizing copper is protected from tin or gallium diffusion by a number of spirally wrapped layers of tantalum separated from one another by copper layers.

Wrapped tantalum diffusion barrier

Growing community of inventors

Madison, WI, United States of America

David C Larbalestier