Abstract: A method and article produced thereby are disclosed wherein the method produces a multi-filament superconductor having an insulation capable of withstanding extended heat treatment. According to the invention, a plurality of superconductor forming rods and a plurality of rods of normally conductive material are packed into a can made of a ductile material such as copper and having its interior lined with a valve metal such as tantalum. This assembly is extruded and drawn to a desired size as is known in the art. The ductile metal exterior layer is then removed to expose the valve metal. The exposed valve metal is thereafter oxidized to form an insulating oxide.

Abstract: A superconducting compound of the A-15 crystal structure type is obtained in a composite by a high temperature diffusion between a first metallic component and a second metallic component contained in a bronze alloy. Stability is achieved by including in the composite a quantity of high-conductivity normal material. Diffusion of the second metallic component into the normal material with a resultant degradation of conductivity of the normal material is prevented by placing an impervious barrier layer between the bronze alloy and the normal material. In a specific embodiment, the barrier layer takes the form of an annular shell comprising at least two sectors of dissimilar metals, one of which reacts with a component of the bronze alloy to form a layer of said superconducting compound, and the other of which is substantially non-reactive. Thus, a discontinuous superconducting ring is formed on the barrier layer which prevents flux trapping.