Abstract: A composite superconductor that comprises a first alloy selected from the class consisting of Nb-Sn-X, V-Ga-X, and V-Si-X wherein X is selected from the class consisting of yttrium, tellurium, lanthanum, cerium, gadolinium, erbium, and mixtures thereof and is in an amount up to 300% of the solubility limit of X in the alloy; a second alloy selected from the class consisting of Cu-Ga, Cu-Ga-Al, Cu-Su, and Cu-Si; and a continuous layer of an intermetallic A-15 compound between the alloys, the layer being formed by a solid state reaction between the alloys.

Abstract: A composite superconductor which comprises:(1) A matrix sheath of a copper-base alloy containing from about 12 to ab 20 at. % of gallium and from about 0.2 to about 6 at. % of aluminum;(2) a core in said matrix sheath, said core being of a vanadium-base alloy containing from about 1.0 to about 9.5 at. % of gallium and from about 0.1 to about 2.5 at. % of titanium; and(3) a continuous interfacial layer of V.sub.3 Ga between said matrix sheath and said core.

Abstract: A multifilament composite superconductor which comprises (1) a matrix she selected from the group consisting of a copper-gallium (Cu--Ga) alloy with a gallium content from 0.4 to 22 at.%, a copper-tin (Cu--Sn) alloy with a tin content from 1 to 11 at. %, and a copper-silicon (Cu--Si) alloy with a silicon content from 0.5 to 14 at. %; (2) multiple filaments embedded in said encasing matrix sheath and selected from the class consisting of a vanadium -gallium (V--Ga) alloy with a gallium content from 0.4 at. % to 12.5 at. %, a niobium-tin (Nb--Sn) alloy with a tin content from 0.1 at. % to 12.0 at. %, and vanadium-silicon (V--Si) alloy with a silicon content from 0.5 to 10 at. %; and (3) a continuous interfacial layer between said matrix and each filament of an A-15 compound selected from the class consisting of V.sub.3 Ga, Nb.sub.3 Sn, and V.sub.3 Si.

Abstract: A composite superconductor which comprises (1) a first layer of an alloy ected from the group consisting of a vanadium-gallium (V--Ga) alloy with a gallium content from 12.5 at. % to 17.5 at. %, a niobium-tin alloy (Nb-Sn) with a tin content from 12 at. % to 17.5 at. %, and a vanadium-silicon (V--Si) alloy with a silicon content from 10.0 at. % to 20.0 at. %; (2) an intermediate layer of an A-15 compound selected from the group consisting of V.sub.3 Ga, Nb.sub.3 Sn, and V.sub.3 Si; (3) a third layer of an alloy selected from the group consisting of copper-gallium (Cu--Ga) alloy with a gallium content greater than 22 at. % but not greater than 30.0 at. %, a copper-tin (Cu-Sn) alloy with a tin content greater than 11 at. % but not greater than 21.0 at. %, and a copper-silicon (Cu--Si) alloy with a silicon content greater than 14 at. % but not greater than 21 at. %.