Method of production multifilamentary intermetallic superconductors

In the method of manufacturing a composite multi-filamentary superconductor of the type A.sub.3 B where A is selected from the group consisting of Nb and V, and B is selected from the group consisting of Sn and Ga by

• (a) forming a composite billet having a plurality of filaments of A embedded in a matrix of Cu and having a source of B external to the Cu matrix,
• (b) extruding said composite billet to reduce its cross sectional area and increase its length,
• (c) wire drawing the extruded product to the final conductor cross sectional area, and
• (d) heat treating the so reduced conductor to cause the B material to diffuse into and through the Cu and react with the filaments of A to form A.sub.3 B,
• the improvement which comprises
• providing the B material external to the Cu matrix in the preextrusion billet in the form of surrounding concentric uniform thickness annual layers of B surrounded by concentric annular layers of Cu, the thickness of B being approximately, but not exceeding, 0.50 mm per layer, and
• providing a plurality of such layers of B material and Cu, the number of such layers being determined by the total amount of B material required to react with the available A material to form A.sub.3 B.