a) preparing a composite having a bronze matrix containing Cu and Sn in which at least one elongated structure containing Nb, a Nb alloy, or NbTa is embedded;

b) extruding the composite at a temperature between 300° C. and 750° C.;

c) elongating the composite in parallel to the elongated structure;

d) annealing the composite;

e) stacking a plurality of annealed elongated composites, following steps a) through d), into a composite bundle;

f) repeating steps a) through e) at least one time; and

g) elongating the composite bundle following step f) in a final elongating procedure, the final elongating procedure comprising at least one intermediate annealing process in which the composite bundle is elongated to a final length, a superconductive phase being obtained by a heat treatment including a solid state diffusion reaction, wherein at least some of steps c) and d) comprise intermediate annealing of the composite bundle at a temperature above a normal Cu—Sn re-crystallization temperature and between 520° C. and 750° C. followed by fast cooling within less than 30 s to 100° C. or below (Rapid Intermediate Quenching or RIQ) and cold working the composite.