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Nb sub 3 Sn is a strain-sensitive superconductor which exhibits large changes in properties for strains of less than 1 percent. The critical current density at 12 T undergoes a reversible degradation of a factor of two for compressive strains of about 1 percent and undergoes an irreversible degradation for tensile strains on the Nb sub 3 Sn greater than 0.2 percent. Consequently, the successful application of Nb sub 3 Sn in large high-field magnets requires a complete understanding of the mechanical properties of the conductor. One conductor which is being used for many applications consists of filaments of Nb sub 3 Sn in a bronze matrix, and much progress has been made in understanding the mechanical behavior of this composite. The Nb sub 3 Sn filaments are placed in compression due to the differential thermal contraction between Nb sub 3 Sn and bronze which occurs when the composite is cooled from the Nb sub 3 Sn formation temperature (typically 700 exp 0 C) to the 4.2 exp 0 K operating temperature. The general behavior of the critical current when this conductor is subjected to a tensile stress is an increase to a maximum when the compressive strain on the Nb sub 3 Sn is relieved, followed by a decrease as the Nb sub 3 Sn filemants are placed in tension. The degree of precompression is controlled largely by the ratio of bronze to Nb sub 3 Sn in the conductor. (ERA citation 05:029299)