DEVELOPMENT OF MANUFACTURING METHODS FOR HARD SUPERCONDUCTORS (WIRES AND RIBBONS)
MATERIALS RESEARCH CORP ORANGEBURG NY
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A fabrication procedure was developed and utilized to produce copper clad Nb3Sn wires in lengths greater than 1000 ft and niobium clad Nb3Sn wires in lengths greater than 200 ft. Shorter lengths of ribbon of both materials were also produced. The optimized fabrication procedure for these materials consists of a combination of rolling and drawing operations, the exact schedule being dependent on the metal sheath employed and the ultimate size desired. For copper clad material the composite is rolled to approximately 0.100 in. diameter and then drawn to final size. The niobium clad composites are rolled to about 0. 125 in. diameter, inserted into a copper tube, rolled further to about 0.100 in. diameter, and then drawn to final size. Bare niobium clad specimens were also rolled to a final size of 0.030 in. diameter. Pertinent process variables that were established are as follows a 16 hr at 1000 C is sufficient for preforming the Nb3Sn powder, b a minimum of 16 hr at 950 C is required for the final anneal, c air or water quenches from the final anneal are satisfactory but furnace cooling impairs the superconducting properties, and d swaging operations should not be used in the reduction process.
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