A NIOBIUM-TIN MULTIFILAMENTARY COMPOSITE SUPERCONDUCTOR WITH ARTIFICIAL COPPER (BRONZE) INCLUSIONS

THE DEVELOPMENT OF APPLIED SUPERCONDUCTIVITY CONTINUOUSLY REQUIRES ADVANCED SUPERCONDUCTING WIRES THAT CAN CARRY HIGHER SUPERCURRENTS AT HIGHER MAGNETIC FIELDS. NIOBIUM-TIN (NB3SN) IS ONE OF THE MOST IMPORTANT HIGH FIELD SUPERCONDUCTORS. DEVELOPING ARTIFICIAL FLUX-PINNING CENTERS IN THE SUPERCONDUCTING MATRICES IS ONE OF THE EFFECTIVE APPROACHES (BESIDES ALLOYING NB3SN WITH OTHER ELEMENTS) TO ENHANCE THE CRITICAL CURRENT DENSITY OF NB3SN IN INTERMEDIATE TO HIGH MAGNETIC FIELDS (10-20 T). THIS PROJECT INVESTIGATES THE FEASIBILITY OF DEVELOPING AN NB3SN MULTIFILAMENTARY SUPERCONDUCTING WIRE WITH ARTIFICIAL COPPER (BRONZE) INCLUSIONS, USING A JELLYROLL AND INTERNAL TIN APPROACH TO ENHANCE THE CRITICAL CURRENT DENSITY IN MAGNETIC FIELDS >10 T. IT HAS BEEN DEMONSTRATED THAT ARTIFICIAL TANTALUM INCLUSIONS CAN CONTRIBUTE TO THE OVERALL FLUX PINNING IN THE NB3SN SUPERCONDUCTORS. CU HAS AN EXCELLENT DUCTILITY AND DISPLAYS GOOD COMPATIBILITY WITH NIOBIUM (NB) DURING COLD WORKING. IT IS ANTICIPATED THAT THE USE OF COPPER AS ARTIFICIAL FLUX-PINNING INCLUSIONS WILL IMPROVE THE FABRICABILITY OF THE COMPOSITE WIRE AND REDUCE THE COST. IN PHASE I, A MULTIFILAMENTARY NB/CU COMPOSITE WIRE WITH INTERNAL TIN SOURCES (WHERE EACH SUBELEMENT HAS AN NB/CU JELLYROLL CONFIGURATION) IS BEING FABRICATED WITH CONVENTIONAL WIRE-MANUFACTURING TECHNIQUES. TIN (SN) DIFFUSES THROUGH THE COPPER MATRIX AND REACTS WITH NIOBIUM TO FORM NB3SN DURING THE FINAL REACTION HEAT TREATMENT. THE CRITICAL CURRENT DENSITIES OF SUCH A WIRE WILL BE MEASURED AS A FUNCTION OF THE APPLIED MAGNETIC FIELDS AND COMPARED WITH THE PERFORMANCES OF OTHER NB3SN WIRES. THE ALLOYING-ELEMENT ADDITION, OPTIMIZATION, AND SCALE-UP WORK WILL BE CONDUCTED IN THE PHASE II PROGRAM.