Some Improved Methods of Introducing Additional Elements into Internal-tin Nb3Sn

72046S03-I In order to achieve the required properties for the internal-tin Nb3Sn superconductor for the next generation of high field accelerator magnets, it is necessary to add a third element to the material. One method has been to add Ti to the Sn core, an expensive process that has led to severe ductility problems. This project will identify improved methods of introducing additional elements, particularly Ti and Ta, into internal-tin Nb3Sn, providing a more uniform distribution of the third element at a lower cost compared to present methods. In Phase I, subelements from three 50.8mm (2¿) diameter billet designs will be made into 19 subelement multiple barrier restacks. All will contain Nb 47.5 wt.% Ti foils as a method of introducing the Ti, and the alloy foil thickness will be varied. Two billets will contain Nb rods, and one will contain Nb 7.5 wt.% Ta rods. The products will be heat treated under a variety of conditions and examined metallographically. Finally, tests of Jc will be made over a range of fields, magnetization, and RRR. In Phase II, the most promising will be selected, optimized, and scaled up to full sized billets. COMMERCIAL APPLICATIONS and OTHER BENEFITS as described by the awardee: In addition to being used in HEP accelerator applications, the product should have application to open area MRI where the patient is more accessible to the surgeon (MRI is the largest commercial application of low temperature superconductors), small magnets for high field laboratory applications and NMR, and levitated transportation projects.