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             Innovative Processing Methods for Superconducting Materials

Precursor materials for superconductors such as Nb₃Sn and Nb₃Al include low melting point components.  Therefore, conventional extrusion processes with large area reductions are not possible because adiabatic heating raises the temperature above the melting point.  In certain circumstances, hydrostatic extrusion could be used, as it can be operated at low enough speeds to allow the deformation heat to dissipate without raising the temperature excessively.  However, existing hydrostatic extrusion presses do not have sufficient extrusion volumes to process the large billets required for future magnet applications.  This project will combine hydrostatic extrusion and cold drawing to produce relatively large area reductions (~ 4:1) with acceptable adiabatic heating levels.  The process can be scaled up to handle billets that can produce single pieces with lengths of 10,000 meters of 1.0 mm diameter wire.    In Phase I the process will be simulated with an existing small hydrostatic extrusion press that will be fitted with a draw bench.  This will allow the process variables to be measured and the necessary control system to be demonstrated.  A preliminary design of a pre-production scale facility will also be completed.   

Commercial Applications And Other Benefits as described by awardee: Superconducting Nb₃Sn wire is currently restricted to a “niche” market because of its high cost, due primarily to manufacturing limitations.  End losses and breaks reduce process yields, resulting in a large volume of high-cost scrap with no value.  This fabrication technology could result in higher yields and lower cost products, and applications could be extended to other areas.  For example, composites that have material pairs with low eutectic formation temperatures could be processed.

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