SBIR Phase II: Development of Artificial Pinning Center Niobium Titanium Superconductors with Optimal Overall Compositions

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9531315 Wong This Small Business Innovation Research Phase II project will investigate the possibility of varying the composition of Niobium Titanium (NbTi) superconductors by using a novel artificial pinning center approach. The technical objective of the Phase II is to develop a process for producing commercial scale billets via the Artificial Pinning Center (APC) process with compositions optimized for a particular applications. Two different compositions will be chosen, one for high field use, the other for low to intermediate field use. In addition the process to produce monofilamentary material will also be scale from R&D to commercial sized billets. All conventionally produced NbTi superconductors use a melted alloy of single composition, Nb47wt%Ti. Economic and technical limitations have prevented the use of other alloy compositions. The Supercon APC process uses pure Nb and Ti sheets as the starting material, thus overall NbTi composition can be varied simply by changing the thickness of the sheets. By varying composition, one should be able to optimized composition for particular applications. For example, conductor that is used at high fields (7T) must have the highest critical current densities at these fields. Thus the composition that is most optimal would be one that optimizes the upper critical field. For conductor that is used in low field applications, such as MRI, peak fields do not exceed 5T. In addition, these applications are very sensitive to conductor cost as measured by $/Kamp * M. In this case a higher Ti content alloy would be attractive. It has been shown that higher Ti content composites can achieve low field Jc's higher than the conventional melted alloy. The use of higher Ti content reduces the raw material costs, as the Ti replace Nb which is 2-4 times as expensive. This SBIR program will results in a highly economical process for the fabrication on NbTi superconductors with excellent Jc performance. Conventional NbTi alloy derived superconduc tors are the principle competing product for this Supercon APC material. Optimizing filament composition, elimination of the need for NbTi alloy and conventional precipitation heat treatments, and good ductility should provide the necessary cost advantage for APC material to compete successfully with conventional material. Among the applications that can benefit from these improvements are MRI, laboratory solenoids, magnetic ore separation, magneto-hydrodynamic propulsion, magnetic levitation, fusion and high energy physics magnets, and nuclear magnetic resonance.