A Method to Increase Current Density in a Mono Element Internal Tin Processed Superconductor Utilizing Zirconium Oxide to Refine Grain Size

65026 Magnets for the next generation of high energy physics accelerators require improved superconductor performance to enable magnetic fields up to 15T. The superconductors must also be cost effective so that the magnets, and hence the accelerators, will be economically viable. This project will develop a process for improving the current carrying capacity of the superconducting filaments within the Nb3Sn superconducting material by introducing a strong oxide-former and oxygen to form sites that will pin the grain boundaries and hence the fluxoids. The Nb filaments will be replaced by Nb1at.%Zr and the properties of this material, with and without additional oxygen, will be compared with each other and with the conventional Nb-based material. Phase I demonstrated that casting the alloy with a significant amount of oxygen led to a material that was difficult to fabricate. Fabricability was improved when commercially available Nb1at.%Zr was used to remove most of the oxygen from the Zr containing alloy. It was determined that the ideal stage for the introduction of oxygen is late in the process to maintain maximum fabricability. Phase II will explore various methods of introducing oxygen to maintain maximum fabricability. Oxygen will be introduced into the copper and then used to internally oxidize the Nb1at.%Zr before the Sn reacts to form Nb3Sn. The properties of material containing commercial Nb1at.%Zr with various levels of oxygen will be compared with those of material made from pure Nb. Commercial Applications and Other Benefits as described by the awardee: Lower cost superconductors should reduce the cost of MRI machines and expand the range of applications for MRI, a billion dollar industry. Their use at higher temperatures would allow the use of helium-free devices, making MRI technology more available to the Third World and remote sites. Other applications should exist in the utility sector.