Conventionally Processed NbTi Superconductors with Artificial Ferromagnetic Pinning Centers for High Magnetic Field (>8 T) Application

172 Conventionally Processed NbTi Superconductors with Artificial Ferromagnetic Pinning Centers for High Magnetic Field (>8 T) Application--Supercon, Inc., 830 Boston Turnpike, Shrewsbury, MA 01545-3301; (508) 842-0174 Mr. Charles Renaud, Principal Investigator Ms. Elaine Drew, Business Official DOE Grant No. DE-FG02-97ER82487 Amount: $74,997 The use of niobium-titanium (NbTi) superconductor has been restricted primarily to fields of less than 9 T because of the material¿s upper critical field of 11-12 T at 4.2K. Superconducting magnets in future accelerators will be required to operate in the 8-12 T range. In order to reach these high fields the magnets will operate in superfluid helium at 1.8 K. The objective of this project is to develop a NbTi conductor for 10 T operation at 1.8 K. This conductor would be conventionally processed, i.e., would receive multiple a-titanium precipitation heat treatments, but would also contain artificial ferromagnetic pinning centers to further enhance the critical current density. In addition mechanical mixing of the diffusion barriers with the matrix at final size should result in the formation of a ternary alloy and an increase in the upper critical field. During Phase I the hybrid wires will be given from one to four heat treatments and evaluated for drawability. The processable wires will then be drawn until the nickel pins reach a diameter of 5 nm (the size at which the pinning force is maximum) and tested for critical current density and upper critical field against appropriate control wires. Samples of hybrid wires will also be examined via transmission electron microscopy to determine microstructure and barrier integrity. Phase II will develop a fully stabilized scaled-up superconductor, optimize conductor performance, and establish a potential customer product evaluation program. Commercial Applications and Other Benefits as described by the awardee: This project should result in a NbTi-based composite for use in high field (>8 T), low temperature (1.8 K) applications. It should be an ideal candidate to be used in the superconducting magnets for accelerator, fusion, and nuclear magnetic resonance projects.