Development of in situ formed Nb/sub 3/Sn-Cu superconducting wire

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5017078

Sue, J

Flux pinning and the optimization of J/sub c/ properties have been studied for in situ prepared Nb/sub 3/Sn-Cu superconducting composite wire. The pinning force density is found to be a universal function of magnetic fields as F/sub p/ proportional to H/sup 1/2/(1-h)/sup 2/ over the full range of reduced field density, h, from h = 0.1 to h = 1.0. The experimental results for a wide range of micro-structures show that J/sub c/ is controlled by core pinning on surfaces of grain boundaries, and pinning by shear forces in flux line lattice at high fields is not important. The effective pinning area per unit volume calculated from theory is found to be equal to the area of the interfaces of Nb/sub 3/Sn-Nb/sub 3/Sn grain boundaries which are perpendicular to the filament axis. An attempt to increase J/sub c/ properties in these wires is made by eliminating C impurities, optimizing as-drawn Nb filament size, and alloying with the third element Ta. J/sub c/ is increased by a factor of 2 to 5 by reducing C content in the alloy from 380 ppmw to 15 ppmw. Optimum Nb filament thicknesses to produce maximum J/sub c/ and H/sub c2/* are found to be 600 A and 700 A for 550/sup 0/C diffusion annealing and 650/sup 0/C diffusion annealing, respectively. In addition, Ta additions in the alloy lead to an increase of J/sub c/ at magnetic fields above 12T. It is found that a small amount of Ta in composite wire can raise H/sub c2/* as well as J/sub c/.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5017078
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
656102* -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ANNEALING
CRYSTAL STRUCTURE
DATA
DENSITY
EXPERIMENTAL DATA
GRAIN BOUNDARIES
HEAT TREATMENTS
INFORMATION
MAGNETIC FLUX
MICROSTRUCTURE
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
NUMERICAL DATA
PHYSICAL PROPERTIES
SHEAR
SUPERCONDUCTING WIRES
TANTALUM ADDITIONS
TANTALUM ALLOYS
TIN ALLOYS
WIRES