Further investigations of the solid-liquid reaction and high-field critical current density in liquid-infiltrated Nb-Sn superconductors

Conference · Fri Mar 01 04:00:00 EST 1985 · IEEE Trans. Magn.; (United States)

OSTI ID:6486180

Hong, M; Ekin, J W; Ellington, M B; Geballe, T H; Hellman, F; Holthuis, J T; Maher, D M

Superior superconducting properties, such as high J /SUB c/ 's and T /SUB c/ 's, have been obtained from reacted liquid-infiltrated Nb-Sn composite wires. These excellent properties are attributed to the chemistry and structure of the material, which is prepared by a unique solid (Nb) - liquid (Sn) reaction. From heat capacity measurements, sharp bulk superconducting transitions of the A15 phase occur at 17.2-18 K and the weight fraction of A15 in the composite wire is about 23%. Analytical electron microscopy techniques have shown that: the microstructure of these conductors consists of alternating largegrain and small-grain filaments; these two types of filaments correspond to BCC Nb(Sn) and cubic A15 Nb /SUB 75+or-x/ Sn /SUB 25+or-x/ phases, respectively; the A15 filaments (less than or equal to 0.5 ..mu..m) are chemically homogeneous in terms of measured X-ray intensity ratios to within + or - 7%, which implies that x about 1.5; and the A15 grains are essentially free of extended lattice disorder down to a resolution of about 0.34 nm. Recent work in which Nb is alloyed with Ta has shown that these superconducting properties can be improved upon; e.g. high overall J /SUB c/ 's of about 1.8X10/sup 4/ A/cm/sup 2/ at 20 T and 4.2 K have been measured. Also, the liquid-infiltrated Nb(Ta)-Sn composites have a damage strain tolerance nearly double that of commercial bronzeprocessed Nb-Sn conductors.

• Research Organization: ATandT Bell Laboratories, Murray Hill, NJ
• OSTI ID: 6486180
• Report Number(s): CONF-840937-
• Conference Information: Journal Name: IEEE Trans. Magn.; (United States) Journal Volume: MAG 21:2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CRITICAL CURRENT
CRITICAL TEMPERATURE
CRYSTAL-PHASE TRANSFORMATIONS
CURRENT DENSITY
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
MATERIALS
MEASURING METHODS
NIOBIUM ALLOYS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SUPERCONDUCTING COMPOSITES
SUPERCONDUCTIVITY
TANTALUM ALLOYS
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TRANSITION TEMPERATURE