Further investigations of the solid-liquid reaction and high-field critical current density in liquid-infiltrated Nb-Sn superconductors
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-
- Journal Information:
- IEEE Trans. Magn.; (United States), Vol. MAG 21:2; Conference: Applied superconductivity conference, San Diego, CA, USA, 9 Sep 1984
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
36 MATERIALS SCIENCE
NIOBIUM ALLOYS
CURRENT DENSITY
FABRICATION
SUPERCONDUCTIVITY
TIN ALLOYS
CHEMICAL REACTIONS
CRITICAL CURRENT
CRITICAL TEMPERATURE
CRYSTAL-PHASE TRANSFORMATIONS
MEASURING METHODS
SUPERCONDUCTING COMPOSITES
TANTALUM ALLOYS
ALLOYS
COMPOSITE MATERIALS
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
MATERIALS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
420201* - Engineering- Cryogenic Equipment & Devices
360104 - Metals & Alloys- Physical Properties