Filamentary niobium--tin superconductors fabricated by a powder metallurgy approach

Technical Report · Sun Feb 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7191236· OSTI ID:7191236

Hemachalam, K

Procedures are described for making superconducting tapes and wires containing filments of the A-15 compound, Nb/sub 3/Sn, by powder metallurgy techniques. The Nb/sub 3/Sn filaments, typically 1-5 m thick, are formed by a short heat treatment. The effects of process variables on the microstructure of the tapes and wires were investigated. Microstructural aspects were examined by optical metallography and transmission electron microscopy. A pulsed field technique was used to determine the critical current density, J/sub c/, at 4.2/sup 0/K as a function of transverse magnetic field up to 170 kG. Satisfactory agreement was oserved between these results and data obtained under steady fields of up to 100 kG. The J/sub c/ of the conductors are related to their individual filament morphologies resulting from the different thermo-mechanical histories. The effect of heat treatment conditions on critical current and transition temperature, T/sub c/, is presented. Through process modifications, optimal values or ranges are developed for the metallugical variables in order to maximize the superconducting properties. The inductively measured T/sub c/ of the conductors is about 17.9 +- 0.1/sup 0/. The values of J/sub c/ for the wires computed on the basis of Nb/sub 3/Sn and niobium matrix are 2.3 x 10/sup 5/ A/cm/sup 2/ at a transverse pulse field of 50 kG, 1.1 x 10/sup 5/ A/cm/sup 2/ at 100 kG and 7.5 x 10/sup 4/ A/cm/sup 2/ at 150 kG.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7191236
• Report Number(s): LBL-4181
• 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
ALLOY SYSTEMS
ALLOYS
BINARY ALLOY SYSTEMS
CRITICAL CURRENT
CRYSTAL STRUCTURE
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
INTERMETALLIC COMPOUNDS
MAGNETIZATION
METALLOGRAPHY
METALLURGY
MICROSTRUCTURE
NIOBIUM ALLOYS
PHYSICAL PROPERTIES
POWDER METALLURGY
SINTERING
SUPERCONDUCTING WIRES
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TRANSITION TEMPERATURE
VERY LOW TEMPERATURE
WIRES