Metallurgy, fabrication, and superconducting properties of multifilamentary Nb/sub 3/Al composites

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7230932

Hafstrom, J W

The control of metallurgical structure during fabrication that will improve the superconducting properties of multifilamentary, aluminium-stabilized, Nb/sub 3/Al composites is described. Composites are fabricated by placing niobium rods in an aluminum matrix, and then drawing to wire. Nb/sub 3/Al is formed at temperatures exceeding 1800/sup 0/C for about 5 s and ordered at 750/sup 0/C for 48 h. A critical current, J/sub c/(H), in excess of 10/sup 5/ A/cm/sup 2/ (F/sub p/ approximately equal to 7 x 10/sup 8/ dynes/cm/sup 3/) at 7 T and a T/sub c/ to 18.2 K are obtained. Attempts to improve J/sub c/(H) by controlling the grain size in the Nb/sub 3/Al diffused layer are discussed. Precipitates, arising from the addition of carbon during Nb/sub 3/Al layer growth, do not appear to be effective as grain-boundary or flux pinners. When 1 percent Zr is added to the Nb, the growth of the Nb/sub 3/Al layer is accelerated, T/sub c/ is lowered and J/sub c/(H) is not significantly improved. J/sub c/(H) rapidly decreases with an increase in Nb/sub 3/Al or (Nb-Zr)/sub 3/Al layer thickness, d. J/sub c/(H) is independent of d in composites with d greater than or approximately equal to 1.5 ..mu..m. In general, the Nb/sub 3/Al grain size appears comparable to d for d less than or equal to 1 ..mu..m. Significant improvement of J/sub c/(H) for Nb/sub 3/Al superconducting composites reacted at temperatures above 1800/sup 0/C (to achieve T/sub c/ greater than 17 K) is achieved only by maintaining the layer thickness well below d approximately equal to 1.0 ..mu..m.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7230932
• Report Number(s): CONF-760829-51
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360104* -- Metals & Alloys-- Physical Properties
360301 -- Composite Materials-- Preparation & Fabrication-- (-1987)
360304 -- Composite Materials-- Physical Properties-- (-1987)
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM ALLOYS
COMPOSITE MATERIALS
CRITICAL CURRENT
CRITICAL FIELD
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
MAGNETIC FIELDS
METALLURGY
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
SUPERCONDUCTING COMPOSITES
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE