A15 superconductors through direct solid-state precipitation: V/sub 3/Ga and Nb/sub 3/Al

Technical Report · Mon Sep 01 04:00:00 EDT 1980

DOI:https://doi.org/10.2172/6769991· OSTI ID:6769991

Hong, M

A solid-state precipitation process was used to prepare superconducting tapes containing an A15 phase, V/sub 3/Ga or Nb/sub 3/Al, in a ductile niobium or vanadium containing BCC matrix. Ingots weighing as large as 30 to 50 gms of V-(14 approx. 19 at. %) Ga and Nb-(13 approx. 22 at. %) Al were prepared by arc-melting, homogenized, quenched, warm-rolled over 99% into tape, and aged at temperatures in the range 600/sup 0/C to 1000/sup 0/C to precipitate the superconducting A15 phase. The features demonstrated by the process are very attractive for practical applications. In the V-Ga system, transmission electron microscopy (TEM) studies revealed the A15 precipitates in an elongated form. However, for the Nb-Al samples, deformed and aged at 750/sup 0/C, TEM studies revealed A15 precipitation in fine equi-axed particles which formed as a semi-continuous network over sub-grain boundaries formed by the recovery of deformation-induced dislocations. In the V-Ga system, the maximum critical transition temperature (approx. 15 K) was found in materials aged at temperatures of 750/sup 0/C or below. At these aging temperatures the T/sub c/ initially increased with aging time and passed through a distinct maximum. The source of the exceptionally high T/sub c/ is discussed. In the Nb-Al system, the aging response of the T/sub c/ of the tested samples was somewhat different; the T/sub c/ increased with aging time to a plateau, and then increased again to a second plateau. The maximum T/sub c/ measured was approx. 17 K. Promising high-field overall critical currents were obtained in the Nb-Al system (overall J/sub c/ approx. 10/sup 4/ A/cm/sup 2/ in a magnetic field of 140 KG at 4.2 K).

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6769991
• Report Number(s): LBL-11021
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
360604 -- Materials-- Corrosion
Erosion
& Degradation
656102* -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM ALLOYS
BETA-W LATTICES
CRITICAL CURRENT
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
FABRICATION
GALLIUM ALLOYS
HARDENING
HIGH TEMPERATURE
INTERMETALLIC COMPOUNDS
MICROSCOPY
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
PRECIPITATION HARDENING
SUPERCONDUCTIVITY
TABLES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VANADIUM ALLOYS
VANADIUM BASE ALLOYS