Crystallization of A15 Nb sub 3 Ge from the amorphous state

Journal Article · Thu Mar 01 04:00:00 EST 1990 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1990.0478· OSTI ID:7122368

Wardak, M; Clapp, M T ^[1]

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1. Department of Mechanical Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (USA)

The critical current density J{sub {ital c}} of superconductors is strongly dependent on microstructure. The microstructure and crystallization of amorphous Nb{sub 75}Ge{sub 24.5}B{sub 0.5} melt spun ribbons were studied as a function of 24-h anneals between 680 and 860 {degree}C. Metastable A15 was formed with a composition close to that of the starting amorphous material. As the temperature increased from 680 to 720 {degree}C, crystallization remained nonuniform and the average grain size decreased from 130 nm to 60 nm. Between 740 and 800 {degree}C crystallization was uniform and the average grain size was constant at 30 nm. Above 820 {degree}C grain growth occurred. In order to have high J{sub {ital c}}'s a uniformly crystallized small-grained material is desirable.

• OSTI ID: 7122368
• Journal Information: Journal of Materials Research; (USA), Journal Name: Journal of Materials Research; (USA) Vol. 5:3; ISSN JMREE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
ANNEALING
BETA-W LATTICES
BORIDES
BORON COMPOUNDS
CRITICAL CURRENT
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALLIZATION
CURRENTS
ELECTRIC CURRENTS
GERMANIUM BORIDES
GERMANIUM COMPOUNDS
GRAIN SIZE
HEAT TREATMENTS
HIGH TEMPERATURE
MICROSTRUCTURE
NIOBIUM BORIDES
NIOBIUM COMPOUNDS
OPTIMIZATION
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
REFRACTORY METAL COMPOUNDS
SIZE
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE