Actions for EFFECTS OF ISOTHERMAL ANNEALING ON THE MICROSTRUCTURE AND ON THE SUPERCONDUCTIVITY OF TWO AMORPHOUS BERYLLIUM-ZIRCONIUM ALLOYS

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EFFECTS OF ISOTHERMAL ANNEALING ON THE MICROSTRUCTURE AND ON THE SUPERCONDUCTIVITY OF TWO AMORPHOUS BERYLLIUM-ZIRCONIUM ALLOYS

Author
HEH, JIUN-PEIR
Physical Description
122 pages
Additional Creators
Pennsylvania State University
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Summary
This thesis presents the measurement results of isothermal annealing experiments on the amorphous alloys Be-Zr (30 a/o and 40 a/o Be), in which the critical current density, J(,C), was correlated with changes in the microstructure. The superconducting transition temperature, T(,C), and upper critical magnetic field, H(,C2), are less structure-sensitive parameters. However, they were also monitored in the course of this study. In addition, the superconducting parameters such as the zero temperature coherence length, (xi)(0), and the Ginzburg-Landau (GL) parameter, (kappa), etc. were calculated on the basis of the measured quantities, T(,C), the electrical resistivity, (rho), and the temperature gradient of the upper critical magnetic field at temperatures near T(,C), i.e., (dH(,C2)/dT)(,T=T(,C)). The microstructure of the studied samples was determined by x-ray, transmission electron microscopy (TEM), scanning electron microscopy (SEM) observations. The former two techniques were utilized to search for evidence of crystallization whereas the later provides information of the surface condition for samples used in this investigation.
Results exhibiting the influence of isothermal annealing on microstructure and on superconductivity are: (1) electron micrographic evidence for the development of phase separation occurred in the cases of samples annealed for 1 hour and 2 hours at 100 K below their glass transition temperatures, T(,g), (2) T(,C) and H(,C2) of the annealed samples are always found to decrease below their values of the initially unaged conditions, and (3) strong reductions of the pinning force densities, F(,p), resulted, which suggest that pinning by inhomogeneities in composition and/or strain fields rather than by second phase precipitates and/or surface roughness appears to be likely.
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Dissertation Note
D.ED. The Pennsylvania State University 1985.
Note
Source: Dissertation Abstracts International, Volume: 46-09, Section: B, page: 3086.
Part Of
Dissertation Abstracts International
46-09B
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