OXIDATION OF METALLIC ALLOYS TO PRODUCE HIGH-T(C)-SUPERCONDUCTING OXIDE AG-MICROCOMPOSITES

A metallurgical/high temperature oxidation method has been developed to produce high T(c) superconductors. Metallic precursor alloys were produced by vacuum melting and rapid solidification. Ag was added to the alloy to improve processing and mechanical properties. These alloys were subjected to controlled oxidation and annealing to convert them into high T(c) superconductors. Bi-Pb-Sr-Ca-Cu-O/Ag superconducting microcomposites with zero resistance at 104-1 10 K were produced in this way. The oxidation kinetics and oxide structure were studied by thermogravimetry, electron microscopy and microanalysis. The formation of the superconducting oxides was studied by establishing a set of temperature-time-transformation (TTT) diagrams. Mechanical deformation was also introduced to produce samples with a textured microstructure and improved J(c) (approximately 10000 A/cm2 at 77 K). The metallic oxidation method has advantages in mass production of superconductors in the forms of long ribbons and coils with improved mechanical properties.