Superconductivity and physical metallurgy

Abstract

After a brief summary of the historical development of the field of superconductivity and the background required for the topics treated in the present paper, some of the relationships between superconductivity and physical metallurgy are discussed. These are mainly in two areas: i) The distribution of magnetic flux in super conductors may show fine structures (boundaries between normal and superconducting regions in the intermediate state of type-I superconductors; quantized flux-lines in the Shubnikov phase of type-II superconductors) on such a scale that they interact strongly with the metallurgical microstructure of the superconducting materials, such as grain boundaries, dislocations, precipitates, and so forth. ii) Ideally, the flux-lines in a type-II superconductor form a two-dimensional lattice (Abrikosov lattice). The decoration technique of Trauble and Essmann has permitted the direct observation of these flux-lines lattices and has revealed that they contain a rather high density of defects. Most of them are known from the studies of defects in crystals, such as grain boundaries, dislocations, stacking faults, and vacancy and interstitial lines, but also disclinations, which were predicted by theory but have not yet been observed in metals, were investigated.