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Hot Deformation of Metallic Precursor Bi-2223 and Y-123 Materials in a Silver Matrix by Hot Rolling and Drawing

IP.com Disclosure Number: IPCOM000028011D
Publication Date: 2004-Apr-19
Document File: 1 page(s) / 56K

Publishing Venue

The IP.com Prior Art Database

Abstract

This paper contains the results of two hot processing methods for either Bi-2223 or Y-123 Metallic Precursor (MP) materials in multifilamentary wires with a silver matrix. Both deformation techniques can lead to high performance HTS tapes through a sound deformation of the superconductor in the metallic state, followed by the usual oxidation step to form the superconducting Bi-2223 or Y-123 oxide.

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Hot Deformation of Metallic Precursor Bi-2223 and Y-123 Materials in a Silver Matrix by Hot Rolling and Drawing

     This paper contains the results of two hot processing methods for either Bi-2223 or Y- 123 Metallic Precursor (MP) materials in multifilamentary wires with a silver matrix. Both deformation techniques can lead to high performance HTS tapes through a sound deformation of the superconductor in the metallic state, followed by the usual oxidation step to form the superconducting Bi-2223 or Y-123 oxide. The yield strength of the MP varies more rapidly with temperature than that of silver, and relatively small changes in temperature can lead to unwanted changes in ductility. To gain more insight in the hot deformation mechanisms the compressive stress-strain relationship at temperatures that are routinely used for hot deformation is measured.

      The hot rolling and drawing deformation techniques are used in combination with hot extrusion (hydrostatic and ram extrusions). Hot extrusion, in particular the upscaled commercial scale ram extrusion, allows very high extrusion ratios and is a prime deformation process for MP materials. For an accurate control of the final tape dimensions one needs to be able to hot draw the wires to the exact size which, after hot rolling, will yield the final desired tape dimensions. Hot drawing was therefore developed as a suitable method for the sound reduction of multifilamentary MP wires. Hot drawing could be made to work quite well, provided that the yield strength of the matrix is well matched to that of the MP while the MP is a ductile state. For Bi-...