Method of forming superconductive articles by hydrostatic extrusion

A method for making a superconducting article, comprising the steps of:

• a) providing a hollow cylinder comprising cladding material;
• b) providing core material comprising metallic oxide superconductor material, the metallic oxide superconductor material being characterized by a fused density;
• c) enclosing the core material within the cylinder;
• and
• d) elongating the cylinder and core material such that a first cross sectional area is associated with the core material just prior to the elongating step, a second cross sectional area is associated with the core material after the elongating step, and the first cross sectional area is greater than the second cross sectional area, characterized in that
• e) the core material is substantially free of organic materials and elemental carbon;
• f) the elongating step comprises hydrostatically extruding the cylinder and the core material such that a composite extrudate, comprising core material and cladding metal, is produced, and the first cross sectional area is at least 30 times the second cross sectional area;
• g) the core material comprises at least one sintered slug or pellet, the slug or pellet having an equivalent density that is at least 55% of the fused density of the metallic oxide superconductor material;
• h) the method further comprises, before the hydrostatic extrusion step, the step of heating the core material to a temperature which, at the commencement of the hydrostatic extrusion step, is at most about 450.degree. C.;
• and
• i) the cladding material comprises a dispersion hardened metal or a dispersion hardened metal alloy.