The co-extrusion of metal-sheathed high-temperature superconductors

The co-extrusion of copper cans containing Ag-clad high-temperature superconductor (HTS) cores using a direct extrusion technique was investigated. Composite rods were produced by simultaneous cladding and consolidation of the superconducting material, however, a range of deformation behaviour occurred, including core and sleeve fracture, non-uniform wavy core and sound flow. The flow patterns varied consistently as the initial core diameter (Dci) and reduction ratio (R) were varied, allowing domains of specific deformation behaviour to be defined. The large variation in flow behaviour was also attributed to stiffness mismatch between the HTS core and the cladding metal.