THE MECHANICAL DEFORMATION OF SUPERCONDUCTING BISRCACUO AG COMPOSITES/

The mechanical deformation of BiSrCaCuO/Ag composites made by the powd er-in-tube method is a multi-step process. The main difficulty is that the mechanical properties of the ceramic powder are very different fr om those of the Ag sheath. A key parameter is the core density, which changes during mechanical deformation. In this review, basic concepts of the classical mechanical deformation theory are briefly discussed. Simple descriptions of deformation processes like pressing, rolling, d rawing and extrusion are also presented. The term 'freedom parameter', Delta(f), is introduced to illustrate the influence of various constr aint factors on the mass-flow behaviour. Simple pictures including mas s redistribution and the powder-flow model are presented for interpret ing the plastic deformation process of the composites. Experimental re sults are reviewed and our proposed pictures and models are applied fo r discussion.