The mechanical deformation of BiSrCaCuO/Ag composites made by the powder-in-tube method is a multi-step process. The main difficulty is that the mechanical properties of the ceramic powder are very different from 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, drawing and extrusion are also presented. The term 'freedom parameter', f , is introduced to illustrate the influence of various constraint factors on the mass-flow behaviour. Simple pictures including mass redistribution and the powder-flow model are presented for interpreting the plastic deformation process of the composites. Experimental results are reviewed and our proposed pictures and models are applied for discussion.

Ag sheathed Bi-2223 multifilament tapes with filament numbers of 19, 37, 55, and 85 were produced by the powder-in-tube method. Enhanced tape performance has been achieved by optimisation of the processing conditions. Key factors are addressed that include elimination of the 2212 phase, improving grain connectivity through reducing the 2201 phase and alkaline earth cuprate phases, increasing superconductor core density as well as enhancing current contribution from edge filaments. A high Jc of 50 kA/cm2 with an IC of 42 A has been achieved reproducibly in 19 filament tapes with dimensions of 0.16x2.8 mm2 and silver/superconductor ratios of 4.4:l. By reducing the silver ratio, a Je of 14 kA/cm2 with an IC of 48 A has been obtained in 55 filament tapes and an IC of 84 A has been obtained in a tape with dimensions of 4x0.23 mm2. A record Jc of more than 30 kA/cmZ with an IC of 32 A was achieved in 250 metres long standard tapes. A 1250 m long pure Ag sheathed tape and an 1100 m long Ag alloyed tape have been produced with a Jc of higher than 25 kA/cm2 by using optimised process parameters.

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