The effect of annealing and mechanical deformation on the grain alignment of (Bi,Pb)(2)Sr2Ca2Cu3O8+x superconductors

Mechanical deformation and annealing treatments are widely used in the processing of (Bi,Pb)(2)Sr2Ca2Cu3O8+x superconductor wires to produce grain alignment. Annealing texture has been suggested as one of the possible grain alignment mechanisms, but very little experimental evidence and understanding have been reported. The present paper reports a detailed study of the relationships of mechanical deformation, annealing, grain alignment and grain size in Ag-sheathed Bi2223 tapes. Results indicated that (1) the (00l) grain alignment on the specimen surface after annealing is considerably higher than before annealing, (2) the surface grain alignment decreases with the increasing mechanical deformation, and (3) the grain size after recrystallisation decreases with the increasing mechanical deformation. Based on the experimental results, the mechanisms of annealing/recrystallisation induced grain alignment were discussed. This understanding can be used to control the microstructure of high temperature superconductors in order to improve their transport properties.