Reaction induced texture of (Bi,Pb)2Sr2Ca2Cu3O10+δ /Ag composite conductors

Abstract

A considerable body of evidence collected on silver-sheathed (Bi,Pb)2Sr2Ca2Cu3O10+δ (Bi-2223/Ag) composite conductors heat treated without any additional rolling or pressing (beyond fabrication of the initial composite) has revealed that significant texturing of the Bi-2223 grains occurs as the Bi-2223 formation reaction takes place. During heat treatment, Bi-2223 is produced via a reaction between Bi-2212 and second phases in the core of the composite. As the Bi-2223 forms, it develops texture by what appears to be a grain growth mechanism. These concurrent processes ultimately result in a well-textured, single-phase conductor even when no additional rolling or pressing is done to the initial composite. This observation raises important questions about the relative contributions of the heat treatment and deformation steps to texture development during conventional oxide-powder-in-tube processing of Bi-2223/Ag composite conductors.