Evidences on reformation of (Bi,Pb)-2223 superconducting phase after complete peritectic melting

摘要

It is demonstrated that it is possible to reform in air atmosphere considerable amounts of (Bi,Pb)-2223 phase within Ag environment after complete peritectic melting of this phase. The key feature of here proposed complete melting-reformation process is the minimization of Pb-losses, where only about 1.57 wt. percent of total Pb content was lost over whole process. Therefore, an adequate melting temperature slightly above the peritectic melting onset of the (Bi,Pb)-2223/Ag composite and slow cooling (0.1 deg C/min) conditions should be used in order to keep the system in near-equilibrium conditions. This new route for (Bi,Pb)-2223 formation within Ag environment, including the participation of a thermodynamically stable liquid, should overcome some microstructural problems present nowadays in the conventionally prepared (Bi,Pb)-2223/Ag tapes, such as voids, cracks and bad grain connectivity.