CRUSHING AND RECOVERY OF PLATELET GRAINS DURING THERMOMECHANICAL TREATMENT IN AG BI-2223 COMPOSITE/

The crushing and the recovery of superconducting grains during thermom echanical treatment were investigated for Ag/BSCCO composite prepared by the powder-in-tube method. It was observed that the platelet Bi-221 2 and Bi-2223 grains were crushed into small fragments of submicron si ze. It was observed that two types of grain having wavy and straight b oundaries existed for the specimen annealed at 840 degrees C for 25 an d 50 h. It seems that the grain recovery proceeded, at the intermediat e stages of grain growth, in two ways: the coalescence between neighbo ring grains having small-angle grain boundaries and grain growth consu ming the neighboring grains consisting of high-angle grain boundary. I t is considered that the wavy grain boundaries were straightened throu gh the grain growth process via the intermediate process of grain coal escence.