Whisker/matrix interface and microstructure of MgO-whisker reinforced (Bi, Pb)2Sr2Ca2Cu3Ox high-temperature superconducting composite

Abstract

In this paper, a comprehensive study of the microstructure and the whisker/matrix interface of a (MgO)w/BPSCCOhigh-temperature superconducting composite is reported. The bulk MgO-whisker reinforced HTS BPSCCO (2223) composite was fabricated using a recently developed solid-state processing method. The (MgO)w/BPSCCO composite has been demonstrated to possess excellent combined superconducting and mechanical properties. The favorable microstructure of the HTS BPSCCO (2223) matrix and the (MgO)w/BPSCCO interfacial properties are recognized to be the critical material parameters governing electric and mechanical performance of the HTS composite. Effects of detailed microstructure variables on superconducting properties of the composite are addressed, including the aspect ratio and the orientation of MgO whiskers, structure, and texturing of the BPSCCO matrix phase, and the (MgO)w/BPSCCO interfacial microchemistry. The results obtained reveal unique characteristics of the reinforcing MgO whiskers dispersion, distribution, and orientation in the HTS composites. The evolution of the microstructure and texture of thematrix BPSCCO grains has also been studied in the process of repeated hot-pressing and annealing heat treatment. The thermodynamic compatibility and microchemistry in the MgO whisker and BPSCCO interfaceare also examined.