CRYOGENIC-TEMPERATURE AND ROOM-TEMPERATURE MECHANICAL-BEHAVIOR OF AN AL2O3-FIBER-REINFORCED HIGH-TEMPERATURE SUPERCONDUCTING (BI,PB)(2)SR2CA2CU3OX CERAMIC-MATRIX COMPOSITE

Recently, an investigation has been reported on the processing study o f a continuous Al2O3-fibre-reinforced, lead-doped Bi2Sr2Ca2Cu3OX (BPSC CO) high-temperature superconducting (HTS) composite. In this paper, c ryogenic- (77 K) and room- (293 K) temperature mechanical behaviour of the Al2O3-fibre/BPSCCO-matrix composite is studied. Tensile and notch ed fracture experiments are conducted on both monolithic BPSCCO and Al 2O3/BPSCCO composite specimens fabricated in various hot-pressing cond itions. Mechanical properties of the HTS materials are found to be str ongly dependent upon processing parameters and test temperatures. Sign ificantly higher stiffness, strength and toughness of the Al2O3/BPSCCO HTS composite are obtained than those of the monolithic BPSCCO at bot h room and cryogenic temperatures. Owing to the physico-chemical incom patibility and the mismatch of thermomechanical constituent properties between the matrix and the fibres, microscopic thermal stresses devel oped during processing and in the cryogenic environment. These effects are addressed.