Densification of Bi_<1.8>(Pb)_<0.35>Sr_<1.9>Ca_<2.1>Cu_3O_x and Texture Development through Sinter-Forging

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A technique known as sinter-forging has been used to achieve dense Bi_<1.8>(Pb)_<0.35>Sr_<1.9>Ca_<2.1>Cu_3O_x high-T_c superconducting material with oriented grains. The relationship between the final microstructure and processing conditions was elucidated. Material density and texture increases with the hot-forging pressure and temperature. Grains are elongated with the c-axis oriented approximately parallel to the direction of applied stress. The degree of grain orientation has been quantified using X-ray diffraction and is reported in terms of Lotgering's orientation factors. A maximum orientation factor of 38% was found for processing at 830℃ and 4 MPa in air. The influence of the sintering temperature and atmosphere on the electrical properties has been investigated. After processing at 810℃ and 4 MPa, the sinter-forged materials exhibit superconductivity, according to resistivity measurements, with a T_c (R=0) of 104 K. The critical current density at 77 K increases with increasing bulk density.
社団法人応用物理学会の論文
1993-10-15