| YBa₂Cu₃O_(7-x) oxide superconductors was fabricated by sintering process and upsetforging method, respectively, and microstructures and conduction properties were compared. There was no difference in crystal structure between the as-sintered and the upset-forged specimens. The upset-forging enhanced the (001) x-ray reflection presumably due to preferred crystal orientation of the YBa₂Cu₃O_(7-x) superconductor. Furthermore, the grain size of the 123-phase increased as the reduction ratio became larger during the upset-forging. The critical temperature for zero resistivity of both samples was almost the same, i.e., about 90K These results have demonstrated the potential of producing YBa₂Cu₃O_(7-x) superconducting wire or tape effectively using a upset-forging method. The critical current density of the upset-forged sample, however, was lower than that of the sintered one, which fact might be ascribed to microcrack formation during fast upset-forging. |
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