Correlation between the Critical-current Anisotropy and Microstructure of ex-situ Processed MgB2 Tapes Using Carbon-substitution Treatment

Correlation between the critical current anisotropy and the textured microstructure of the ex-situ processed MgB2 tapes with the Fe sheath was studied to obtain basic data related to the commercial application of the ex-situ processed MgB2. Ex situ processed MgB2 tapes were fabricated using newly developed technique to substitute carbon for boron in the MgB2 compound through the ex situ route. These MgB2-xCx tapes showed comparable critical current anisotropy to that of pure MgB2 tapes, but in higher magnetic fields because of their higher irreversible critical field than the pure MgB2 tapes. The x-ray pole figure data show that the tape core texturing of the MgB2-xCx tapes was moderate, but it was a slightly higher degree than that of the pure MgB2 tapes. This result was consistent with results of the critical current anisotropy.