Masahiro Kitada1 and Toshio Doi1
1Central Research Laboratory, Hitachi Ltd., Kokubunji
Applied magnetic field (H)-critical current density (Jc) characteristics of rolled Nb-60Ti-5Zr sheets aged at 300° ∼ 500°C were measured at 4.2°K in order to examine the anisotropic effect. The results are as follows:
(1) The most suitable heat treatment to increase the magnitude of Jc of the sheets is ageing at 300° or 350°C for at least about 500 or 100 hr, respectively. For the sheets aged at 350°C for 125 hr, the critical current densities Jc(||) and Jc(⊥), which correspond to the rolled planes parallel and perpendicular to the direction of an applied magnetic field, are determined as 1.1 × 105 and 5.8 × 104 A/cm2 at 70 kOe and 3.7 × 104 and 1.8 × 104 A/cm2 at 90 kOe, respectively.
(2) In case of ageing at 400° ∼ 500°C, the anisotropic effect of H-Jc characteristics (the ratio of Jc(||) to Jc(⊥)) increases with increasing ageing temperature.
(3) The peak effect is observed in the H-Jc(⊥) characteristics of the sheets and depends upon the ageing temperature and time, while it is not shown in the H-Jc(||) characteristics.
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