Fabrication of oxide superconducting wire by elongation suppressed rolling.

为了模拟氧化物包覆在银管中的变形，将钇基氧化物超导体包覆在铝管中轧制成带材。研究了道次制度对氧化物型芯变形的影响。轧件横向宽展随道次压下量的增加而增大，随轧前管径的减小而减小。在通常的批量轧制中得到的众所周知的结果，即横向扩展随着辊缝比的增加而增加，在轧制金属管中的氧化物护套时也是如此。当采用每道次压下量较大的道次规程轧制时，沿纵向的芯部分布不均匀变得显著。研究了轧制条件对银包铋基氧化物线材临界电流的影响。通过卫星轧机（伸长抑制轧制，3道次）、非对称轧制（11道次）或常规平轧（3道次）将2 mm厚的带材轧制至1 mm厚（中间轧制），然后通过平轧轧制至0.2mm厚的带材。虽然超导体/银界面不规则，但卫星轧机轧制的带材具有最高的Jc。采用卫星轧机轧制（8道次，30道次，2.5%/道次）或常规轧制（30道次，2.5%/道次）消除了这种不规则性。两个烧结过程之间的机械变形（中间变形）对Jc有显著影响。采用交叉轧制作为中间变形的带材比采用常规轧制作为中间轧制的带材具有更高的Jc。交叉轧制带的晶粒的c轴几乎垂直于带的平面取向，具有关于纵向的轻微旋转分量。常规轧制带的那些也几乎垂直于带的平面取向，但具有关于横向方向的轻微旋转分量。这种质地上的差异似乎引起Jc的差异。

Yttrium-based oxide super conductor sheathed in aluminum tube was rolled into tapes in order to simulate the deformation of oxide sheathed in silver tube. The effect of pass schedule on deformation of oxide core was studied. The lateral spread increases with increasing reduction per pass and with decreasing the diameter of tube before rolling. The well known results obtained in usual bulk rolling that the lateral spread increases with increasing roll gap ratio holds true in rolling of oxide sheathed in metal tube. Non uniform core distribution through longitudinal direction becomes notable when rolled in pass schedule with high reduction per pass. The effect of rolling condition on critical current of silver sheathed Bi-based oxide wire was studied. The tape of 2mm in thickness was rolled to 1mm in thickness (intermediate rolling) by satellite mill (elongation suppressed rolling, 3passes), asymmetric rolling (11passes) or conventional flat rolling (3passes), then rolled to tape of 0.2mm in thickness by flat rolling. The tape rolled by satellite mill exhibited highest Jc, though the superconductor/silver interface was irregular. Application of satellite mill rolling (8passes, 30stages, 2.5%/stage) or conventional rolling (30passes, 2.5%/pass) eliminates this irregularity. The mechanical deformation between two sintering processes (intermediate deformation) exerts a marked effect on Jc. The tape for which cross rolling is adopted as intermediate deformation exhibits higher Jc than that for which conventional rolling is adopted as intermediate rolling. The c axes of the grains of cross rolled tape are oriented nearly perpendicular to the plane of the tape with slight rotating components about longitudinal direction. Those of conventionally rolled tape are also oriented nearly perpendicular to the plane of the tape, but have slight rotating components about transverse direction. This difference in texture seems to induce the difference in Jc.