预时效热处理对Nb46.5Ti超导体临界电流密度的影响

Effect of Preheat Treatment on the Critical Current Density in Nb46.5Ti/Cu Composites

采用高均匀性、低杂质含量的优质 Nb46 .5 Ti (质量分数 ,下同 )合金锭 ,研究了热处理制度对 Nb46 .5 Ti/ Cu多芯超导体临界电流密度的影响。结果表明 :较低温度预时效热处理有利于 Nb Ti超导体中α - Ti沉淀相细化 ,而且分布弥散 ;时效次数越多 ,这种效果就越明显 ,同时时效次数越多 ,α - Ti沉淀相数目及密度也越高 ,从而有利于Nb46 .5 Ti超导体 Jc的提高。另外这种工艺还使多芯 Nb46 .5 Ti/ Cu复合线获得最佳 Jc的最终附加应变减小 ,对多芯复合线的生产具有重要意义。其最高 Jc为 35 0 0 A/ mm2 (4.2K,5 T,判据 0 .1μV/ cm)和 1740 A/ mm2 (4.2 K,8T,判据 0 .1μV/ cm)

High homogenous and low impurity content Nb46 5Ti ingots were used to study the effect of heat treatment on the critical current densities in Nb46 5Ti/Cu multifilamentary composites. The results show that low temperature preheat treatment is beneficial to refining and dispersing the α Ti precipitates in NbTi superconductors. The more cycles of heat treatment, the better effect and the larger density of α Ti preciptites. Finally, the J c  in Nb46 5Ti superconductors has been improved. Moreover, the final strian of Nb46 5Ti/Cu multifilamentary composites can be reduced when preheat treatment is used, which is very important to the commercial manufacture of NbTi/Cu of multifilamentary composites. The highest J c  reaches 3 500A/m\+2(4 2 K, 5 T),and 1 740A/m\+2(4 2 K,8 T) for the preheat treated Nb46 5Ti/Cu composites.