Abstract In the present work, microstructural and microchemical of Nb3Sn strands with the internal tin process produced by the Western Superconductor Technology co., Ltd (WST) and Oxford Instruments co., Ltd (OST) were analyzed. The internal 3D-view of two Nb3Sn strands were detected with a (sub-)micrometric resolution in a non-invasive, non-destructive way, i.e. high-resolution 3D X-ray micro tomography. The distribution of filaments and voids induced by the functional heat treatment of two strands were investigated. The elements distribution after heat reaction of two strands was investigated through elemental mapping by scanning electron microscope (SEM) and energy dispersive X-ray analysis. The filaments of the WST Nb3Sn strand distributed uniformly, whereas the filaments separated with clear copper boundary among filaments. However, the filaments of the OST Nb3Sn strand have serious overlap phenomenon and the copper isolation interface was not clear among filaments. In order to investigate the distinction of microstructure, the selected area electron diffraction was also performed by transmission electron microscopy (TEM) and the results indicated that obvious impurities were observed in the Nb3Sn phase of the WST strand compared to the OST strand.

中文翻译：

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两种内锡工艺Nb3Sn丝的成分和微观结构对比研究

摘要 在目前的工作中，分析了西方超导技术有限公司 (WST) 和牛津仪器有限公司 (OST) 生产的内锡工艺 Nb3Sn 股线的显微结构和微化学。两个 Nb3Sn 链的内部 3D 视图以（亚）微米分辨率以非侵入性、非破坏性的方式检测，即高分辨率 3D X 射线显微断层扫描。研究了由两股线的功能热处理引起的细丝和空隙的分布。通过扫描电子显微镜（SEM）和能量色散X射线分析的元素分布研究了两条链热反应后的元素分布。WST Nb3Sn 股线的细丝分布均匀，而细丝之间以清晰的铜边界分开。然而，OST Nb3Sn股线的细丝重叠现象严重，细丝间铜隔离界面不清晰。为了研究微观结构的区别，还通过透射电子显微镜（TEM）进行了选区电子衍射，结果表明与 OST 钢绞线相比，在 WST 钢绞线的 Nb3Sn 相中观察到明显的杂质。