Artificial Pinning Center Niobium Titatium Superconductors with Optimal Overall Compositions

这个小企业创新研究第一阶段项目开发了具有人工钉接中心的NbTi超导体，在性能和成本方面具有最佳的组成。Supercon公司开发了一项专利技术，通过人工钉住中心法（APC）制造NbTi超导体，通过纯金属的部分扩散，将Nb和Ti金属的交替层组装成超导灯丝。它使人们能够独立控制灯丝的有效成分以及非超导相（钉接中心）的厚度和间距。传统的NbTi复合材料制造在大多数应用中使用- Nb-47 wt. % Ti。原则上，Supercon APC方法可以制造几乎任何有效整体成分的复合材料。邻近效应被认为限制了实际的NbTi合金成分与工业上有用的Tc和Hc2在40至65 wt. %的Ti范围内。文献中报道的大多数APC导体的总体组成在该范围的富铌一侧。因此，减少了Hc2，并且比传统合金的原材料成本增加。这项工作是建立在Supercon现有的APC制造经验的基础上，优化新的复合材料，使其具有适合特定应用磁场范围的不同灯丝成分，同时最大限度地减少铌含量，从而降低成本。第一阶段的技术目标是了解成分（相对Nb和Ti层厚度）和第二相体积分数（热处理条件）的独立变化如何影响APC - NbTi超导复合材料的显微结构、机械和电性能（Jc和Hc2）。

This Small Business Innovation Research Phase I project develops NbTi superconductors with artificial pinning centers with an optimal composition in terms of performance and cost. Supercon has developed a patented and proven process for the manufacture of NbTi superconductors using an artificial pinning center approach (APC), which assembles alternate layers of Nb and Ti metals to form a superconducting filament through partial diffusion of the pure metals. It allows one to have independent control of the filament effective composition as well as both the non-superconducting phase (pinning center) thickness and spacing. Conventional NbTi composite manufacturing uses- Nb-47 wt. % Ti for most applications. In principle, the Supercon APC approach can fabricate composites with filaments of almost any effective overall composition. The proximity effect is thought to limit practical NbTi alloy compositions with industrially useful Tc and Hc2 to within the range of 40 to 65 wt. % Ti. Most APC conductors reported in the literature have an overall composition on the Nb rich side of this range. As a result, the Hc2 is reduced, and the cost of the raw materials is increased over a conventional alloy. This proposed work builds upon existing APC manufacture experience at Supercon to optimize new composites with different filament compositions suitable for specific applied magnetic filed ranges, while minimizing the Nb content and therefore cost in each case. The technical objective of the Phase I effort is to understand how independently varying both the composition (relative Nb and Ti layer thickness) and the second phase volume fraction (thermal processing conditions) effect the microstructural, mechanical, and electrical properties (Jc and Hc2) of APC NbTi superconducting composites.