Lubrication-Enabled Homogeneous Densification and Morphology Control in Iron-Based Superconducting Tapes

The scalable manufacturing of high-performance iron-based superconducting (IBS) tapes is contingent upon solving two critical challenges in rolling processes: the lack of uniform core densification and the occurrence of cross-sectional distortion known as the saddle-core morphology. Both issues originate from the mechanical incompatibility between the silver sheath and the porous superconducting core, which leads to non-uniform compaction and degraded current transport. Here, we establish a multi-scale finite element model that explicitly couples the elasto-plastic deformation of the silver sheath with the compaction behavior of the superconducting core governed by a modified Drucker-Prager Cap model. The simulations show that high interfacial friction between the silver sheath and the flat roller induces shear dilation and bulging, while low initial core density amplifies strain inhomogeneity. Guided by these mechanisms, we demonstrate that applying interfacial lubrication and optimizing initial packing density and rolling reduction can suppress dilation and enable homogeneous densification. This work delivers essential theoretical insights and practical guidance for the production of high-performance IBS tapes for high-field applications.