Experimental study on strain sensitivity of Internal-Tin Nb3Sn superconducting strand based on non-destructive technology

Fracture of brittle filaments plays a crucial role in significant degradation of critical current density of multifilamentary Nb3Sn strand. Recent researches of distribution of filament factures mostly depend on photographic analysis with SEM or TEM. However, it is hard to obtain spatial distribution of filament fractures in the mulitifilamentary Nb3Sn strand. In addition, almost unavoidable filament fracture is introduced during the sample preparation procedure and it causes deviation of filament fracture distribution. X-ray microtomography is a noninvasive, non-destructive method, which allows determination and the discrimination of internal features without destructing the sample. It is widely used as a non-destructive test technology for its high penetrability and high resolution. This present work investigated filament fracture of two types of Nb3Sn strands under different tensile strains by high energy X-ray. The influence of tensile strain on the filament fracture behavior was investigated and the results will be expected to provide reference for optimization of multifilamentary Nb3Sn strand, conductor and magnet design.

Automated summary

Fracture of brittle filaments is crucial in degrading critical current density of multifilamentary Nb3Sn strands. X-ray microtomography is a non-destructive method used to investigate filament fracture behavior under different tensile strains, providing reference for optimization of multifilamentary Nb3Sn strands.