Effect of grain boundary deformation on the critical temperature degradation of superconducting Nb3Sn under hydrostatic pressure

Abstract Variation of the critical superconducting properties of Nb3Sn material in terms of mechanical deformation has not been well determined. Fundamental understanding of electromechanical coupling effects is significant in the analysis and construction of high magnetic field superconducting magnet. Considering the microstructure deformation and its inner relationship with normal state resistivity evolution, we developed a consistent description of critical temperature degradation responses of single- and polycrystal Nb3Sn under hydrostatic pressure. The model simulations qualitatively agree with the experimental observations. Based on the polycrystalline finite element method, the analysis carefully examines the role of grain boundary deformation in the critical temperature degradation of superconducting Nb3Sn under high pressure. The grain boundary deformation-related effect is responsible for the obvious degradation differences between polycrystal and single crystal Nb3Sn under the same level of pressure. The results are helpful for understanding the empirical relation presented by the experiment and opens the way for the parameterization of the strain sensitivity of the superconducting Nb3Sn material.