Mechanical Response Analysis Of Nb₃Sn Materials At Very Low Temperature-High Pressure/High Strain Rate

Nb₃Sn superconducting material is mainly used to make superconducting magnet with strong magnetic field.In the material application in the high-field magnet design and manufacture,strain-induced superconducting performance degradation of Nb₃Sn is of great importance and significance.In order to reveal the different degradation responses of Nb₃Sn single crystal and Nb₃Sn polycrystal under high hydrostatic pressure,we establish a constitutive relation characterizing the electro-mechanical coupling behavior in Nb₃Sn single crystal.The constitutive relation is based on Maki De Gennes(MDG)relation.By using the relation,we predict the hydrostatic pressure induced critical temperature degradation response of Nb₃Sn polycrystalline superconductor,whose deformation is modeled by polycrystalline finite element method.The predicted results are qualitatively consistent with the experimental observations.The proposed relation can consistently describe the hydrostatic pressure induced degradation responses of both Nb₃Sn single crystal and Nb₃Sn polycrystal.Nb₃Sn superconducting material works in very severe environment.The degradation of superconductivity and the quench process occur in a transient state.By using molecular dynamics simulation,we study the mechanical response of Nb₃Sn single crystal and polycrystal under high pressure and high strain rate.The simulation results reveal the atomic stress distribution of single crystal and polycrystal Nb₃Sn.On the basis of the developed electro-mechincal coupling constitutive relation,we predict the degradation performance of critical temperature.The molecular dynamics simulation results of superconducting critical temperature degradation are in good agreement with those deduced from finite element simulation results and experimental observations.The results are helpful to improve the understanding of the electro-mechanical coupling behavior of Nb₃Sn superconducting material.It lays a foundation for multi-scale characterization on Nb₃Sn properties in extreme serving environment.At the same time,the results can be used to evaluate high field superconducting magnet design and to give insight on how to fabricate superconducting materials with high strain resistance.