Abstract：Quench of a Nb3Sn superconductor is an important phenomenon in the operation of superconducting magnet equipment. It is a transient process that the superconductor transforms from superconducting phase to normal phase. In the Nb3Sn material’s application in the construction of the high-field-superconducting-magnet, the quench is accompanied by the instantaneous drastic change of the mechanical, thermal and electrical parameters because of the high energy storage density. During a quench, the superconducting phase transition is accompanied by the abrupt change of elastic properties of Nb3Sn. The study of this change is the key to the microscopic and multiscale modelling of the stress arising from the superconducting-normal transition. In this paper, the first-principle calculation method is used to calculate the variation of the elastic constants with temperature, and the results show that due to the lack of the consideration of the effect of the variations of the special electronic band structure of Nb3Sn with the ambient temperature, the elastic constants of Nb3Sn, extrapolated from 0K to the finite temperature based on the quasi-static approximation method, show qualitative difference between the calculations and the experimental observations. Then, based on the function of lattice free energy, an analytical model is given to describe the variation of the elastic properties of cubic Nb3Sn single crystal with temperature. The model predictions are qualitatively consistent with the experimental results, and an analytical description of the elastic properties of Nb3Sn single crystal during the superconducting phase transition is given. The results of the study will contribute to the development of the modelling and numerical simulation of the stress generating by the quench, and lay a foundation of the safety analysis of the superconducting magnets.
2022, Vol. 43 
