The aim of this article is to present a three-dimensional (3D) simulation based on Voronoi tessellation, used to assess the strain dependence of the superconducting critical properties of inhomogeneous polycrystalline Nb₃Sn at the microstructural level. To support this objective, we first present a polycrystalline model with equiaxed grains used to analyze the relationship between the polycrystalline structure and the strain response. We analyze the Young’s moduli of Nb₃Sn at different temperatures with random and preferential polycrystalline orientations, and the relation between the Young’s modulus of polycrystalline Nb₃Sn and spontaneous tetragonal transformation is discussed. The results indicate that the elastic properties (Young’s modulus, stress/strain field) of polycrystalline Nb₃Sn are mainly associated with ambient temperature and phase transition and are affected by the grain orientation. Meanwhile, an estimation-based model for the superconducting critical properties of single-crystal Nb₃Sn is proposed. This model is based on changes in the electron density of states and phonon frequency induced by strain. The results calculated by the estimation-based model are consistent with the experimental data and the values calculated according to first principles. The change in the strain-induced superconducting properties of polycrystalline Nb₃Sn is analyzed by combining the numerically simulated strain field of the polycrystal with the estimation-based model of single-crystal Nb₃Sn. Compared to ideal single-crystal Nb₃Sn, the superconducting critical temperature of the polycrystalline Nb₃Sn superconductor has a higher strain sensitivity, which is related to the non-uniformity of the strain field of the polycrystal.

本文的目的是提出基于 Voronoi 镶嵌的三维 (3D) 模拟，用于评估非均匀多晶 Nb ₃ Sn 在微观结构级别的超导临界特性的应变依赖性。为了支持这一目标，我们首先提出了一个具有等轴晶粒的多晶模型，用于分析多晶结构与应变响应之间的关系。我们分析了具有随机和优先多晶取向的 Nb ₃ Sn 在不同温度下的杨氏模量，以及多晶 Nb ₃的杨氏模量之间的关系讨论了 Sn 和自发四方相变。结果表明，多晶Nb ₃ Sn的弹性性能（杨氏模量、应力/应变场）主要与环境温度和相变有关，并受晶粒取向的影响。同时，提出了一种基于估计的单晶 Nb ₃ Sn超导临界特性模型。该模型基于由应变引起的电子态密度和声子频率的变化。基于估计的模型计算的结果与实验数据和根据第一性原理计算的值一致。多晶Nb ₃应变诱导超导性能的变化通过将多晶的数值模拟应变场与基于估计的单晶 Nb ₃ Sn模型相结合，对 Sn 进行了分析。与理想的单晶Nb ₃ Sn相比，多晶Nb ₃ Sn超导体的超导临界温度具有更高的应变敏感性，这与多晶应变场的不均匀性有关。