未来的聚变核能和第四代先进核能系统都面临高强度中子辐照导致的材料性能退化问题。因此，发展新型的抗辐照材料已经成为发展核能系统的关键之一。近年发展起来的基于多主元的高浓度固溶体合金表现出优异的力学性能和抗辐照特性，很有希望成为新一代的抗辐照核能材料。但是，其抗辐照的内在机制还不是很清楚，特别是多种主元金属元素共存条件下的位错性质及其与辐照缺陷的相互作用。本项目拟采用多尺度的计算模拟手段研究面心立方结构的多主元合金中位错与缺陷的相互作用及其演化。通过模拟多主元合金中堆垛层错能在无序化原子排布下的分布，找出该分布与不同元素之间的关系，理解扩展位错在不同合金中的展宽行为。在此基础上，本项目将研究多主元合金中位错引起的能量以及应力场分布，并计算缺陷在该应力场中的能量状态。进一步地，本项目将研究缺陷与位错在不同温度下的相互作用，并考虑缺多主元合金中陷优先扩散特性导致的元素在位错附近富集的影响。

Materials degradation due to high-flux neutron irradiation is one of the major problems facing the development of advanced nuclear systems in the future, including nuclear fusion reactors and Generation-IV nuclear fission reactors. Therefore, to develop irradiation-resistant nuclear materials has become a key issue. Recently, concentrated solid-solution alloys composed of multiple principal elements, also referred to as high-entropy alloys with more than five components, have demonstrated unusual mechanical and irradiation performance. Although lots of experiments have shown that these alloys possess promising irradiation resistance, the underlying mechanism remains unclear, especially for the interactions between dislocations and irradiation-induced defects. In this project, we propose to study the dislocation-defect interaction in multicomponent alloys through multi-scale simulation techniques. We will first calculate the stacking fault energy distributions in multicomponent alloys in order to establish the relationship between stacking fault energy distribution and the arrangement of different elements surrounding the stacking fault. The relationship will be utilized to clarify the fluctuations observed in the dissociation distance of perfect dislocations in face-centered cubic (fcc) multicomponent alloys. Based on these results, we will study the strain energy and stress filed induced by edge and screw dislocations in selected fcc multicomponent alloys. The energetics of defects located around the dislocation will be calculated. Finally, we will study the kinetics of defects around the dislocation to reveal the interaction between defects and dislocations at finite temperatures. The preferential diffusion of defects in multicomponent alloys will be further investigated by tuning atomic concentration (short-range order parameter) around dislocations.