为理解锆合金在核反应堆中的辐照损伤及蠕变的微观电子机制，本工作利用分子动力学方法对α-Zr纳米晶在高温、辐照等不同条件下的拉伸蠕变过程进行了模拟。结果表明：温度、应力、辐照和晶粒尺寸会影响纳米晶α-Zr的蠕变行为，升高温度、增大应力和细化晶粒均会促进蠕变过程的进行。蠕变后体系的微观组织发生显著变化，部分晶粒随蠕变的变形过程而长大，另一些晶粒则逐渐缩小甚至消失。变形过程中晶格畸变逐渐向晶粒内部传递，使体系内原有的有序hcp结构受到影响而有序度降低。模拟结果分析发现，晶界迁移是纳米晶α-Zr在稳态蠕变过程中的主要变形机制，升高温度和增大应力水平会使晶界宽化，并促进组织演变。模拟不同能量粒子辐照后，体系中产生大量点缺陷，其扩散对蠕变有一定贡献，且这些缺陷最终汇集于晶界处，可提高晶界可动性。增大辐照能量可加大产生辐照缺陷的数量和尺寸，对蠕变过程起到更大的促进作用。

Zirconium alloys have been widely used because of their good mechanical properties, corrosion resistance, and suitable neutron absorption cross section. However, with the development of engineering technology, the requirements on the service performance, safety, and microstructure stability of zirconium structural materials are increasingly high. Creep refers to the phenomenon where the strain of the material increases with time under the action of stress lower than the yield strength, which will lead to the deformation of the structural material and eventually its failure. It is also an important problem faced by zirconium cladding materials in nuclear reactors. Nanocrystalline zirconium is a strengthening and toughening method, which may also improve other properties of nuclear materials. However, there are very few investigations on the microscopic creep mechanism in the atomic scale of nanocrystalline zirconium. Improving the creep resistance of zirconium materials plays an important role in the safety of components. Therefore, studying the creep behavior of nanocrystalline zirconium and its atomic mechanism is conducive to its better application in industries. In this study, the tensile creep behavior of nanocrystalline α-Zr under different conditions was investigated via molecular dynamics simulation. The main influencing factors of the creep process were analyzed and the influence of polycrystalline structure evolution and deformation mechanism during the steady-state creep process was studied. The effect of irradiation on the creep process was preliminarily explored. Results showed that temperature, stress, irradiation, and grain size affect the creep behavior of nanocrystalline α-Zr. Increasing the temperature and stress level and refining the grains can promote the creep process. The microstructure of the system changed significantly after the creep. Some grains grew up with the creep deformation process, while others gradually shrank, or even disappeared. During deformation, the lattice distortion gradually propagated from the grain boundary to the grains, partly reducing the degree of the hcp order. Simulation results showed that grain boundary migration is the main deformation mechanism of nanocrystalline α-Zr during steady-state creep. Increasing the temperature and stress level will thicken the grain boundary and promote the microstructure evolution. After the cascade collision due to neutrons of different energy levels, a large number of point defects were produced in the system and their diffusion contributed to the creep; these defects were finally collected at the grain boundary, improving the grain boundary mobility. Increasing the irradiation energy can increase the number and size of irradiation defects, promoting the creep process of the nanocrystalline system.