利用相场模型对UO₂陶瓷粉末的烧结过程进行了模拟。在修正的相场模型中，不仅考虑了表面扩散、晶界扩散和晶格扩散3种各向异性的扩散机制对烧结组织形貌和烧结动力学的影响，而且考虑了不同陶瓷颗粒之间的界面能对烧结形貌的影响。基于实验条件和热力学物性参数，对UO₂陶瓷粉末在2000 K的烧结过程进行了模拟。模拟结果显示：初始形貌为圆形的陶瓷粉末有利于烧结过程的进行；烧结过程中存在大晶粒吞噬小晶粒的现象；晶界扩散机制是UO₂烧结过程中的主导机制；晶界能的改变导致晶界与相界之间的平衡二面角发生改变。在此基础上，模拟了多晶UO₂陶瓷粉末的烧结过程，模拟结果与实验结果吻合较好。

UO₂ is widely used as fuel in various nuclear reactors, and the sintering of UO₂ ceramic powder under high temperature is one of the most important processes during the preparation of UO₂ fuel. However, sintering is a very complicated process which is controlled by many simultaneous mechanisms. The phase field method was used to simulate the sintering process of UO₂ ceramic powder in the present work. In the modified phase field model, the influence of three anisotropic diffusion mechanisms, including surface diffusion, grain boundary diffusion and lattice diffusion, on the microstructure evolution during sintering was considered, and the effect of the interface energy between different ceramic particles on the sintering morphology was also considered. Based on the experimental conditions and thermodynamic parameters, the sintering process of UO₂ ceramic powder at 2000 K was simulated. The simulation results showed that the initial morphology of the ceramic powder affects the sintering kinetics; large grains grow more easily, and small grains disappear at the last stage of sintering; the GB diffusion mechanism is the dominant mechanism during the sintering; the equilibrium dihedral angle between GB and phase boundaries can be strongly affected by the GB energy. In addition, the sintering process of the polycrystalline UO₂ ceramic powder was also simulated, and the simulation results were in good agreement with the experimental results.