UO2烧结过程的相场模拟  

Phase Field Simulations of the Sintering Process of UO

作　　者：孙正阳 杨超 柳文波[1,2] SUN Zhengyang;YANG Chao;LIU Wenbo(School of Nuclear Science and Technology,Xi'an Jiaotong University,Xi'an 710049,China;Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy,Xi'an Jiaotong University,Xi'an 710049,China;Advanced Research Institute of Multidisciplinary Science,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]西安交通大学核科学与技术学院,西安710049 [2]西安交通大学陕西省先进核能工程研究中心陕西省先进核能技术重点实验室,西安710049 [3]北京理工大学前沿交叉科学研究院,北京100081

出　　处：《金属学报》2020年第9期1295-1303,共9页Acta Metallurgica Sinica

基　　金：国家自然科学基金青年项目No.11705137;中国博士后科学基金项目Nos.2019M663738和2018T111053;清华大学新型陶瓷与精细工艺国家重点实验室项目No.KF201713;中国核工业集团有限公司领创科研项目。

摘　　要：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.

关 键 词：相场模型 UO2 烧结 扩散机制 

分 类 号：TG148[一般工业技术—材料科学与工程]