La Yongxiao, Wen Chunyang, Feng Linna, Luo Yihui, Yun Di, Liu Wenbo
Department of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
Department of Materials, School of Natural Sciences, The University of Manchester, Sackville Street, Manchester M13 9PL, UK.
Nanomaterials (Basel). 2024 Sep 25;14(19):1548. doi: 10.3390/nano14191548.
During the γ phase-δ phase transition, U-50Zr fuel experiences spinodal decomposition, which has a significant effect on fuel properties. However, little is known about the spinodal decomposition of U-50Zr. The spinodal decomposition behavior in U-50Zr is studied in this research using the phase-field approach. The mechanism of spinodal decomposition from a thermodynamic perspective is studied, and the effects of temperature and grain boundary (GB) on spinodal decomposition are analyzed. It is found that the concentration of U atoms in the U-rich phase formed during spinodal decomposition is as high as 90%. The U-rich phase first appears at the GB position, and precipitation phases appear inside the grain later. Ostwald ripening occurs when larger precipitation phases on the GB absorb isolated smaller precipitation phases inside the grain. The coarsening rate of precipitation phases and the time it takes for spinodal decomposition to achieve equilibrium are both influenced by temperature.
在γ相-δ相转变过程中，U-50Zr燃料经历失稳分解，这对燃料性能有显著影响。然而，关于U-50Zr的失稳分解知之甚少。本研究采用相场方法研究U-50Zr中的失稳分解行为。从热力学角度研究了失稳分解的机制，并分析了温度和晶界对失稳分解的影响。研究发现，失稳分解过程中形成的富U相中U原子的浓度高达90%。富U相首先出现在晶界位置，随后在晶粒内部出现析出相。当晶界上较大的析出相吸收晶粒内部孤立的较小析出相时，会发生奥斯特瓦尔德熟化。析出相的粗化速率和失稳分解达到平衡所需的时间均受温度影响。
