高温高压水环境下锆合金力化学相互作用与失效机理研究

As the nuclear fuel cladding, zirconium alloy is one of the key materials in nuclear reactors. During the service process, the zirconium alloy needs to withstand the high-temperature and high-pressure water environments. Investigating the chemomechanical coupling behavior and failure mechanism of zirconium alloy is of great significance to improve the safety and economy of nuclear power plants. This project systematically studies the chemomechanical coupling problem in the polycrystalline oxide-substrate structure formed during the zirconium alloy oxidation process. The chemomechanical coupling theory for the oxidation process of zirconium alloys will be first developed. The diffusion mechanism in the polycrystalline oxide-substrate structure and the factors influencing the diffusion will be analyzed. The oxidation kinetics with the chemomechanical coupling effect will be figured out. The stress distribution along the thickness direction and lateral direction in the polycrystalline oxide-substrate structure and the stress concentration near the grain boundary will be investigated. Then, the crack propagation criterion with the chemomechanical coupling effect will be established. The relationship between zirconia phase transformation and stress will be accurately characterized. Moreover, the failure mechanism of the zirconium oxide layer will be revealed and the mechanism of improving the oxidation resistance of the zirconium alloy will be explored, which can provide theoretical support for predicting the lifespan of the zirconium alloy.

锆合金作为核燃料元件包壳，是核反应堆的关键核心材料之一。在服役过程中，锆合金需要经受高温高压水环境，研究其力化学相互作用与失效机理对提高核电站的安全性和经济性具有重大意义。本项目针对锆合金氧化过程形成的多晶氧化层-基体结构的力化学耦合问题进行系统研究，发展适用锆合金氧化过程的力化学耦合理论，分析反应物在多晶氧化层-基体结构中的扩散机制以及影响因素，给出力化学耦合效应下的氧化动力学，研究多晶氧化层-基体结构中应力沿氧化层厚度方向与横向方向的分布以及晶界附近的应力集中现象，建立力化学耦合作用下的裂纹扩展准则，准确表征氧化锆相变与应力的定量关系，揭示锆合金氧化层的失效机理，探究提高锆合金抗氧化性能的方法，为预测锆合金的使用寿命提供理论支持。

锆合金作为核燃料元件包壳，在服役过程中需要经受高温高压水环境，研究其力化学相互作用与失效机理对提高核电站的安全性和经济性具有重大意义。本项目发展了适用于锆合金氧化的力化学耦合理论，表征了氧化锆应力和相变的定量关系。建立了弹塑性力化学耦合模型、粘塑性力化学耦合模型以及考虑相变影响的力化学理论模型，并数值分析了氧化过程中的力化学耦合规律。建立了多晶氧化层-基体理论模型。本研究可为提高锆合金抗氧化性能提供思路，并为锆合金寿命预测提供理论支持。