U-Nb合金氢化物生长动力学的应变能研究

Study on Strain Energy on the Hydride Growth Kinetics of U-Nb Alloys

为研究不同铀铌合金（U，U-25％Nb，U-57％Nb（质量分数））的氢化表现行为以及合金元素铌在氢化过程的作用规律和机制，以应变能理论为基础，对3种合金表面氢化物生长进行模拟研究，获得了氢化物生长过程中的应力、应变和应变能演变，发现3种材料在氢化物生长过程的应变能存在明显差异．3种材料表面形成铀氢化物需克服的应变能顺序为：U-5．7％Nb〉U〉U-2．5％Nb．结合化学反应活化能理论，获得3种材料的氢腐蚀倾向性顺序为：U-2．5％Nb〉U〉U-5．7％Nb．应变能模拟结果与3种材料氢化腐蚀动力学实验一致。说明了氢化物生长的应变能模型的正确性，证实了氢化物形成时由于体积变化大，导致了巨大应变能形成，直接影响了铀氢化物的形成动力学．

To investigate the difference of the hydride growth kinetics of U, U-2.5%Nb, and U-5.7%Nb （mass fraction） based on strain energy theory, the deformation, stress, and strain energy during hydride growth were investigated by the finite element model （FEM） according to the mechanical properties of the three U materials. The results showed that the strain energy because of hydride expansile growth in the matrix is considerably different for the three U materials. When hydride grows, the order of the strain energy value is U-5.7%Nb〉U〉 U-2.5%Nb. This indicates that based on reaction activation energy theory the U-2.5%Nb alloy is the most susceptible to hydrogen corrosion, followed by U, while U-5.7%Nb is the most resistant to hydrogen corrosion. The calculated results of the strain energy agree with the hydride growth kinetics experimental results, which also show that the hydride growth model is correct. This study shows that the large strain energy because volume change during hydride growth plays an important role in the growth kinetics.