渗氢后再结晶状态Zr-4合金拉伸变形的原位观察

利用扫描电镜原位观察和相应的多相有限元数值分析方法，研究了渗氢后再结晶状态Zr-4合金拉伸过程中氢化物的变形行为以及其对基体变形行为的影响。结果表明，氢化物自身具有一定的塑性变形能力，在具有良好塑性的基体约束下，可以与基体一起发生较大的变形，但是氢化物的变形能力和其在Zr-4合金中的分布和形貌密切相关：稀疏分布的氢化物，易发生变形，不易出现裂纹；单个片状的氢化物可以被基体中的滑移线穿过；而在大块氢化物团聚体内部易出现裂纹。氢化物的形貌不仅影响基体的变形行为；而且对基体的断裂也有显著的影响。渗氢后Zr-4合金的断裂属于韧性断裂，断裂时材料内部出现多裂纹源，无主裂纹出现。

IN SITU OBSERVATION OF TENSILE DEFORMATION IN THE RECRYSTALLIZED ZIRCALOY-4 AFTER HYDRIDIZATION

The SEM in situ observation and corresponding multiphase finite element analysis were performed to investigate the tensile deformation behavior of hydride and its effect on the matrix deformation of recrystallized zircaloy-4 after hydridization. The results show that hydrides can deform plastically together with the zircaloy-4 matrix, which depends on the morphologies of hydrides distributed in zircaloy-4 matrix. Easy deformation and no cracking occur for sparsely distributed hydrides while slip-line can go through the isolated hydrides. However, microcracks have been produced inside the massive hydride aggregation. Both deformation and fracture behaviors of the zircaloy-4 matrix are influenced by the morphologies of hydride. The fracture of hydrided zircaloy-4 displays ductile, while there are a number of crack origins and no main cracks.