中文摘要：

Zr-4合金大晶粒样品在360℃和18．6MPa的O．01mol／LLiOH水溶液中经过70和160d腐蚀后，采用EBSD，SEM和HRTEM等方法，研究了氧化膜的显微组织和晶体结构，以及氧化膜的厚度与金属晶粒表面取向的关系．结果表明，样品经过160d腐蚀后，金属晶粒表面取向在靠近（0001）附近时氧化膜相对较厚，氧化膜的生长显示出明显的各向异性特征，但是在腐蚀70d后这种特征还不明显．从腐蚀70d后的样品中选取了表面取向接近（0001），（1010）和（1120）的金属晶粒，研究了它们表面上氧化膜／金属界面处的显微组织，不同取向金属晶粒表面上形成氧化膜的显微组织存在一定差别，在取向接近（0001）的晶粒表面生成的氧化膜中的m-ZrO2柱状晶晶粒之间的取向差比较大，氧化膜显微组织和晶体结构非常复杂，除主要的m-ZrO2外，还存在c-ZrO2，t-ZrO2以及亚氧化物Zr3O.氧化膜显微组织在腐蚀过程中不断发生演化，这会影响氧离子的扩散．进而影响氧化膜的生长，这种显微组织的演化过程还会受到氧化膜在不同取向晶粒表面上形成初期显微组织差别以及腐蚀时水化学条件的影响，这是Zr-4在LiOH水溶液中腐蚀时会出现氧化膜生长各向异性特征的主要原因．

英文摘要：

Zr-4 coarse-grained specimens were corroded in static autoclave at 360℃, 18.6 MPa in 0.01 mol/L LiOH aqueous solution for 70 and 160 d exposure. EBSD, SEM and HRTEM were used to investigate the micro- structures and crystal structures of oxide layers, and the relationships between the oxide thickness and the grain ori- entation of the metal matrix. The results showed that the oxide layers formed on the grain surfaces with the orienta- tions nearby basal plane （0001） were thicker, and exhibited a prominent anisotropic for the oxide growth when Zr-4 specimens were corroded in LiOH aqueous solution for 160 d, but this was not the case for 70 d. The grains with the surface orientation nearby （0001）, （10]-0） and （1120） were selected from the specimens corroded for 70 d to in- vestigate the effect of metal grain orientation on the microstructure of oxide layers. The results showed that the crystal structure and microstructure of oxide layers formed on different metal grains were obviously different, and the scattering of m-ZrO2 columnar grain orientations in the oxide layers formed on near basal plane （0001） was wider than that on near prismatic plane （1010） and （1120）. Besides the majority of m-ZrO2, c-ZrO2, t-ZrO2 and sub-oxide phase Zr30 were also detected at the oxide/metal interface, and it showed that the microstructure and crystal structure of oxide layers were very complex. The microstructural evolution of oxide layers will affect the diffusion of oxygen and subsequently the growth of oxide. Therefore, the microstructural evolution of oxide layers, which was affected by the different microstructure of oxide layers formed initially on grains and the water chemis- try of corrosion tests, resulted in the anisotropic growth of oxide layers when Zr-4 specimens were corroded in LiOH aqueous solution in subsequent corrosion tests.