{111}/{111}近奇异晶界较比一般晶界更耐蚀，如何提高此类晶界比例以显著提高Al及其合金晶界腐蚀抗力是一个新课题。本工作选用99.99% (质量分数)高纯Al为研究对象，考察晶粒长大对{111}/{111}近奇异晶界的影响。样品经室温多向锻造和370℃再结晶退火后，再经500℃保温不同时间，采用基于EBSD和五参数分析的晶界界面匹配表征方法对样品进行测试和分析。结果表明，随着晶粒长大，{111}/{111}近奇异晶界的比例显著增加。当平均晶粒尺寸由38 μm长大至77 μm时，{111}/{111}近奇异晶界的比例由3.91%增加至6.56%。离线原位EBSD和晶界迹线分析表明，晶粒长大过程中，{111}/{111}近奇异晶界主要通过具有<111>/θ(θ为取向差转角)取向差关系的两两晶粒吞并周边晶粒并相遇后形成；具有<111>/θ取向差关系的相邻晶粒，其晶界通过再取向调整至{111}/{111}位置，亦可形成此类近奇异晶界。{111}/{111}近奇异晶界存在旋错结构，其原子排列有序度显著高于一般晶界，这是此类晶界比一般晶界更耐蚀的原因。

The {111}/{111} near singular boundary is more resistant to intergranular corrosion than random boundary. At present, enhancing the fraction of such boundary to improve the performance against intergranular corrosion has been the latest issue in microstructure design and control for aluminum and its alloys. In the current work, high-purity aluminum was selected as an experimental material, and the effects of grain growth on {111}/{111} near singular boundary were investigated. First, the sample was given multi-directional forging at room temperature followed by recrystallization annealing at 370^oC. The recrystallized samples were heated at 500^oC for varied time to promote grain growth and to obtain microstructures with various grain sizes. Then, the {111}/{111} near singular boundary in the samples was measured by grain boundary inter-connection characterization, which was established on the basis of EBSD and five-parameter analysis. Results show that the length fraction of {111}/{111} near singular boundary increases with the increase of grain size. For example, the fraction of {111}/{111} near singular boundaries is 3.91% when the averaged grain size is 38 μm, whereas it increases to 6.56% as the averaged grain size reaches 77 μm. Off-line in situ EBSD coupled with grain boundary trace analysis indicates that the {111}/{111} near singular boundary is primarily formed via the encounter of two growing grains with <111>/θ misorientation relationships (θ is the rotation angle). Meanwhile, the {111}/{111} near singular boundary is also formed via the re-orientation of grain boundaries with <111>/θ misorientation. HRTEM observation reveals that the {111}/{111} near singular boundary has disclination, and the degree of atomic ordering of such a boundary is higher than that of random boundaries. Therefore, such a boundary is more resistant to intergranular corrosion compared with random boundary.