晶间腐蚀抗力不足是制约7000系列超高强铝合金广泛用于航空航天等国家重大装备制造的关键问题。具有密排面与密排面匹配特征的{111}/{111}近奇异晶界是一类较比一般晶界更耐蚀的特殊晶界，提高此类晶界的比例，有望显著提高超高强铝合金的晶间腐蚀抗力。为排除析出相及成分起伏等因素的干扰，从本征上了解铝及其合金生成{111}/{111}近奇异晶界的基本规律，本研究选用99.99%高纯铝作为实验材料，采用基于电子背散射衍射和晶界界面匹配表征方法深入研究了该材料经室温和200℃叠轧(真应变ε = 4.6)及370℃再结晶退火后的{111}/{111}近奇异晶界分布及其形成机理。结果表明，经200℃叠轧及再结晶的样品，其{111}/{111}近奇异晶界的比例达到16.71%，较室温叠轧后再结晶的样品提高约68%。电子背散射衍射原位再结晶退火实验显示，经200℃叠轧的样品主要通过连续再结晶机制完成再结晶，再结晶前后织构类型基本保持不变；轧制态样品中，回复良好的Taylor取向和Goss取向的亚晶构成材料的主体部分，在后续退火过程中，这两类亚晶各自通过其关联界面持续吸收位错实现对邻近亚晶的转动与合并，并以此完成连续再结晶；Taylor取向和Goss取向之间存在<1 1 1>/θ或近<1 1 1>/θ取向差关系，这两种取向的晶粒相遇后可通过其界面的局部调整和再取向形成{111}/{111}近奇异晶界。高分辨透射电子显微镜观察表明，此类{111}/{111}近奇异晶界处存在等间隔分布的刃位错阵列，用以协调偏离精确匹配位置的错配，其界面能量约为251 mJ/m²，显著低于一般晶界的500 mJ/m²。

Insufficient intergranular corrosion (IGC) resistance limits the use of 7xxx-series ultra-high-strength aluminum alloys in aerospace and other critical structural applications. {111}/{111} near-singular boundaries (NSB) are special boundaries featured in a inter-connection of two {111} closest planes. They show higher corrosion resistance than the random grain boundaries. A higher fraction of these boundaries can markedly improve IGC resistance in ultra-high-strength aluminum alloys. In order to understand how {111}/{111} NSB form in aluminum alloys, 99.99% (mass fraction) high-purity aluminum were used as the experimental material. This choice can avoid the interference from precipitates and compositional fluctuations. {111}/{111} NSB were examined by EBSD measurement and the grain boundary inter-connection characterization method. The samples were processed by accumulative roll bonding (ARB) either at room temperature or at 200 ℃ (true strain ε = 4.6) followed by recrystallization annealing at 370 ℃. The results indicated that the sample ARB-ed at 200 ℃ and recrystallized had a higher {111}/{111} NSB fraction compared to the sample ARB-ed at room-temperature and recrystallized. Specifically, the {111}/{111} NSB fraction in the former was 16.71%, about 68% higher than that in the latter. In situ EBSD annealing experiments, at the temperatures ranging from ambient to 370 ℃, show that the sample ARB-ed at 200 ℃ undergoes mainly continuous recrystallization. The texture of recrystallization keeps almost the same as that observed in the ARB-ed state. After ARB-ed at 200 ℃, well-recovered Taylor- and Goss-oriented sub-grains constitute the main part of the sample. During annealing, these sub-grains continuously absorb dislocations by the associated interfaces, driving sub-grains rotation and coalescence and promoting continuous recrystallization. Taylor and Goss orientations show a <111>/θ (or near-<111>/θ) misorientation. When grains of these orientations impinge, local interfacial adjustment and re-orientation give rise to the formation of {111}/{111} NSB. High-resolution transmission electron microscopy reveals periodically spaced arrays of edge dislocations at these {111}/{111} NSB. These dislocations accommodate the mismatch caused by the deviations from the exact {111}/{111} inter-connection. The grain boundary energy of such {111}/{111} NSB is about 251 mJ/m², substantially lower than that of random grain boundaries (about 500 mJ/m²).