采用电子背散射衍射(EBSD)技术研究了晶粒尺寸不同的纯Cu试样经冷轧变形和高温退火后的晶界特征分布(GBCD). 结果表明, 细晶(约12 μm)试样经小变形冷轧后在高温短时退火过程中形成了比例高达75.7%的Σ3ⁿ (n=1, 2, 3)特殊晶界,  而且具有Σ3ⁿ  (n=1, 2, 3)取向关系的特殊晶粒团的平均尺寸较大, 达到200 $\mu$m, 试样的GBCD得到较好优化; 随着原始晶粒尺寸的增大, 试样经冷轧退火后, 其特殊晶界比例和特殊晶粒团尺寸均显著减小. EBSD原位观察、孪晶过滤(twin filtering)和五参数法(FPM)分析表明, 三叉晶界(triple junctions)是轧制退火过程中非共格Σ3晶界的有利形核位置, 非共格Σ3晶界的迁移反应可促进GBCD的优化, 这是细晶试样经轧制退火后, 其GBCD得到较好优化的关键原因.

Pure copper (99.97%) samples with varied grain sizes were cold rolled and annealed at first and then their grain boundary character distributions (GBCDs) were characterized by electron back scatter diffraction (EBSD) techniques. The results showed that the sample with finer initial grain size (12 μm) appeared to be largely populated by the so-called special boundaries such as Σ3ⁿ (n=1, 2, 3) after cold rolling and annealing, the fraction of Σ3ⁿ boundaries reached 75.7% and the averaged size of clusters of grains with Σ3ⁿ (n=1, 2, 3) orientation relationships (Σ3ⁿ CG) were as large as 200 $\mu$m in this sample. However, with initial grain size increasing, the fraction of special grain boundaries as well as the size of Σ3ⁿ CG in the samples were decreasing dramatically. In situ EBSD observation, twin-filtering and five parameter method (FPM) analyses indicated that triple-junctions are the preferred sites for the nucleation of incoherent Σ3 boundaries which play a important role in enhancing the fraction of special boundaries.It accounts for primarily the desired GBCD results as obtained in the sample with finer initial grain size.