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从同一块纯铝双晶体截取试样，分别垂直或平行于其晶界面进行对称拉压疲劳实验．结果发现，在这两种加载方式下，晶界在晶体交变形变损伤断裂过程中的作用及机制有明显区别，横向晶界在变形过程中形成明显的不均匀形变带及多层次的影响区，比较容易萌生裂纹，而纵向晶界变形极小，只发现沿主滑移带的变形及微裂纹形核．相比之下，晶界结构（如∑值）对其自身损伤及裂纹萌生的作用则较弱．同时，对比试样实验结果还显示，相邻晶粒取向软硬相差较大的晶界，以及相对于应力轴的倾斜晶界，均能明显促进晶界疲劳裂纹的生长．
From the same piece of pure aluminum double crystal intercept the sample, respectively, perpendicular or parallel to its crystal interface symmetrical tension and compression fatigue test. The results show that under these two loading modes, the grain boundaries play a significant role in the process of crystal deformation and fracture, and the transverse grain boundaries form distinct inhomogeneous deformation bands and multi-level influence zones during deformation , Relatively easy initiation of cracks, and longitudinal grain boundary deformation is minimal, only found along the main slip band deformation and micro-crack nucleation. In contrast, the grain boundary structure (such as Σ value) on its own damage and crack initiation is weak. In the meantime, the experimental results of the comparative samples also show that the grain boundaries with large difference between the adjacent grain orientations and the oblique grain boundaries with respect to the stress axis can obviously promote the growth of the fatigue crack at grain boundaries.