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对取自同一块晶体的铜三晶（Ｔｃ）和双晶（ＢＣ）试样进行了恒塑性应变幅控制对称拉压疲劳实验，轴向塑性应变幅范围１．０×１０(－４)≤ ≤ ４×１０(－３)。结果表明，在低应变幅下，三晶及双晶试样的初始循环硬化曲线几乎重合。在较高应变幅下，三晶试样的硬化曲线高于双晶试样的硬化曲线且随着应变幅的增加差距增大。三晶体的循环应力应变（ＣＳＳ）曲线明显高于双晶的ＣＳＳ曲线。不论对ＴＣ还是ＢＣ试样，当 １＜１．５×１０(－３)时，轴向饱和应力随着的增加而缓慢上升，而当＞１．５×１０(－３)时，轴向饱和应力则随着Ｅｐｌ的增加快速上升。两曲线都无明显的平台区出现．表面形貌观察表明，在低应变幅下，三晶交点（ＴＪ）对各晶粒的主滑移有阻碍作用，在高应变幅下，在三晶交点附近，由于各晶粒的应变不相容性而产生的内应力导致了多滑移系统的启动．上述力学结果同表面形貌观察相一致。另外，在＞７．０×１０(－４)情况下，三晶交点处产生了微孔洞
Symmetric tension-compression fatigue tests were carried out on specimens of copper trilobal (Tc) and bicrystal (BC) taken from the same crystal. The axial plastic strain range was 1.0 × 10 (-4) ≤ ≤ 4 × 10 (-3). The results show that the initial cyclic hardening curves of three-crystal and twin-crystal samples almost coincide at low strain amplitude. At higher strain amplitude, the hardening curve of the three-crystal sample is higher than the hardening curve of the dual-crystal sample and the gap increases with the increase of the strain amplitude. The Cyclic Stress-Strain (CSS) curve of the three crystals is significantly higher than that of the twin crystals. For either TC or BC specimens, the axial saturation stress increases slowly with 1 <1.5 × 10 (-3), whereas for> 1.5 × 10 (-3), the axial Saturation stress increases rapidly with increasing Epl. No obvious two platform area appears. The observation of surface morphology shows that at low strain amplitude, the triple junction (TJ) has an inhibitory effect on the main slip of the grains. Under the high strain amplitude, near the intersection of three grains, The resulting internal stresses lead to the start-up of multi-slip systems. The mechanical results consistent with the observation of the surface morphology. In addition, in the case of> 7.0 × 10 (-4), micro-holes were formed at the intersections of the three crystals