To explore the dependence of mechanical behavior on the crystal size, the \( [\bar{1}11] \)-oriented Cu single crystal was selected as a target material, and the variations of tensile and tension–tension fatigue behavior with the crystal specimen thickness (t) were systematically investigated. The results show that, with the decrease of t, the tensile yield strength continuously increases, especially as t < 0.4 mm, which is related to an enhanced role of surfaces in affecting dislocation activity; ultimate tensile strength first increases and elongation has almost no change as t is decreased from 2.0 to 1.0 mm, but with continuously decreasing t, both of them decrease; as t = 0.1 mm, the slight increases in ultimate tensile strength and elongation occur. With the decrease of t, the corresponding dislocation structures are evolved from the cell walls into the cells and tangles; meanwhile, the density of slip bands (SBs) decreases. Moreover, the obvious concentrated SB regions and notable cross-slip traces are clearly observed in thicker crystals. The fatigue life has no notable change as t = 2.0 and 1.0 mm, but increases subsequently with decreasing t due to the decrease in the plastic strain accumulation together with an enhanced interaction between the dislocations in the surface zone.

为了探索机械行为对晶体尺寸的依赖性，选择了取向为\（[\ bar {1} 11] \）的Cu单晶作为目标材料，并研究了拉伸和拉伸-拉伸疲劳行为随晶体尺寸的变化。系统地研究了晶体试样的厚度（t）。结果表明，随着t的减小，抗拉屈服强度不断增加，尤其是当t  <0.4mm时，这与表面在影响位错活性方面的作用增强有关。极限抗拉强度先增加，而伸长率几乎没有变化，t从2.0减小到1.0 mm，但是随着t的不断减小，两者都减小。如t  = 0.1 mm，极限抗拉强度和伸长率会略有增加。随着t的减小，相应的位错结构从细胞壁演化为细胞和缠结。同时，滑带的密度降低。此外，在较厚的晶体中清楚地观察到明显的SB集中区域和明显的交叉滑动痕迹。当t  = 2.0和1.0 mm时，疲劳寿命没有显着变化，但随着塑性应变累积的减少以及表面区域中位错之间相互作用的增强，随t的增加而增加。