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利用扫描电镜电子通道衬度技术,对单滑移取向下,疲劳过程中Cu单晶从基体脉络位错结构到驻留滑移带(PSBs)位错结构的演化进行了观察.观察表明,PSBs的形成可以分为4个阶段,即脉络、通路、萌芽、真正形成完整的PSB位错结构.对以上4个阶段中典型位错结构的演化进行了模拟,并利用三维离散位错静力学方法给出了PSBs演化过程中典型位错结构内应力场的分布,相应地,利用有限元方法计算了外应力场的分布.结果表明:在从基体脉络位错结构到PS-Bs位错结构的演化过程中,内应力的分布是不均匀的.在通路和萌芽的尖端平均内应力没有太大的变化,而此处的平均外应力却比其他区域高,外应力提供了通路和萌芽长大的驱动力.在PSBs与基体边界处,内应力和外应力的值都急剧变化,因此存在切应变的不连续,积累到一定程度就会出现裂纹.
The evolution of dislocation structure of Cu single crystals from the matrix veins to the resident slip bands (PSBs) during the fatigue process was observed under scanning electron microscope (SEM) electron channel contrast technique. The observation shows that PSBs Can be divided into four stages, namely, the veins, the pathways and the sprouts, which form a complete PSB dislocation structure.The evolution of typical dislocation structures in the above four stages is simulated and the three-dimensional discrete dislocation statics The distribution of stress field in the typical dislocation structure during the evolution of PSBs is given. Correspondingly, the distribution of the external stress field is calculated by using the finite element method. The results show that in the dislocation structure from the basement veins to the PS-Bs During the evolution, the distribution of internal stresses is not uniform, and the average internal stress at the access and sprouting tip is not much changed, while the average external stress here is higher than in other regions. External stress provides access and germination and growth Of the driving force at the PSBs and the substrate boundary, the internal stress and external stress values are drastic changes, so there is shear strain discontinuity, the accumulation of cracks to some extent there will be.