基于多晶材料的微观拓扑结构,从多晶Cu纳米压痕中晶粒内部、晶界面、三叉晶界和顶点团等4类微观结构与缺陷结构的配位数、内应力、原子势能等方面,研究了压痕表面位错缺陷的演化机制。结果表明：当高维数的微观结构承载压应力时,与其邻近的低维数微观结构表现为拉应力,且更低维数的微观结构(顶点团)更易表现为拉应力;位错缺陷形核时其原子具有较高的内应力与原子势能,扩展时其边缘的不完全位错原子内应力高于内部堆垛层错原子内应力;位错形核与扩展和内应力的累积与释放具有相似的方向性,首先扩展至低维数的顶点团、三叉晶界,而后传递至高维数的晶界面并止于晶界面。

In the present technology, the manufacture of micro-electro-mechanical system (MEMS) and nano-electro-mechanical system (NEMS) are limited by the lack of mechanism of material processing, especially the mechanism of the polycrystalline materials. In this work, based on the microstructures of polycrystalline copper, the evolution mechanism of dislocations on the polycrystalline copper nanoindentation surface is researched by the four types of microstructures in polycrystalline materials, including grain cell, grain boundary, triple junction and vertex points. In addition, the coordination number, internal stress and atomic potential energy of the dislocations defects are also considered. The results show that when the microstructures with high dimension number carry the compressive stress, the adjacent microstructures with low dimension number appear tensile stress and the microstructures with lower dimension number like vertex points is more likely to appear tensile stress. The dislocation atoms accumulate high internal stress and atomic potential energy during the dislocation nucleation. The internal stress of the imperfect dislocation atoms at the dislocation edge is higher than that of the stacking layer atoms inside the dislocations during the dislocation growth. The process of nucleation and growth, and the internal stress accumulation and release both have similar directionality. They both firstly extended to the microstructures with lower dimension number like vertex points and triple junction, and then expend to and stop at the grain boundary with high dimension number.