中空铜纳米线的拉伸断裂分布与初始滑移分布的关系

Relationship between the tensile fracture distribution of the hollow copper nanowires and the initial slip distribution

构建了系列球形中空结构的纳米线(NW),采用分子动力学(MD)对每个模型300个不同初始态的样本开展拉伸形变模拟。并利用基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)机器学习算法,获得了初始滑移面的位置。基于大数据统计,分析了初始滑移位置分布以及断裂位置分布两者之间的相关性。研究结果表明:当内部中空半径较小时,断裂位置分布形成于塑性形变阶段,初始滑移分布与断裂位置分布之间无显著的相关性;但是对于脆性特征明显的大中空半径的NW,高能内表面诱导产生的滑移面迅速积累,产生颈缩并导致最终的断裂。因此当内部中空结构达到一定尺寸时初始滑移位置的分布与最终断裂位置的分布之间有明确的因果关系。

To investigate the relationship between the fracture failure and the initial microstructure of the hollow nanowires(NW),a series of spherical hollow structures were constructed and molecular dynamics(MD)simulations were performed with 300 samples that have different initial states.The position of the initial slip plane was obtained using the density-based spatial clustering of applications with noise(DBSCAN)machine learning algorithm.Based on big data analysis,the distribution of the initial slip position and the fracture position were analyzed.The result of the correlation between the two shows that when the inner hollow radius is small,the distribution of fracture positions is formed during the plastic deformation stage,so there is no correlation between the distribution of initial slip and fracture positions.However,for brittle NW with significantly larger hollow radii,the slip plane induced by the high-energy inner surface quickly accumulates,resulting in necking and ultimately fracture.Therefore,when the internal hollow structure reaches a certain size,there is a clear causal relationship between the distribution of initial slip positions and the distribution of final fracture positions.