A series of simplified nanowires with specific convex and concave nanostructures was modelled and investigated via molecular dynamics simulations. The tensile speed was as low as 0.0758%/ps, allowing the nanowire system keeping in an equilibrium stretching state. The deformation behavior had been compared with the single crystal nanowire as well. The results demonstrate that the convex nanowire has the similar deforma-tion behavior as the single crystal nanowire does, showing a coincident evolution of the potential and stress-strain curves. Although the stress distribution along the z-axis exhibits a decrease around the convex nanostruc-ture,it cannot induce any initial dislocation and slip. On the contrary,the concave nanowire possesses plastic character rather than the elastic one. When the strain is less then 0.03, the potential energy of the concave nanowire increases slower than the convex and the single crystal nanowires do. However, this behavior be-comes the reverse when the strain is larger than this value. In addition,the first yield point comes earlier than the maximum stress for the concave nanowire. The stress distribution along the z-axis presents an increased stress around the concave nanostructure. Therefore, the first dislocations are generated near to the concave nanostructure. The analysis of the atomic arrangement further confirms this explanation.%构建了具有代表性的系列凸纳米线和凹纳米线,利用分子动力学模拟研究了2种微结构对拉伸形变的影响.结果表明,微凸纳米线与单晶纳米线表现出类似的行为,其能量和应力应变曲线等均无显著差异.改变不同的凸起高度未发现显著差别.沿z轴的应力分布分析表明凸微结构使局域应力降低,不能诱导产生初始位错滑移;微凹纳米线表现更明显的塑性形变特征,小应变时能量上升的幅度低于单晶和凸纳米线,但大应变条件下能量上升更高,微凹纳米线的第一屈服点早于单晶和凸纳米线,且其屈服应力不是最大应力,沿z轴的应力分布表明凹陷处产生增加的局域应力,凹陷附近可以诱导产生初始位错滑移.原子排布位图从微观上进一步阐述了上述形变特征.
展开▼
