纳米线涂层中失配位错偶极子分析

研究了纳米线环形晶体薄膜涂层中失配位错偶极子与纳米线的干涉效应,并考虑纳米尺度应力效应及纳米线晶格失配的影响.运用弹性复势方法,分别获得了涂层和纳米线区域复势函数的精确解析解.利用求得的应力场和Peach-Koehler公式,得到了作用在螺型位错偶极子上像力和失配应力的精确表达式.算例结果表明,涂层纳米线界面应力和失配应力对涂层中失配位错偶极子的作用影响很大,由于界面应力和失配应力的存在,可以改变涂层内位错偶极子与纳米线干涉的引斥规律.与宏观尺度下的线型材料相比,纳米线材料由于界面效应的影响,位错偶极子在涂层中平衡位置的数量增加,涂层中更容易产生失配位错偶极子.考虑纳米线晶格失配的影响后,位错偶极子在涂层中平衡位置的数量增加.由此可知,减小纳米线晶格失配的影响,可以控制失配位错偶极子的产生.

ELASTIC ANALYSIS OF MISFIT DISLOCATION DIPOLES IN AN ANNULAR COATING LAYER ON A CYLINDRICAL NANOWIRE

The interaction between misfit dislocation dipoles in the nanoscale coating layer and the nanowire is investigated. The analytical solutions of complex potential functions in the coating layer and the nanowire are derived by means of the complex variable method. With the aid of the Peach-Koehler formula, the explicit expression of the image force and the mismatch stress acting on the screw dislocation dipoles are given. The results show that the impact of the interface stress and the mismatch stress on the motion of misfit dislocation dipoles is very significant. Under certain conditions, the presence of the interface stress and mismatch stress can change the interaction mechanism between the misfit dislocation dipoles and nanowire. Compared to the macroscale linear materials, the equilibrium position of misfit dislocation dipoles in the nanoscale coating layer will increase for considering the interface effect, the coating layer is more easy to generate misfit dislocation dipoles. The equilibrium postion of misfit dislocation dipoles in the nanoscale coating layer will increase for considering the effect of nanowire lattice mismatch. It can be seen, we can control the generation of misfit dislocation dipoles by reducing the effect of nanowire lattice mismatch.