纳米硬度实验中的多位错生成分析

Analysis of Multi-Dislocation Nucleation in Nanoindentation

本文利用边界单元法及基于PeierlsNabarro模型的位错理论,分析了理想纳米触头下多位错的生成,得到了滑移面上多位错的构形以及表面位移与载荷的关系曲线。根据得到的计算结果分析了薄膜厚度的影响,得到了与已有实验结果相同的结论。通过把表面看成一个包含在无穷大弹性体中的无穷大弹性体中无穷大裂纹来考虑表面的影响,从而可以直接采用已有的边界积分方程。该方法在连续介质力学的计算中引入了包含原子信息的层间势能函数,为分析多尺度的力学问题提供了有效的方法。

Multi dislocation nucleation under an idealized nanoindenter was analyzed based on the Peierls Nabarro dislocation model. The boundary element method was employed to obtain the multi dislocation profiles that correspond to the discontinuous displacement between the adjacent atomic layers along the slip planes. The relationship of the load on the indenter and the surface displacement was also obtained. The effects of the film thickness on the nanoindentation were discussed based on the numerical results, and it is consistent with the experimental observation. By treating the surface as part of an infinite crack embedded in the infinite medium, a rather straightforward approach was adopted to account for the surface effect. This proposed method introduces atomic scale features into the simulation of a continuum approach, which provides a powerful tool to analyze the multi scale structure.