Abstract

This study concerns the effect of bicrystal spatial orientation on the iron Σ5 boundary under nanoindentation tests. The orientation of the bicrystal is changed relative to the indenter by the parameter “nanoindentation angle” to create dislocation collisions with grain boundary in different directions and to determine the possibility of transmission of these dislocations through the grain boundary. Simulations were carried out for nanoindentation angles between −90° and 90° with a resolution of 18°. Molecular dynamics with EAM atomic potential functions are employed for the simulations. The effect of nanoindentation angle on the crystals Young’s modulus, shear stress, hardness, and Poisson’s ratio were determined. Due to the periodicity which has been observed in all of the aforementioned quantities of the rotated crystal, analytical equations were extracted by adapting the Fourier series expansion on the calculated data. Some explanations were provided for the dislocation behaviors based on the physics of the problem and also by the results reported in the literature. Simultaneous effects of Poisson’s ratio and pile-ups on each other were also investigated and interpreted.

摘要

本研究涉及纳米压痕试验下双晶空间取向对铁 Σ5 边界的影响。通过参数“纳米压痕角”相对于压头改变双晶的取向，以在不同方向上与晶界产生位错碰撞，并确定这些位错通过晶界传输的可能性。对 -90° 和 90° 之间的纳米压痕角度进行了模拟，分辨率为 18°。模拟采用具有 EAM 原子势函数的分子动力学。确定了纳米压痕角度对晶体杨氏模量、剪切应力、硬度和泊松比的影响。由于在所有上述旋转晶体数量中观察到的周期性，通过对计算数据进行傅里叶级数展开来提取分析方程。基于问题的物理学以及文献中报道的结果，对位错行为提供了一些解释。泊松比和堆积对彼此的同时影响也进行了调查和解释。