分子動力学シミュレーションを用いたGuバイオクリスタルのナノインデンテーションに対する粒界効果

抄録

Nanoindentation is a typical technique for analysis of the mechanical responses of materials at nanometer scale. However, the effect of grain boundary during the nanoindentation process remains indistinct and need to be extensively researched because of their significant effects on the mechanical and physical properties. In this paper, molecular dynamics (MD) simulation was performed in order to investigate the grain boundary effect on nanoindentation of Cu biocrystal at different distances from grain boundary and different indentation speeds. The effect of grain boundary (GB) on indentation force, dislocation evolution, and hardness of Gu biocrystal was investigated. Firstly, as the indentation depth increases, the dislocation length and density increase. Secondly, indentation force drops phenomenon were detected from the obtained loading curves. These load drops are the result of the initiation of dislocation nucleation and so the transition from purely elastic to elastic-plastic deformation. When the dislocation reaches the GB, it will merge into the grain boundary plane until the indentation depth increase to some extent. The results also indicate that the maximum stress on the grain boundary is lower than its value far from the grain boundary. Finally, with the indentation speed increase, the stress, temperature and dislocation obtained from MD simulation became larger.