原子尺度的纳米压痕模拟技术

Atomic Scale Simulations of Nanoindentation

通过纳米压痕的分子动力学模拟研究并解决了模拟中的诸多问题.一是加载方法及对系统中压头载荷的定义,定义了刚性的压头,并以与压头相接触的截断半径以内的原子所受的力为压头的载荷,结果表明,文中所定义的方法及所得出的载荷-位移曲线较好地反映了材料的特性,为分析和比较材料的特性及在加(卸)载过程中位错的产生和运动提供了依据.二是在原子尺度材料表现出一定程度的滞弹性,会影响到对材料硬度和弹性模量的测定,解决的方法是在卸载前让系统充分地松弛.由于滞弹性的影响,模拟结果是与加载速度相关的.

This paper solved some problems about the simulations of nanoindentation by means of molecular dynamic simulations. One of the problems is the loading method and the definition of the tip load. This paper defined a rigid tip, the load of the tip is calculated by the forces of atoms within the radius-cut. The results show that above method and the P-h curve reflect the material's properties very well, and can be used to analyze the material's properties and the nucleation and movement of dislocations. Another problems is that the material in atomic scale has viscoelasticity, which will effect the measurement of hardness and elastic modulus. The solving method is to drift thoroughly before unloading. This paper also toughs upon the effects to the viscoelasticity by loading speed.