基于多尺度方法的纳米Cu薄膜摩擦过程中压头深度与速度效应研究

摘要

The surface scratch processes of nano-Cu film at different depths and velocities have been simulated by using bridging domain method.Firstly,both of the friction force and the system deformation energy increase obviously with the rise of indenter depth,while changing the friction velocity has little effect.Secondly,statistical analysis for the numbers of dislocation atoms shows that the indenter depth has a significant effect on the occurrence of dislocation in the friction process.The number of dislocation atoms increases significantly with the rise of indenter depth.The contributions of different deformation mechanisms to the total strain are quantitatively analyzed.The influences of indenter depth on the strain contribution are discrepant for different deformation mechanisms.The performance of FCC strain decreases with the rise of indenter depth and the contributions of dislocation and twinning atoms are less affected by the change of depth.Lastly,the friction velocity has almost no impact on micro-deformation mechanisms such as dislocation and twinning,which is consistent with the results of the friction force and the system deformation energy.%采用桥域方法(bridging domain method)对纳米尺度下Cu薄膜表面摩擦过程进行模拟,主要对不同压头压入深度和摩擦速度下的模拟结果进行对比分析.对摩擦阻力和系统变形能的对比分析表明,压深增大使得摩擦阻力和变形能显著增加,而摩擦速度增大对二者并无显著影响;对位错原子数目的统计分析表明,压深变化对摩擦过程中不全位错和全位错的发生具有明显影响,表现为不全位错和全位错原子数目随压深增加而显著增加;定量化分析位错、孪晶等不同变形机制对总应变的贡献比重表明,压深变化对摩擦过程中不同变形机制的应变贡献影响有差异,主要表现为FCC原子应变贡献随压深增加而降低,位错、孪晶原子应变贡献受压深变化影响较小.摩擦速度变化对摩擦过程中不全位错、全位错的发生以及不同变形机制的总应变贡献均无明显影响,这与不同摩擦速度下摩擦阻力、变形能的分析结果一致.