Atomic scale stick-slip caused by dislocation nucleation and propagation during scratching of a Cu substrate with a nanoindenter: a molecular dynamics simulation
Atomic scale stick-slip caused by dislocation nucleation and propagation during scratching of a Cu substrate with a nanoindenter: a molecular dynamics simulation
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DOI：
10.1016/j.wear.2005.01.002
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发表时间：
2005-07
期刊：
影响因子：
5
通讯作者：
M. Cho;S. Kim;D. Lim;H. Jang
中科院分区：
文献类型：
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作者：
M. Cho;S. Kim;D. Lim;H. Jang
采用嵌入原子势的分子动力学模拟方法研究了纳米压头对铜表面的刮擦作用。模拟采用刚性Ni尖端（半径为2.5nm）在Cu{001}表面上进行刮擦。在不同的压痕深度（0 ~ 0.36nm）、速度（4.2 ~ 49.8m/s）和温度（4 ~ 300k）下，通过尖端刚体平移模拟了含有20万个原子的Cu衬底和不同的划痕条件。在划痕模拟过程中观察到原子尺度的粘滑现象，这种现象与位错的形核和扩展有关。粘滑过程伴随着弹性变形过程中摩擦力的缓慢增大，随后由于塑性屈服导致摩擦力的突然减小。粘滑现象以大致相同的时间重复发生，并且在一定范围的滑动条件下，在刮擦深度、速度和温度方面都很明显。模拟结果还表明，由肖克利部分位错组成的v形位错在自由表面附近沿晶体滑移系统传播。摩擦振荡的详细分析表明，在刮擦过程中位错的形核比部分位错随后的扩展在粘滑过程中的突然下降起更重要的作用。
Scratching of a Cu surface using a nanoindenter was studied by molecular dynamics simulation using embedded atom potentials. The simulation was carried out using a rigid Ni tip (radius=2.5nm) scratching on a Cu{001} surface. The Cu substrate contained 200,000 atoms and various scratching conditions were simulated by the rigid body translation of the tip at different indentation depths (0–0.36nm), speeds (4.2–49.8m/s), and temperatures (4–300K). Atomic scale stick-slip was observed during the scratching simulation and it was associated with dislocation nucleation and propagation. The stick-slip accompanies the slow increase of friction force during the elastic deformation and is followed by an abrupt decrease of the friction force due to plastic yielding. The stick-slip was repeated with an approximately same period and it was pronounced at certain ranges of sliding conditions in terms of scratching depth, speed, and temperature. The simulation also exhibited that the V-shaped dislocations consisting of Shockley partial dislocations were constructed and they propagated near the free surface along the slip system of an fcc crystal. Detailed analysis of friction oscillation suggested that the nucleation of the dislocation during scratching plays more important roles in determining the abrupt drop during stick-slip than subsequent propagation of partial dislocations.