Department of Physics, McGill University, Montreal, QC H3A2T8, Canada.
Nanotechnology. 2014 Jan 17;25(2):025701. doi: 10.1088/0957-4484/25/2/025701. Epub 2013 Dec 12.
We have carried out nanoindentation studies of gold in which the indenter is atomically characterized by field-ion microscopy and the scale of deformation is sufficiently small to be directly compared with atomistic simulations. We find that many features of the experiment are correctly reproduced by molecular dynamics simulations, in some cases only when an atomically rough indenter rather than a smooth repulsive-potential indenter is used. Heterogeneous nucleation of dislocations is found to take place at surface defect sites. Using input from atomistic simulations, a model of indentation based on stochastic transitions between continuum elastic-plastic states is developed, which accurately predicts the size distributions of plastic 'pop-in' events and their dependence on tip geometry.
我们进行了金的纳米压痕研究，其中压痕通过场离子显微镜进行原子级表征，且变形尺度足够小，可以直接与原子模拟进行比较。我们发现，分子动力学模拟正确地再现了实验的许多特征，在某些情况下，只有使用原子粗糙的压痕而不是光滑的排斥势能压痕时才如此。位错的不均匀形核发生在表面缺陷处。利用原子模拟的输入，开发了一种基于连续弹塑性状态之间随机跃迁的压痕模型，该模型准确地预测了塑性“弹出”事件的大小分布及其对尖端几何形状的依赖性。
