Mechanical properties that are considered to be deterministic in the macro-scale have been shown to be stochastic in the sub-micron length scale. The origin of such stochastic responses is not well understood. This work examines the potential influence of grain boundaries and grain orientations on the stochastic nature of pop-in and hardness measurement in annealed high purity polycrystalline Cu samples during low load nanoindentation. Statistical analysis on pop-in load and hardness showed that variations of these measurements depend on crystal orientations and is influenced by the indenter probe size. Analysis on the pop-in load statistics showed that pop-ins are likely initiate from an atomic sized precursor that leads to dislocation generation or expansion. Variation in hardness measurements near an arbitrary chosen grain boundary and the apparent grain boundary hardening effect observed may be related to the higher density of dislocations at and near the grain boundary.

在宏观尺度上被认为是确定性的机械性能已被证明在亚微米长度尺度上是随机的。这种随机响应的起源还没有被很好地理解。这项工作研究了晶界和晶向对低负荷纳米压痕过程中退火的高纯度多晶铜样品中突入和硬度测量的随机性的潜在影响。对弹入载荷和硬度的统计分析表明，这些测量值的变化取决于晶体的方向，并受压头探针尺寸的影响。对弹出载荷统计的分析表明，弹出可能是由原子尺寸的前驱物引发的，从而导致位错的产生或扩展。