Results of an investigation of the nature of load-displacement curves, pop-in events and indentation size effect of the (001) and (100) faces of KDP crystals by nanoindentation deformation under Berkovich indenter at different loads are presented and discussed. It was found that: (1) load-displacement curves reveal numerous pop-in events but these pop-in events occur less frequently on the (100) face than on the (001) face, (2) different segments of individual load-displacement curves are explained by plastic deformation under the indenter, (3) the value of indentation displacement excursion d of pop-in events lies between 3 and 20 nm, (4) nanohardness H lies between 2.2 and 3.3 GPa and between 1.6 and 3.2 GPa for the (001) and (100) faces, respectively, and is comparable with that reported before, whereas penetration independent hardness H₀ obtained from analysis of the H(h) data is 2.04 and 1.41 GPa for the (001) and (100) faces, respectively.

提出并讨论了通过在不同载荷下在Berkovich压头下纳米压痕变形对KDP晶体的（001）和（100）面的载荷-位移曲线，弹出事件和压痕尺寸效应进行研究的结果。发现：（1）载荷-位移曲线揭示了许多弹入事件，但这些弹入事件在（100）面上的发生频率低于在（001）面上，（2）各个载荷的不同段-位移曲线通过压头下的塑性变形来解释，（3）弹出事件的压痕位移偏移值d在3至20 nm之间，（4）纳米硬度H（001）和（100）面分别在2.2至3.3 GPa和1.6至3.2 GPa之间，与之前报道的相当，而通过分析H（h）数据获得的与渗透无关的硬度H ₀为（001）和（100）面分别为2.04和1.41 GPa。