Qualitative Study on Pile-up Effect on Hardness Test by Nano-Indentation

Hardness is a material parameter that enables it to resist plastic deformation, usually measured by the permanent depth of indentation. The hardness test can be carried out in macro (10^-3), micro (10^-6), and nano (10^-9) levels according to the specimen size. To obtain experimental macro - hardness numbers, there are several methods available such as Brinell, Vickers, and Rockwell hardness tests, etc. This study focuses on nanoindentation by numerical simulation, which leads to identifying the hardness properties of micro and nano-scale objects such as thin films and integrated circuits (IC), etc. The pile-up or sink-in effects can be observed in the nanoindentation test, which depends on the strain hardening coefficient of the target specimen. This pile-up or sink-in effect cannot be neglected in the nano-level as it obtains a considerable change of volume relative to the specimen dimension. There are no direct relationships between the pile-up or sink-in effects and mechanical properties. The objective of this study is to understand the behaviour of the pile-up effect on nanoindentation and obtain correlations between the pile-up effect and some material parameters using 2D and 3D numerical simulations.