A micro-mechanism based analysis for size-dependent indentation hardness

A micro-scale analytical model for predicting size-dependent microhardness is presented. The indentation size effect is explained by dissipation energy associated with the contact surfaces. Micro-mechanics mechanism of this energy dissipation is studied via a plastic deformation analysis of micro-scale asperities on the contact surface under indentation. The analysis shows that the microhardness depends not only on the properties of the bulk material under test, but also the properties of the contact surface, such as the plastic behavior of the micro-asperities on contact surfaces. The dependence of microhardness on the roughness parameters of the contact surfaces is also revealed from the analysis.