Tie Importance of Contact Radius for Substrate-Independent Property Measurement of Thin Films

Abstract

In indentation literature, there is support for the proposition that the extents of the elastic and plastic fields scale with the contact radius. For example, in Hertzian contact, the locations of constant-shear-stress lines scale with the contact radius. This idea has significant consequences with respect to measuring substrate-independent properties of thin films. If it is the contact radius that determines the extent of the elastic and plastic fields, then any general rule expressed in terms of the indentation depth is only appropriate for one indenter geometry - the one for which it was determined. In this work, three different indenter geometries were used to measure the hardness of one thin film. For all geometries, hardness results are expressed in terms of both depth and contact radius