Title: Piling-up effects on nanoindentation impressions of metals and coatings investigated by atomic force microscopy : influence on hardness measurements
Abstract:Atomic force microscopy (AFM) allows detecting structures of nanometric scale around indentation impressions such as elastic recovery, elastic-plastic deformations, cracks, piling-up and sinking-in ef...Atomic force microscopy (AFM) allows detecting structures of nanometric scale around indentation impressions such as elastic recovery, elastic-plastic deformations, cracks, piling-up and sinking-in effects. Such behaviours occurring in the nanoindentation test affect the determination of hardness and Young's modulus which depend strongly on the estimate of area of contact between the indenter and the material at peak load. In the conventional indentation test, the method used to determine this critical parameter is based on purely elastic contact mechanics. The contact area is underestimated for elastic-perfectly plastic solids and the error is more significant when piling-up occurs. AFM measurements performed on the residual impression of pure metals, stainless steel often used as substrates for thin film deposition and tungsten coatings of various residual stresses, provide a good estimation of the contact area between the indenter and the material. Moreover, they highlight the main difficulties to estimate the contact area mostly in the conventional nanoindentation of viscous-plastic materials. Other effects as indentation size effects are detected. The hardness of tungsten calculated from AFM measurements agrees with the one determined in the nanoindentation test except at loads of 0.1 N, that is correlated to the formation of folds of about 150 nm high around the residual impression. Because of piling-up effects occurring at 0.1 N, the contact area determined in the nanoindentation test is underestimatedRead More
Publication Year: 2011
Publication Date: 2011-01-01
Language: en
Type: preprint
Access and Citation
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot