Abstract
Nano-indentation test on polycrystalline silicon nitride and single crystals of silicon carbide is done to examine the indentation size effect (ISE). The hardness is evaluated by using the Oliver-Pharr scheme. The experimental results are analyzed on a dislocation mechanism model based on the punching of prismatic dislocation loops to accommodate the volume of plastic penetration at the indentation. The parameters of the model are determined numerically by solving the inverse problem, using the parameters obtained from loading-unloading curve. The theoretical results show that the profile of plastic core zone do not evolve in a self-similar manner with decreasing load. The ratio of plastic work for punching dislocation with respect to total work decrease with decreasing load.
