Nanoindentation of polycrystalline silicon-carbide thin films studied by acoustic emission

Abstract

Nanoindentation experiments and in situ monitoring of acoustic emission (AE) were used to investigate the evolution of deformation in polycrystalline silicon-carbide thin films. An acoustic sensor attached to the holder of the indenter tip was used to continuously record the AE signal during nanoindentation. The amplitudes of the AE wave forms were used to analyze the response of the indented films in the time domain. In addition, a hybrid time-frequency analysis of the AE events was performed in order to determine the dominant frequencies of the deformation events encountered during nanoindentation. The effects of the film thickness and microstructure and the indenter tip radius on the film deformation behavior are interpreted in terms of the AE response and associated deformation mechanisms. The findings of this study demonstrate that in situ AE monitoring provides potentially useful information about microstructure changes associated with nanoscale deformation processes, such as grain boundary cracking, in thin films subjected to normal contact loading.