Probing the local creep mechanisms of SiC/SiC ceramic matrix composites with high-temperature nanoindentation

Abstract

Here, we probed the local creep response of SiC/SiC ceramic matrix composites via high-temperature indentation to examine the contributions of heterogeneous microstructure to creep. Indentations were conducted up to 800 °C on single and polycrystalline Si and SiC, reaction-bonded SiC, and the SiC/SiC composite, which indicated higher creep strain rates of polycrystalline materials yet uncovered comparably lower strain rates of the SiC/SiC composite. Indentation creep rate was observed to be highly dependent on contact stresses. An analytical creep model was presented based on a rule of mixtures approach to incorporate material heterogeneity of the SiC/SiC composite. A finite element model was applied to predict the indentation deformation zone, in which the composite constituents would jointly influence the creep response. The analytical model was then solved for temperatures up to 800 °C and exhibited good agreement with experimental measurements.