Size-dependent mechanical behavior of a-silicon carbide nanowires under in-situ transmission electron microscopy tensile tests

In-depth understanding of mechanical behavior of silicon carbide (SiC) at nanoscale was of great importance for its widespread application. However, the exploration of the relationship between mechanical properties and deformation mechanism has been impeded due to the lack of in situ measurement technology. Here we comprehensively studied the mechanical behavior of single crystal alpha-SiC nanowires (NWs) via a micro-electro-mechanical-system (MEMS) based in situ transmission electron microscopy (TEM) tensile experiments. Young's modulus, fracture strength and elastic strain limit of alpha-SiC NWs with the diameter ranging from 48 nm to 182 nm were investigated. Combining the various existing results of SiC nanostructures, general trends were found that fracture strength and elastic strain limit increased with the decreasing of diameter, while Young's modulus kept constant. Besides, all of the alpha-SiC NWs were elastically deformed until brittle fracture during tensile tests. By the aid of the in situ observations of deformation processes and fracture morphologies, the mechanism of size-dependent fracture strength and elastic strain limit of single crystal alpha-SiC NWs were discussed. The present findings provided guidance for the development and application of advanced micro-/ nano- electronic devices with the comprehensive usage of SiC NWs in the future.