Fracture Behavior of Single-Crystal Silicon Microelements and Nanoscopic AFM Damage Evaluation

摘要

Simple bending tests of single-crystal silicon microelements fabricated by photoetching were performed. Silicon microelements deformed elastically until final catastrophic failure, showing a brittle nature. The fracture strength increased with a decrease in specimen size, and the maximum strength reached about 8 GPa. However, the Si microelements were sensitive to notch, and nanometer-deep notch caused a decrease in the fracture strength. In laboratory air, no fatigue damage was observed even though the surface was nanoscopically examined by an atomic force microscope (AFM). However, the fatigue lives in water were decreased compared with that in air. Crack formation in {111} plane was promoted by a synergistic effect of dynamic loading and water environment. An AFM was capable of imaging nanoscopic cracks, which caused failure in water.