Investigation of Atomic Structure Ahead of Crack Tip by STM and AFM

摘要

Studies of surface cracks were conducted to understnad the nanostructure and atomic structure ahead of surface crack tip with or without applied loading, using Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM). For unloaded crack tips on the (0001) surface of highly oriented pyrolytic graphite there are many small voids or vacancy clusters ahead of the crack tips, which may migrate and merge into the cracks. For loaded crack tips on the (0001) surface of mica samples, there exists a severely distorted zone ahead of the loaded crack tips, in which the arrange of atoms is in disorder, and there are many vacancies and vacancy clusters. Around the distorted zone there exists an abnormal elastic region, in which the atoms can be detected.