Nanoscale AFM and TEM Observations of Elementary Dislocation Mechanisms

This thesis addresses elementary dislocation processes occurring in single-crystalline alloys based on Fe-Al, and investigates correspondences between dislocation distribution inside crystals characterized by transmission electron microscopy (TEM) and surface patterns observed using atomic force microscopy (AFM). Fe-Al alloys with different degrees of ordering were prepared and deformed in compression at ambient temperature in-situ inside the AFM device. The evolution of slip line structures was captured in the sequences of AFM images and wavy slip bands, while cross slip at the tip of the slip band and homogeneous fine slip lines were also identified. Further, the thesis develops a technique for constructing 3D representations of dislocations observed by TEM without the prohibitive difficulties of tomography, and creates 3D models of dislocation structures. Generally speaking, the thesis finds good agreement between AFM and TEM observations, confirming the value of AFM as a relevant tool for studying dislocations.