Dislocation Theory

This course explores various theoretical models used to calculate the energy of dislocations in crystalline materials, with a focus on their deviation from real dislocation core structures. Dislocations, which are line defects in crystals, play a critical role in determining mechanical properties such as strength and ductility. While classical continuum models offer approximations of dislocation energy and behavior, they often fall short in accurately capturing the complex core structures that occur in actual materials. The course addresses these limitations by comparing idealized models with atomistic simulations and experimental observations. Special emphasis is given to dislocations in face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal close-packed (hcp) crystal structures, each of which presents unique core configurations and mobility characteristics. In addition, the course covers dislocation behavior in more complex systems such as superlattices, where the formation of anti-phase boundaries and chemical stacking faults introduces further complexity in dislocation mechanics. Through this comparative approach, students gain a comprehensive understanding of how dislocation models are developed, validated, and applied to predict material behavior. By bridging the gap between theory and real crystal behavior, the course provides a foundational framework for analyzing and understanding the dislocation mechanism in designing materials with tailored mechanical properties.