A Dislocation Perspective on Strength and Toughness in Ceramics

Ceramics are widely known to be brittle. Yet in recent years, there has been a growing interest in the research domain of strengthening or toughening ceramics with dislocations, a fundamental crystal defect that has been perceived as uncommon or irrelevant in ceramics. With new methodologies being developed for mechanical deformation, fabrication, and processing, dislocations are increasingly spotted or purposely engineered in ceramics for the technological potential they may hold. This article aims to provide an overview of the historical development of this topic concerning dislocation-impacted strength and toughness, covering three major research waves over the last nine decades. This historical retrospective provides valuable insights and useful guidance for understanding the currently ongoing research endeavors in using dislocations for potentially stronger and tougher ceramics, as well as for balancing the mechanical and functional properties. A few outstanding issues concerning dislocation engineering, work hardening, dislocation fatigue, dislocation/defects interactions, and external fields affecting the strength and toughness of ceramics are discussed. Although there have not yet been mature engineering applications for dislocations in ceramics, with dislocation being a fundamental crystal defect and more readily present in ceramics, the increasing proofs-of-concept continue to add weight to its roles played in advanced ceramics engineering.