Basinski Szczerba Niewczas Embury Basinski Thetransformationofslipdislocationsduringtwinningofcopper aluminumalloycrystals

Face-centred cubic metals deform primarily by slip until they reach a high flow stress and dislocation density; under certain conditions, the deformation transition to twinning. This work examines the dislocation substructures in the parent and twinned portions of thin foils cut from deformed Cu-8 at. % Al alloy crystals. It confirms theoretical predictions while providing explanations for previously puzzling observations regarding dislocation transformations. The analysis indicates that twinning can enhance the strength of the material. The mechanisms by which deformation twinning occurs, particularly in pure fcc metals and certain alloys deformed at various temperatures, underscore the importance of the pre-existing dislocation substructure in this transformation. The findings reflect the complex interactions and relationships between slip and twinning processes, thus revealing the nuanced behavior of dislocation dynamics in metals under mechanical stress.