Internal interfaces, stacking faults and dislocations determine many mechanical, functional, and kinetic properties of alloys. These defects can be chemically manipulated by solute decoration, confined elemental partitioning and even by low-dimensional transformation phenomena, altering their energy, mobility, structure, and cohesion. Some of these phenomena are long known: Examples are Cottrell atmospheres at dislocations, Suzuki partitioning to stacking faults and grain boundary segregation according to the adsorption isotherm.
The lecture presents and discusses three aspects in that context. First, recent atomic-scale experiments show that the interplay between defect structure and chemistry can lead to a much larger variety of compositional – structural states than commonly assumed. Second, some of these states can be described by established thermodynamic and kinetic models. Third, embracing the full complexity of these defect decoration states via alloying and thermomechanical treatments establishes an approach referred to as 'segregation engineering'. In this concept defect decoration and transformation are not regarded as undesired phenomena but instead utilized to manipulate specific interface and dislocation structures, compositions and properties for advanced microstructure design.