Grain boundary segregation engineering in metallic alloys: A pathway to the design of interfaces

• Published in: Current opinion in solid state & materials science Vol. 18; no. 4; pp. 253 - 261
• Main Authors: Raabe, D., Herbig, M., Sandlöbes, S., Li, Y., Tytko, D., Kuzmina, M., Ponge, D., Choi, P.-P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2014
• Subjects: Alloys; Atom probe tomography; Coefficients; Cohesion; Decoration; Grain boundaries; Grain boundary; Heat treatment; Materials science; Phase transformation; Precipitates; Segregation; Segregations; Phase transformation; Segregation; Atom probe tomography; Grain boundary
• ISSN: 1359-0286
• DOI: 10.1016/j.cossms.2014.06.002

•Segregation engineering: grain boundary manipulation by solute decoration.•A concept to manipulate grain boundary structure, composition and properties. Grain boundaries influence mechanical, functional, and kinetic properties of metallic alloys. They can be manipulated via solute decoration enabling changes in energy, mobility, structure, and cohesion or even promoting local phase transformation. In the approach which we refer here to as ‘segregation engineering’ solute decoration is not regarded as an undesired phenomenon but is instead utilized to manipulate specific grain boundary structures, compositions and properties that enable useful material behavior. The underlying thermodynamics follow the adsorption isotherm. Hence, matrix-solute combinations suited for designing interfaces in metallic alloys can be identified by considering four main aspects, namely, the segregation coefficient of the decorating element; its effects on interface cohesion, energy, structure and mobility; its diffusion coefficient; and the free energies of competing bulk phases, precipitate phases or complexions. From a practical perspective, segregation engineering in alloys can be usually realized by a modest diffusion heat treatment, hence, making it available in large scale manufacturing.