Interface Segregation in Advanced Steels Studied at the Atomic Scale

• Published in: Microstructural Design of Advanced Engineering Materials pp. 267 - 298
• Main Authors: Raabe, Dierk, Ponge, Dirk, Kirchheim, Reiner, Assadi, Hamid, Li, Yujiao, Goto, Shoji, Kostka, Aleksander, Herbig, Michael, Sandlöbes, Stefanie, Kuzmina, Margarita, Millán, Julio, Yuan, Lei, Choi, Pyuck‐Pa
• Format: Book Chapter
• Language: English
• Published: Weinheim, Germany Wiley‐VCH Verlag GmbH & Co. KGaA 14.08.2013
• Subjects: Gibbs adsorption isotherm; Gibbs free energy; grain boundary segregation; maraging; martensitic steels; nanostructured materials
• ISBN: 9783527332694; 3527332693
• DOI: 10.1002/9783527652815.ch11

Advanced metallic alloys for structural applications can be nowadays understood and hence manipulated down to the nanometer scale. This applies particularly to interfaces in high‐strength steels: Their structural and chemical state can be a decisive factor of whether the bulk material reacts brittle or ductile against external loads. In this context, segregation of solute atoms to grain boundaries plays a major role. In this chapter, we give an introduction to the current state of chemical grain boundary analysis in advanced steels using atom probe tomography. The necessity and challenge in coupling such near‐atomic chemical interface characterization via atom probe tomography with structural analysis through electron microscopy of the same material region is discussed and corresponding examples are presented. Theoretical analysis of grain boundary segregation phenomena is conducted on the basis of the Gibbs and McLean isotherm approaches and also in terms of a more recent phase field approach. Examples are given for maraging and martensitic steels.